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More on the Units of Energy
Posted by Heading Out on January 19, 2007 - 10:42am
When we talk about Energy, it is often hard to get a good feel for the quantities that we are talking about. The United States uses about 100 Quads of Energy a year where a Quad is a quadrillion Btu’s. When I first saw that, I had to go away and look up how much a Quadrillion was, and could barely remember a British Thermal Unit (Btu) from when I was in school. And given that we are now thinking of using Exajoules instead (a Btu being roughly 1,000 joules), life seems to be getting a little beyond the stretches of my imagination.
Units tend to be something that was originally almost an arbitrary choice. For example, when I want to cook fish, I know that it takes 10 minutes per inch, and so I use the first joint on my forefinger to see how thick the fish is and to decide how long to cook it. (And it works out quite well). When I need to buy something to length, I can get a first sense of how much I need by spreading my palms and touching my thumbs and from one side of one hand to the other side of the other is close enough to a foot. But a Quadrillion (1,000,000,000,000,000 in the US – add 000,000,000 to the end for the British system) is a little hard to visualize. Showing the volume occupied by a quadrillion pennies doesn’t really help much. And as for the Btu, well it’s the amount of heat required to raise the temperature of 1 lb of water by 1 degree Fahrenheit. Which would be good to know if I could remember how much volume there was in a pound (Oh! Yes there are 8 fluid ounces to a cup). So how can we get a real sense of how much energy we are talking about? After all we measure natural gas in thousands of cubic feet (or meters), coal in tons (or is it tonnes); oil in barrels; while wind, solar, nuclear and hydro usually are given in either billion kilowatt hours a year or in megawatts (though sometimes acre-feet has an impact on hydro). So how do we decide if spending $138 million on a wind farm in New Zealand that will produce 88 megawatts, or one that will generate 132 megawatts in Maine is a better idea that, say, installing an LNG vaporization plant that will produce 400 million cubic feet of natural gas a day in Connecticut. Well to begin with it would help if we could reduce all the different terms to a common comparative base. And so that is what this post is about.
Since this is the Oil Drum, and we have an idea as to how big an oil barrel is (though remember that it is 42 gallons and not 55), I am going to use a barrel of oil as the basic unit for comparison, and will insert a comparison table just a little further down the post.
But you need to bear in mind that not all oil is created equal. There are sweet crudes, and sour crudes, heavy crudes and light ones, and they can all be refined to give different fractions of their volume into a variety of hydrocarbon products. (See Robert's informative post on this ). So the number that I use will be an average. But it also helps to remember how powerful this fluid is.
Consider that the average car might weigh 3,500 lb which, with a couple of folk inside could readily get the weight up to two tons. Now if the average mileage it gets is 21 mpg, and lets say it gets this while doing 63 mph, then it takes 20 minutes and 1 gallon of gas to get the car moving those 21 miles. Put another way, in a minute the car will have gone just over a mile and used 0.4 pints of gas, or, in a second it will have used almost a teaspoon of gas, and moved the car and contents some 92 ft. Pretty powerful stuff! And so, as a measure of performance, a barrel of oil will move the average car and family, about 900 miles. (Incidentally at an efficiency of around 1-2% but that will be another story).
In 1954 there were 511,000 oilwells in the United States, with an average production of 12.4 barrels a day (bd). By 2005 the number of wells had dropped to 506,000 with an average production of 10.1 bd. In Europe it is more common to find the amount of oil produced being given in tonnes, thus when a story, such as the restart of oil flows through Belarus comes along it often contains both sets of units, which may make it a little more difficult to understand. Based on a discussion we had in comments, one can multiply the tonnes by 7 to give barrels, so that the tax that Belarus was seeking to apply was some $6.50 a barrel. Alternately when Russian production is reported as 438.7 million tonnes from January to November we divide by 11 and multiply by 12, to convert it to an annual rate, then divide by 50 and get a production rate of 9.57 mbd.
In the same way as oil has a variety of assays – or contents, so also is coal not a simple product and so for this also we use an average. A ton of coal fills about a cubic yard of space (depending on how it is packed). Back in the days of hand-loading coal, a miner might expect to mine up to 20 tons a shift, depending on the conditions. (Remember the song “Load fifteen tons and what do you get?) On the other hand China produced 2.3 billion tons last year. That is the equivalent of about 24.5 million barrels of oil a day (mbd). The Chinese production is about 35% of world production , yet the industry is so inefficient that the average miner will only produce around 321 tons a year (about 1,250 barrels of oil). Very roughly a ton of coal is equivalent to around 4 barrels of oil. In 2005 there were 670 underground, and surface coal mines in the United States and they produced 369,370,807 tons from underground and 765,662,208 tons from surface mines, for a total of 1,135,033,015 tons , the equivalent of 12 mbd.
When one looks at natural gas, the difference between Europe and the United States is reflected in that one measures in cubic meters, and the other in cubic feet. So by normalizing to barrels a day of oil equivalent we can get over that confusion. For example while the Shah Deniz gas field came back into production too late to save Lord Browne’s job, it is now producing 3.4 million cubic meters of gas a day. It sounds a lot but is only the equivalent of 16,000 bd – though since that is coming from a single well it is definitely not something to be sneezed at. And going back to that LNG facility in Connecticut. If it plans to vaporize 400 mcf of natural gas a day, that is 0.146 trillion cubic feet (tcf) of natural gas a year, the equivalent of 70,000 bd.
And that brings us to the direct power producers, the wind turbines, hydro-electric power plants and nuclear facilities. And here also you find some confusion between reported production numbers that requires that you know the difference between kilowatts, megawatts and kilowatt hours. There is also an efficiency factor in the conversion of the wind/solar energy/ nuclear pellet to electric power that sometimes can, and sometimes cannot easily be changed. Consider, for example, that a single nuclear pellet in a reactor is about 0.3 inches in diameter and half-an-inch long and yet has the power of 3.5 barrels of oil. Here is not the place to get into a discussion of the varying power demands over the course of a day or year, and the changes in power prices that go with them. But it is necessary to talk just a little about the difference between power and energy.
To start at the beginning a generator (wind turbine, nuclear pellet, solar cell) puts out a certain amount of power. This instant value is generally measured in watts (a kilowatt being 1,000 watts and a megawatt being a million watts, and a gigawatt is a million kilowatts). Thus, to use the example cited, a light bulb might consume 75 watts. If it burns for an hour then it will use 75 watt-hours, or 0.075 kilowatt hours (kwh). But because demand varies, so the size of the power supply that is required must also not only vary, but be able to cope with the largest demand placed on it.
For instance, a 100 MW rated wind farm is capable of producing 100 MW during peak winds, but will produce much less than its rated amount when winds are light. As a result of these varying wind speeds, over the course of a year a wind farm may only average 30 MW of power production. Similarly, a 1,000 MW coal plant may average 750 MW of production over the course of a year because the plant will shut down for maintenance from time-to-time and the plant operates at less than its rated capability when other power plants can produce power less expensively.
The ratio of a power plant's average production to its rated capability is known as capacity factor. In the previous example, the wind farm would have a 30 percent capacity factor (30 MW average production divided by 100 MW rated capability) and the coal plant would have a 75 percent capacity factor (750 MW average divided by 1,000 MW rated capability). Load factor generally, on the other hand, is calculated by dividing the average load by the peak load over a certain period of time. If the residential load at a utility averaged 5,000 MW over the course of a year and the peak load was 10,000 MW, then the residential customers would be said to have a load factor of 50 percent (5,000 MW average divided by 10,000 MW peak).
Knowing the peak and average demand of a power system is critical to proper planning. The power system must be designed to serve the peak load, in this example 10,000 MW. But the actual load will vary. The load might be 10,000 MW at noon, but only 4,000 MW at midnight, when fewer appliances are operating. The capacity or load factor gives utility planners a sense of this variation. A 40 percent load factor would indicate large variations occur in load, while a 90 percent load factor would indicate little variation. Residential homes tend to have low load factors because people are home and using appliances only during certain hours of the day, while certain industrial customer will have very high load factors because they operate 24 hours a day, 7 days a week.
The amount of electricity consumed by a typical residential household varies dramatically by region of the country. According to 2001 Energy Information Administration (EIA) data, New England residential customers consume the least amount of electricity, averaging 653 kilowatt hours (kWh) of load in a month, while the East South Central region, which includes states such as Georgia and Alabama and Tennessee, consumes nearly double that amount at 1,193 kWh per household.
More detailed energy use for households can be found at the EIA website .
So if we have a power plant that has a maximum operating capacity, for example, of 750 MW and runs at 50% capacity, on average, then it will produce 750,000 x 365 x 24 x 0.5 = 3.3 billion kWh per year, the equivalent of 16,000 bd of oil.
There are other posts on the site, that I will gradually find and incorporate, that discuss such things as wind turbine load factors, but I think I may have given you enough to think about for now.
I will end with a couple of tables for conversions, which I adapted from those given by Stobaugh and Yergin, from their book “Energy Futures.”
And for those who, in times when power supplies are questionable, rely on a wood stove. From Wood: An Alternative Source for Home heating (pdf file).
Oh, and for those of you who wondered about the Quad, it is the equivalent of 470,000 bd of oil for a year. And, to make a final point, when the Government are reporting that the ethanol target for 2012 is 7.5 billion gallons , remember that you divide first by 42, which gives 178 million barrels a year, and then you divide by 365 to get 489,000 bd. And so you may initially think that the target is a Quad, but you still have to remember that ethanol has only about 60% of the energy of gasoline, and so the target will be around the equivalent of 300,000 bd of oil. Doesn't quite sound as much, does it ?
The Oil and Gas Journal give the following numbers for US Energy Demand in 2006
Oil 40.6 Quad
Gas 22.6 Quad
Coal 22.8 Quad
Nuclear 8.3 Quad
Hydro etc 6.5 Quad
Contact
- Content: editors at theoildrum dot com
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I'm surprised by the differential between a ton of coal and a ton of oil. Obviously, what makes each weigh a ton is predominantly carbon atoms, thus the differential must be due to the higher heat to mass ratio of burning hydrogen molecules/atoms. This is a greater ratio than I would have at first thought.
Perhaps we could get a sense of this from a comparison of the output heat to mass ratio for NG and see if it correlates back to almost doubling the output per ton.
I can see why the maritime world was so glad to go diesel over coal. No shoveling and you went twice as far, which is a big factor out at sea. You're stuck at hull speed anyway. Oil, nothing like it.
Excellent essay. I did note that your coal miner loaded 15 tons rather than the historic 16 tons of the song. Perhaps we need a discussion of long tons and short tons. Or, maybe, it's coal inflation working its way through the system. Units are a pain.
Grin, I think I implied that I actually did 20, but then that would be bragging.
Arghh. I assume that the conversions are only for heating values, and not for thermodynamic work.
An important distinction is between the value of heat and electricity.
It takes about 3 btu's of heat to get the equivalent of 1 btu of electricity (less for very efficient central plants, more for inefficient ones), and yet we value the electricity more than the heat. So, btu's and quads are not such a great standard metric for measuring energy.
39 of the US's 100 quads generates 13 quads of electricity.
If you compare renewables, that put out electricity and don't have heat inputs, to thermal plant heat inputs, it will undercount renewables by a factor of 3.
If you compare the heat value of gasoline to the energy content of a battery, you'll undercount the value of the battery by perhaps 6 to 1, as the average gasoline engine is about 15% efficient, and an electric battery-motor system about 80%.
This is a very important point! And it is one that is often overlooked when comparing alternative energy systems that generate electricity directly, such as photovoltaics and wind turbines, with electricity generation via fossil fuel-fired heat engines running generators.
When a wind turbine puts out the equivalent of 1 million BTUs of energy in the form of electricity, it is not displacing 1 million BTUs of fossil fuel, but more like 3 million BTUs of fossil fuel (based on an overall powerplant efficiency of something like 30 - 35%). This, of course is a very crude comparison, and doesn't take into consideration the energy input of construction, energy payback period, etc., but I think it illustrates the point.
It is also well to keep this difference in mind when considering electric cars. The energy content of a gallon of gasoline is roughly 36 kilowatt-hours. But if you have a battery-motor system with an overall efficiency of 80% , you will be able to drive that car the same distance as you would on 4 or 5 gallons of gasoline, all other things being equal (such as vehicle weigh, rolling friction, aerodynamics, etc).
Hmm, you call yourself "joule" and use BTUs and kW-hrs in a post on confusing energy units. How perfect is that?!?
Ho, Ho!
It's just a matter of convention that's all. In the US at least, the energy content of fuels is usually given in BTUs (per unit weight or volume), whereas the charge-holding capacity of a large battery is usually given in kilowatt-hours.
But if one is actually doing energy calculations, then of course it should all be in the same units, such as joules.
No, stick to your guns. If you measure heat & electricity with the same units you create the confusion we've been talking about.
I'd always assumed figure of about 20 to 25% for gasoline and about 30% for a good diesel, and steam only manages 20%. When considering electric motors at 80%, we must also factor in the percentage loss in the battery for charge and discharge. There's an exponential [damn those exponentials!] increase in loss to heat with increasing charge rates which plays hob with regenerative braking and downhills. No free lunch during storage. Some types of battery internally discharge to an extent over time also.
Bicycle is still looking good in comparison. Sailboats too. How about fewer humans and more horses?
Steam power plant can range 30-40% efficient, depending of the pressure. Motors larger than 1 hp have efficiencies > 90%.
"Bicycle is still looking good in comparison."
How is a bicycle looking good? Human muscle has an efficiency of 15% or so, unless you are a trained athlete with the right genetics, in which case you get a few percent more (this is not taking the 100W your body needs to repair itself, to run the heart and brain etc. into account!). A 150lbs man at the height of his physical potential can probably output 100-150W continuously for eight hours and five days a week without lasting physical harm. And that would be a very hard day at work, indeed! After a couple of years on that job you might as well wrestle Conan The Barbarian...
In comparison, a modern 1kW AC motor weighs probably some 20lbs, runs at 90% efficiency 24/7 until the ball bearings bust and does the work of 30 sweaty people (three shifts of 6 people, 5 days a week plus vacation and holidays). It can be powered off less than 100m^2 of solar cells (at 20W/m^2 of average capacity and including all electrical losses for battery or hydroelectric storage etc.). With solar electricity costing some 25cents/kWh for a current small industrial generation scenario, our little machine will run on $6 worth of electricity a day (and don't get me started about how much it will cost on wind energy...).
The equivalent 30 people will require 90 acres to support (US farm area is 900 million acres for 300 million people, i.e. we use 3 acres per capita. This includes the cost of raising children, feeding the elderly, launching space shuttles, etc. but is not representative for the caloric intake of hard physical workers! Since an acre is 4046m^2, the ratio of land use is by a factor of 3641:1 in favor of that electrical little machine. If you don't believe me, call me once you have found a way to support 30 laborers on $6 a day.
"How about fewer humans and more horses?"
Horses are probably similar to humans within a factor of a few. I don't really care to learn much about horse physiology until the turbo horse with 800MWh annual energy output/acre grassland has been genetically engineered. Why? Because 15% efficient solar cells produce 607kWe/acre peak for some 4hours per day on average, i.e. we get 2427kWh per day. That's 886,000kWh/acre annually. So the horse would have to come in at close to 800MWh of mechanical output. Such a horse would work at 80kW continuosly, which is roughly 100hp...
Wow... some horse that would be. It probably goes 150mph on the highway, too!
Outsource to prison labor in rural China....
Since I need the mechanical work here, I'd have to build an 8000 mile long curved crank shaft, first.
Dang it, Infinate, I'm about ready to pay the daily fee to get into a gym and spend some time on a stationary bike to see what kind of watts output I can do for an hour, and I'm not in shape! Not a very big person either, but I'm sure I can do 200W for an hour, while reading the TV Guide or watching a soap.
150W for 8 hours for the average guy should be a no-legger lol.
And a skilled bike rider won't be able to take on Conan the Barbarian, but they'll be able to out-bike him!
OK... I am a little, bald and fat man (;-)) who works out on a rowing machine, when he works out. Without any training I manage 80-90W for an hour on day one. With a couple of weeks of training I manage 120W and I bet I could get up to 150W IF I really wanted to (but I don't wanna... I am lazy :-)). The longest I ever tried was 2 hours (and close to 1200kCal) and I noticed that it gets easier the longer you go. But that's because my rowing technique sucks and I waste a lot of energy on the wrong movements. But even so I don't think I could last for much longer than three to four hours without very serious training (and certainly not without glucose intake - which I never tried).
I know much better built guys who work out daily for an hour or two and they can do 250W or so (you better be able to do that and 500W peak or so until you black out if you want to be on the rowing team). Top athletes like those riding in the Tour de France can do 400W for hours as far as I know.
100-150W for eight hours will be a lot. Don't forget that you have to eat some 600kCal/hour to make up for the glucose/glycogen you burn! So in an eight hour work day that's 4800kCal on top of your 2500kCal regular diet. Can your guts even absorb that much???
All numbers are rough estimates based on my Concept II indoor rower display. The machine measures true mechanical power output based on the physics of a flywheel and is so precise that it is generally accepted for indoor competitions.
OK I just did a 3k, and the wattage was 101. But, a rower is different from a bike, a bike is the most effecient means known for a human to move across the landscape, rowing has never been called that. Remember there's a drag factor on these machines, to simulate the drag (loss) of the water.
We both need to get on stationary bikes and see how we do, or better yet, I bet there are some cyclists out there, a lot of them, from tourers on up, plotting how they do, wattage-wise, for X amount of distance. Remember not all serious bikies are racers, some are tourerers or "randonneurs" but they still get into tracking things like wattage, some of them.
100W for a nice cardiovascular workout sounds about right. The trouble is not to do it for 3k but for 300k. I don't think my bottom could handle that. Ouch...
Rowers are very efficient because they can make use of legs, arms and upper body in every motion. The rower's body is typically well proportioned and, IMHO, a lot more attractive than the biker's (all legs, no arms...). The competition is not fair, though, because rowing is typically a sprint discipline while professional cycling is about going the distance and I am sure the muscle physiology is very different in athletes of both disciplines.
It is interesting to note that a rower can black himself out by removing so much oxygen from the blood that the brain sets out. From what I have heard about professional rowing, the goal is to nearly black out on the last pull. One pull too early and the boat will be a bloody mess because tangled oars at that speed are enormously dangerous. I had a few "accidents" with other beginners on the water at low speeds and black thumbs is the least that can happen. The worst thing is that everyone lands in the water, but I guess if that happens to a professional, he or she probably doesn't have to show up for a few training cycles...
I don't doubt that humans can do amazing things physiologically, but it is absolutely clear that machines are by far more capable. I, for one, wouldn't want to compete seriously against my notebook battery and a brushless RC flight motor weighing two ounces or three. I might even win, but only barely. And by weight... let's not even go there!
Infinate - you just enumerated why I decided to bust over $800 to get my own ConceptII.
There's one up at the local gym, and for $300 a year, I could use their rather germy Model C, or for a depreciation of about $200 a year, have a nice new Model D here to trip over sometimes, like I did this morning, and other than that, hop on and row. Much cheaper than living on the water which is what it would take for me to get out on a scull daily.
For a 5'4" 45-year old female who's a good 30 lbs over "fighting weight", not bad. When I was a a decade younger and much more fit, I seem to remember putting out more wattage on a rower, it was probably a model B or early model C, I hung with some rowers, mostly or all heavyweights, who were told to row for X minutes, doing at least Y watts. They were impressed, I thougth it was a workout, hehe.
Rowing is a much more balanced exercise. For weight loss, Concept II recommend doing a 5K a day but of course that's just a very general rule - l lot of serious erg'ers do more, and they mix it up, power 10's and 20's and intervals etc.
I decided this is cheaper than running, even, since running shoes cost a bit. I still will probably go out and do runs too. Just to mix it up.
But a rower, pushups, situps, maybe some burpees and boxing type stuff, and you've got a pretty thorough workout. I'm falling into using pushups etc to warm up for the rower.
Yes, on the real boat - all kinds of "neat" things can happen! You get tons of blisters at first, you don't have to feather the oars on a rowing machine! And your hands collide, at best it's some blood and lost skin to your own nails. Then there's catching a crab, or does the crab catch you? You can end up right in the water if you do it "right" lol. Tons more skill needed to go fast in the boat, you can get strong as a horse on the erg and if you go out and learn it on the water, it's all pussyfooting around, you'll never use those muscles you built up. And that's if you grew up knowing which end of an oar is which, I'm a "natural" but I'm here to tell you, (bush voice) it's hard.
Yeah I'd rather see the Peak Oil Man in that movie warming up with some burpees then using a Concept II to power his little TV, hehe.
It's a fun machine... not as fun as being on real water, but much easier, indeed. I hate gyms. I rather work out on one simple, high quality machine at home than to be on some high tech robot equipment among other sweaty people. Either that or just ride my bike for fun (not for sweat).
I find that for weightloss a slow, steady rythm is much better. Of course, it gets boring rather fast, but if I am at 70-80% of my limit, I can go for a long time without hurting and I am more interested in doing 400-600kCal regularly than 1200kCal once and then lose all interest for a long time.
It seems that the general idea with cardiovascular workout is to push the heart rate higher for fitness but lower for simple calorie burning. The additional effect is that if I go faster than I can produce glucose from glycogen, I develop an enormous hunger afterwards, which usually completely swamps the energy expense and is totally counterproductive to the effort. But if I go nice and slow, I don't get hungry much at all. I did a few experiments on myself and found this to be a pretty good rule: keep the heartrate at 120-130 and don't try to be a hero... sweating starts after ten, fifteen minutes and if I keep myself hydrated, it is a very effective exercize to compensate for being a couch potato the rest of the day. I monitor my heart rate and not the power or cal/h or time display! And if I am too fast, I slow down and that is easier on the hands, anyway.
So that's what I am using my rower for... the professionals would laugh at my whimpy efforts, but then, I don't have to prove anything to anyone. I want to feel good, compensate for loss of back muscles due to sitting all day and that's pretty much it. I can live with the fact that I will never win the olympics... because none of you except for one, will either. :-)
I agree, most rowers push themselves to the limit on the machine. It is easier because it does not require nearly as much technique as being in a real boat. The downside is that it is easy to forget all about technique and row like a pig. I wouldn't want to be in a real boat without a refresher class after all these years. I would probably just capsize or crush my thumbs... which I did often enough.
Actually, I thought about making electricity with the rowing machine once. But then I calculated that it would take me ten hours of hard work for 15 cents of return... just didn't seem worth the effort.
:-)
Well, Floyd Landis did 230W average across the entirety of his (possibly hormone-fortified) Tour de France performance (a few hours per day), so 150W for 8 hours is not easy at all. Look in my old oildrum article for more info.
Ha! Now that is a great article bringing it to the point! And it also mentions PH (peak helium). Thanks for pointing it out, because I hadn't seen it, yet. Love it, though. :-)
I'm in pretty good shape- ran a 3 and 1/2 hour marathon not too long ago. I can do 150W continuously on an exercise bike with minimal effort. I could get 200W steady for maybe an hour. That's enough to get me sweating and slightly winded, but I could still hold a conversation at that pace. I could do bursts for several minutes at 250W, but could not sustain this for long. I doubt that I create as much electricity as is used up by the 27" TV screen I watch at the gym while I use the bike.
I did once see a story about an engineer who was worried about his kids' health when they sat around watching tv. He hooked the TV up to the exercise bike and allowed his kids to watch as much tv as they pleased, only one of them had to be on the bike to keep the tv on. They developed a system of taking turns, and they took breaks at the commercials of course. Can't remember how big the screen was, but had to be smaller.
On a related note, older exercise bikes and other CV equipment used to always run on its users energy output. Newer ones plug in to an outlet. I have no idea why.
i have often wondered how much more efficient running is than walking . a really fit runner has a much more fluid motion than a plodder. one way to tell how efficient one is running is to listen, a real good runner moves along silently while a plodder is clop clop cloping along.
I am not in that category, i.e. the runner that moves along silently, but I've been in enough long distance races to see some of the second tier African runners. When I see them in person it feels like some sort of optical illusion. The speed of the runner is entirely out of proportion to the visible effort. As much as I love it, I have to tell you it is less effecient per distance travelled than walking. One definitely burns more calories per distance running.
Here's a nice table:
http://www.nutristrategy.com/activitylist3.htm
Yes, walking is more effecient. Racewalkers put in decent Marathon times, hehe.
Read up on how Armstrong's coach looked at how the winning African distance runners ran, as the book put it, they'd not so much run as "scoot", they weren't using long strides. This is why Lance and coach decided to go with higher RPMs, they decided human lengs, his at least, may work better moving faster with less power per stroke, it may deliver more power overall and they were right. Note that Boonen, a lower RPM masher, has not been able to win a single Tour.
They also looked at Lance's power to weight ratio which is a big factor. Get the power up, keep the weight down, and there you are. Lance was like a gasoline engine competing against stanley steamers.
Back when I was a biker, a serious biker in the late 80s, and yes I wish I'd gone into that sport for at least a bit, I was a pair of legs that looked like a Marvel Comics character's, with the basic biker skinny upper body. I seem to remember being able to cruise at 150W on a stationary bike, 200W pushing it, and get close to 250W in a sprint. Sprinting was my strong suit. But I was a pair of legs, a pair of lungs, ate all I felt like, bodyfat very low, did a lot of utility "traffic" riding which meant lots of sprints etc., so my power to weight ratio and training was decent.
In parts of the world where people are using their bodies to get work done, there are some amazing feats of strength done as routine work though, some of those messengers and pedicabbers etc are doing amazing things.
Note that Boonen, a lower RPM masher, has not been able to win a single Tour.
Eh. Boonen is a sprinter, he wouldn't attempt to win the Tour.
It would be better to compare Lance to Ullrich, who was his rival all those years.
On the subject of bicycling RPM, as far as I remember, research has shown that Lance's RPM expends more energy than a slower RPM would. This has puzzled researchers since the example of Lance should suggest it was opposite, it may be that Lance is a special case.
In general I would expect that the RPM that is least degrading to your muscles would win the Tour.
i suppose your table is correct. however i am surprised by it. i wonder if the cal/hr values for running and walking (on a relative basis) are accurate for an elite runner.
I guess we don't really need people, since motors are so much more efficient. Trouble is, you can't get motors to buy stuff-- they aren't much good for any economy based on consumption.
Which just brings up the point -- if energy efficiency were the goal of our economic system, there wouldn't be any peak oil crisis. But it's not, the point of our economy is converting BTU's to dollars -- quite a different matter. So we have a manufactured crisis, but contemporary politics doesn't permit a rational response..
I agree that we have a manufactured crisis. But that is actually a good thing because it means that we have at least a good chance to "unmanufacture" it.
Typically, when nature is the source of a crisis, there is nothing much one can do about it but to ride it out and count who's left at the end of it. Despite what you hear about these things, we wouldn't be able to deflect even a medium size asteroid with today's technology. A galactic Gamma Ray Burst pointing at us would fry us without any warning, heck, even something as small as a supervolcano will put the S and G in "Sodom and Gomorrah". Good thing is: these things are rare! Your chances of being hit by a terrorist attack of marrying after age 40 are still larger than the combined risk of super-catastrophies.
PO, on the other hand, is a problem we have seen coming for 50 years. The writing is on the wall! I am told they had to re-paint it three times because it was withering off already. I do not count that among "life-threatening events your parents did not tell you about".
I do not agree on economics being reduced to "turning BTUs into dollars". Most BTUs turn into useless heat. Even the ones that heat your home are mostly wasted. You are heating a 1000 square feet or more but typically don't feel the temperature of more than the few dozen right around you. All the other energy radiates into the universe without doing you much good. That radiation can be greatly reduced by putting insulation in. A bit of aluminum foil and glass/stone wool and the problem becomes half an order of magnitude smaller. But the cost of the insulation material and the labor to install it turns into GDP just as much as the price of the BTUs you are no longer wasting would. And BTUs that are not just heating the sky can as well run a machine for you which creates even more GDP...
It all depends how you look at it.
"I'd always assumed figure of about 20 to 25% for gasoline "
That's for an high efficiency setup. The 15% average is the average for the US light vehicle fleet, which only gets about 22 MPG.
"When considering electric motors at 80%, we must also factor in the percentage loss in the battery for charge and discharge. "
The 80% includes the battery loss: li-ion's can get 95% efficiency on each side, for a net of roughly 90%. Motors are 90-97% efficient.
NIMH batteries are about 70% round trip efficient IIRC. Li-ion, especially the new generation li-ion GM plans to use, is much better.
So where are the new batteries? That's a sincere question... I would love to have some of them!
The Li polymer batteries in my laptops go dead after a few hundred charge cycles and that is not only not impressive, it simply costs a lot. Practical EVs will need thousands if not tens of thousands of cycles. NiMH like the ones used in the Prius wear out little when they are being treated sensibly, but no commercial Li battery I have seen comes anywhere close to what's needed. I wouldn't even mind backing off the runtime of my notebook as long as I don't have to buy a $200 battery pack every year and a half.
Indeed, it may be worth keeping the Prius just to find out how gracefully they age - all info we have now says, Very gracefully. There are Prii out there with 200k on the clock and counting. I've talked to people who have put large mileages on Prii, mainly the older model, the newer model's even better.
The Prius batteries are "dipped into" very shallowly, and in fact if the car runs out of gas or the gas engine malfunctions and it's running on batteries only, the user is cautioned to use the battery power only to get to a safe location, not to run them down much.
Paying a couple thou for new batteries every decade or 8 years does not bother me - it's the price of running a car. However, there is still the matter of the toxic substances in the batteries - at least the pack is big, it's not going to end up in the landfill like all those cell fone, ipod, etc batteries you all toss in the garbidge........
I keep hearing horror stories about the Prius battery going dead and Toyota not replacing it on warranty, but I only hear them from people who do not own a Prius. Toyota says they give 100,000 miles or eight years on the battery. What's the story? Does anyone outside of Toyota keep reliable statistics?
It will be interesting to see how the 2009 or 2010 model will perform. I am looking forward to that. It might just be our next car.
Battery recyling is a real problem. I would be mostly worried about lead-acid batteries that leave the official recycling cycle. I think most other types are safe now that mercury has been eliminated from most designs.
And some batteries are meant to explode after their first use, anyway (this is just for fun, the price per kWh "will kill you"):
http://depts.washington.edu/matseed/batteries/MSE/torpedo.html
http://www.naval-technology.com/contractors/electrical/saft/
If you ever get to "see" one of these coming at you, recycling is the least of your worries.
"Does anyone outside of Toyota keep reliable statistics?"
Consumer Reports does a reader survey. So far the Prius is very reliable, including the batteries.
Yep I keep hearing bad things about Prii too, but never from Prius owners. And there are tons of Prius owners out here in Cali, so far the only real complaint I've heard about is something called the "start hole cover" which is a part that covers the starter shaft or something.... unlike most Toyota parts, it's possible to install it more than one way, and if it's the wrong way it looks OK but threatens a wiring harness. Also, the pump that pumps the hot radiator fluid in and out of the little Thermos bottle it's kept in, gets noisy at times, esp. in cold weather. I'm going to talk about this to the local shop next service, which is coming up. See what they say.
"So where are the new batteries? "
They're in use in Dewalt powertools (A123systems), and in the Segway (Saft). These are the batteries GM is choosing between: both companies have contracts with GM's subcontractors to develop battery packs and control electronics, which is expected to take about 18 months. Time to market for the Volt looks to be about 3 years, which is not bad for what it is.
Lots of hobbyists are using the Dewalt battery packs for other things, like electric motorcycles & bikes, RF planes, etc.
Li-ion batteries in laptops could last many more cycles if they had any kind of heat, depth of discharge, or depth of charge management. Think how hot your laptop can get: this is death for batteries. Vehicle designers can afford to do this right. The Tesla designers say that the design of the battery pack and controls were by far the biggest design project.
Batteries don't die, they're murdered.
The point about laptop batteries running very hot is absolutely valid. My IBM does have software which allows me to stop charging at 80% (or any other point I like) and I rarely run the battery down to less than 40% during its first year. But as soon as the capacity starts to go down, my typical pattern approaches the 0%/100% scenario ever more closely, leading to exponential degradation until the runtime is less than an hour, at which point I need a new battery.
You are right... I am beginning to wonder how long the same battery would live in a temperature controlled environment.
Having said that... cars in summer are getting extremely hot. Are they planning on actively cooling the batteries?
I will check out the A123Systems and Saft websites. Thanks for the company names.
Tesla's battery pack will have active cooling. They're using conventional li-ion, and new gen has much better cycle life, but I wouldn't be surprised if GM used active cooling too, just to be safe.
Also remember the flip side of this. Often one unit of electricity can get 3-5 units of heat (through a heat pump), depending on climate and outside temperature. For temperate parts of the country is it generally true that it takes less natural gas to make the electricity to run your heat pump than it does to actually heat your home. Work is generated by taking high temperature things and cooling them down (super simplified....), so by taking a 2,000 degree flame and mixing it with air to make a 70 degree house, you're wasting most of the ability of that fuel to do work. Use a turbine to do the mixing and you can capture that work, and use it for the termodynamically easier task of moving heat from 40 degree air (outside) to 70 degree air (inside).
Anyway, measure in joules and either consider heat or work, but not both. If you want to compare all power sources then you probably should do it by heat (even with nuclear, hydro, etc...) using some reasonable conversion ratio to back out the electricity.
if you take a 2000 degree flame and the exhaust exits the house relatively cool (and i dont have an actual temperature, but this is how the newer high efficiency furnaces operate) dont we obtain 90 % efficiency as the name plate states ?
True, but not terribly relevant. Adding 1000 joules of heat to a room that's 70 degrees (when you have 50 degree air readily available outside) takes far less than 1000 joules of energy. More like 300 or so, not going to do the math right now. So, what's it going to be, convert your 1000 joules of gas into 500 joules of electricity, heat the room by 1000 joules with a heat pump and have 200 joules of electricity left over, or just burn it for heat and get 900 joules net?
Thanks HO, this is one of the confusions that makes it difficult to see the big picture.
I noticed that the links for the following are broken:
"3,500 lb" (auto weight), "2.3 billion tons" & "35% of world production" (Chinese coal production) and "1,135,033,015 tons" (US coal production).
Notice that very last "table". Oil is 40.3% of the total energy used in the US per year. It's almost as big as gas and coal use combined. I don't know if peak oil will be peak energy, but it's hard to imagine ramping up the alternatives fast enough to offset a reduction in that 40%. If Westexas is right about import reductions, and it's hard to believe that everyone else will bow down to the US and send their declining oil our way, then we're going to be in a world of hurt.
Finally, if anyone's thinking of planting some trees this year, black locust might be a great choice. They're hardy trees, grow fast, fix nitrogen, make a nice dappled shade, and as the wood chart shows, they make great firewood. Just don't plant them too close to your house, because they can be brittle, and don't think they make a good climbing tree, because they produce clusters of 2" long thorns. The Virginia Department of Forestry is a great source, but they only sell black locust in bundles of 50 seedlings or greater.
"it's hard to imagine ramping up the alternatives fast enough to offset a reduction in that 40%. "
Because electricity is so much more efficient than heat engine transportation, you only need maybe 1/6 as much electricity to replace oil.
To replace all light vehicles with EV's would require an increase in electrical generation of less than 20% - which could be easily done with wind.
The real question is converting to EV's quickly enough. GM's Volt, as well as a lot of other plug-in hybrids, is likely to be here in about 3 years. Maybe 5 years after that to ramp up to replace most of new vehicle sales, and 5 years after that to replace the 40% of vehicles which drive 60% of the miles.
Remember the EV1? If I compare that to the history of the Prius which is selling since 1997, it is pretty clear that GM likes to bite off more than it can chew. And I am not even a conspiracy theorist who thinks they killed it for reasons of company politics. I think they really couldn't deliver with the 1990s battery technology they had. Selling a car for $40k that will burn up half a dozen sets of batteries in it life worth over a 100k is hardly a business model.
So the question is, do you really trust GM to deliver now? In environmental terms the company is like a little dog: all bark, no bite. In other words: they like to piss on Toyota's leg in press conferences but then fail to deliver anything but the next bigger SUV and semi-truck.
But in reality it is not a brand related problem, at all. Here is where we really are in terms of fuel efficiency standards:
http://images.wri.org/chart_jl_enviro2006_06_530.gif
This is all politics, not technology.
Actually, from all I've read I believe GM really gets how important this is.
They know that their image has been badly hurt by the EV-1 debacle, and their CEO has publicly acknowledged peak oil, and the need to electrify vehicles.
They're using the platform they developed for hydrogen vehicles and using it for a series hybrid, where the battery replaces the fuel cell. They say this is a flex platform which will still be used for hydrogen, but I think that part is mostly PR and a bit of covering all bases just in case.
If they can pull this one off... hats up. I don't know who got them on that fuel cell/hydrogen band wagon? Was it the political lobbying department? It never sounded much like a near term technological goal that the R&D department should have picked.
A true series hybrid would be great, but will we see rather a series hybrid SUV marketed as "So much torque it can climb vertical walls!"?
OK... I get it. They made mistakes in the past, maybe the CEO can change that. I will give them the benefit of the doubt and try not to laugh until they mess it up for real. And if they actually succeed, I will stop snickering.
"I don't know if peak oil will be peak energy, but it's hard to imagine ramping up the alternatives fast enough to offset a reduction in that 40%."
You are right, renewables will not replace oil as we use it today. But they don't have to because most of the oil we use is wasted. We can say that over 50% is wasted if we look at current European demand and 70% is wasted when compared to a realistic demand some 20 years down the road. So we really only have to replace roughly one third of our current demand with renewables. That is still a lot but it is not impossible.
The black locust tree seems interesting. How long does it take for it to grow to useful size? What's the prefered climate?
The black locust tree seems interesting.
Why? The leaves it produces have a toxin that kills off other plants and keeps the leaves from breaking down. Earthworm beds don't do well with locus leaves.
They do well in 'stressed' envirnments like cities because of their toxins.
Oops... they are advertized as the ideal fire wood. Not that I need that, but having a fast acting carbon sequester would be nice. But it looks like there is no free lunch here, either. Plantations of black locust sound like a biodiversity free zone...
Oops indeed, how 'bout various nut trees? Acorns? In arid or soon to be arid areas, acacias. Think beans grow on tress? They do, on acacias. Carob's a good idea, part of the acacia family I think.
Think in terms of what will survive well if it gets warmer, and produces a general good for animals and people. Yeah that means bats and bugs and so on too.
The kinds of trees in a modern subdivision are a disaster - generally male-only to prevent messy fruit, often varieties that don't produce a thing for man, beast, or bug. Those banyans planted all over Huntington Beach as an example - sure they're hardy and are green year round, but they only thing they ever do for anyone is provide homes for little bugs I call "squaredancing skunks", open one of those folded leaves and you'll see 'em, look kind of like tiny skunks, and if you watch 'em esp. breathe on 'em, they'll start to do a little dance. And they drop out of the trees and bite ppl, a little nip but annoying.
Imagine instead an oak tree. My friend in HB watching his cats play with the acorns instead of complaining about the bugs. Squirrels making the town their home. My friends or at least the local hippies getting interested in acorn bread recipes. The occasional pruning yeilding useful wood.
When oh when will be grow beyond being Homo sapiens and progress on to Homo horticulturus?
I admit that I am totally ignorant about plants and how they form eco-systems with insects, birds and mammals. I certainly wish that our biologists were given more means to conserve what nature we have left and to rebuild some of what has been destroyed.
I am certain, however, that plants will play an enormous role in combating global warming. On a visit to Singapore last year I observed something really interesting about a ground covering leafy green plant. It was used instead of grass in the bird park and was exposed to the full sun, yet, when I put mu hand on the regular, dark green leaves, they felt cool to the touch! A nearby white stone surface was so hot that I could barely keep my hands on it. First I though the patch I tried might have been in the shade, so I tried the "experiment" across a wide area and it was the same everywhere. The plant appearantly managed, probably through a combination of IR reflection and evaporation, to stay remarkably cool. If similar results could be achieved on global scale by planting species which act as their own climate regulators, we would be in much better shape.
Solar energy has two components: the tiny amount of it that we could use to power our infrastructure and the vast amount that dominates our environment. We absolutely need to learn to use both. And the latter, I am sure will require planting vast areas with the right mix of vegetation. Somehow that just seems so much more attractive than 10 million square miles of aluminized plastic foil...
I believe it is the Black Walnut that has these characteristics. I've used plenty of black locust in my life and never noticed these characteristics. It grows like a weed in logged over patches in the Southern Appalachian Mts. Most mountain folks call it 'yaller' locust because the wood is yellow. In fact there is some controversy as to whether 'Yellow' locust is actually a different variety.
I wonder where the wood heat value chart comes from. It varies somewhat from the one I'm familiar with like here
I like Douglas Fir which on another chart shows up as ~20 M btu/cord but if you figure it by weight instead of volume, it outperforms hickory. The upshot is that it burns extremely cleanly, leaving hardly any ash. And, its a breeze to split, and its plentiful where I live.
Yup, I have a graceful black walnut that's very generous with its leaves in the fall. I mulch them coarsely and put them on my vegetable plot over the winter. The mulch is pretty effective at suppressing weed growth but the nasty chemical (it's called juglone) is largely gone by spring. I rototill the mulch in and plant with no germination problems. The mulch is a great soil builder.
The wood of choice for burning in my area is arbutus. Very dense - a fresh arbutus log in water will sink.
Screwbean mesquite - guess it has twisty pods, if they're a useable food for man or beast, they may be a good one, gunstock makers LOVE that wood.
Sorry, they should now be fixed.
HO
I remember a joke from my graduate school days. An instructor comes into class and poses the question "Which weighs the least - a pound of lead, a pound of gold or a pound of feathers".
Those students on the lower end of the grading curve will immediately answer "the pound of feathers", which of course is wrong.
Those students on the upper end of the grading curve would answer that they all weigh the same - a pound is a pound. Seems pretty obvious.
Of course the answer is that it is a trick question. Gold is traditionally measured in troy ounces and troy pounds, and a troy pound is less than an avoirdupois pound. Thus the pound of gold weighs the least.
Also, a troy pound = 12 troy ounces, but a troy ounce is approx 30 gm and heavier than the avoirdupois oz. at approx 28 gm
All illustrations of systems of measurement that should probably be obsolete, but seem to never die. I still have some Whitworth wrenches lying around from times forgotten.
You must have owned a British car at some time. Lucas electronics! Ugh!!! I had a matchbook that had printed on the cover: "Joseph Lucas, Prince of Darkness, If your lights don't work, don't try these because they don't work either".
According to the Lawrence Livermore National Laboratory (http://eed.llnl.gov/flow/02flow.php) the U.S. annually consumes 93.4 exajoules of primary energy [EIA figures from 2002, excluding petroleum used for exports and nonfuel uses (plastics etc.)]. According to the same diagram, 38% of this primary energy is useful, the rest being lost in transmission and waste heat.
I divided this energy by 300 million Americans, and found your individual share to be:
Primary energy: 320 gigajoules per year, or 876 megajoules per day, or in electrical terms, 10.14 kilowatts continuous.
Useful energy: 121 gigajoules per year, 333 megajoules per day, or 3.85 kilowatts, or 5.16 horsepower.
To picture what this modest-sounding power level could do, consider a 5 hp electric motor driving an elevator. In 24 hours, it could lift a 180 lb. man to a height of 277 miles. You'd pass the international space station, at 217 miles, in your 19th hour.
"According to the same diagram, 38% of this primary energy is useful, the rest being lost in transmission and waste heat."
The DOE calculation assumes the current generation infrastructure (which involves a lot of inefficient thermodynamic cycles and generators which are a few percent less efficient than modern machines) and the ways we make use of that energy use. But since these are inefficient by large margins, the DOE figures do not indicate that energy is put to use effectively. It only means not all of it gets converted into heat immediatelly.
Let me give you some examples: a person can be transported from A to B in an SUV just as well as in a hybrid bus and you won't notice the difference in terms of the result. In terms of energy input, however, we are talking about a factor of 10-20, which means that we can save considerable factors over the current solution for transportation and get by with much less. You don't even have to go from SUV to bus in one step. Just have two people share a ride and you are getting a factor of two, already!
If you want another example: my computer at work consumes around 100W of power continuously. I use on average something like 5% of the CPU cycles and memory bandwith while I am at work and none while I am not there (yet the machine needs to be running all the time for our backup). If I replaced this desktop with a notebook which can wake up on internet traffic, I would cut down on power consumption by about half while at work and over 90% while off work. The result would be savings of roughly 70W on average. If you add it up, that's 1.68kWh/day and some 600kWh/year (which is almost two month's worth of my family's consumption at home!). At 15 cents per kWh, my employer wastes around $90/year in energy per PC. Multiply that with the number of PCs we have (hundreds) and suddenly we are talking real money and energy here!
And if you look around, you can identify any number is examples yourself.
My suggestion: GET AN APPLE LAPTOP. They use less energy, the keyboards don't get all "creaky" and stuff and when the keys look like little mirrors from wear and the letters are worn off and you feel like installing a new KB, it costs the same $60 a decent PC keyboard will cost. After 3 years you can sell it for a good part of what it will cost to get a new one. WiFi built in, no dangles and dongles. Excellent antennas in the iBooks. Excellent batt. life. Run UNIX. And, if your home connection craps out, you can grab it and run. I had my DSL slow way down recently, not sure why, pissed me off - grabbed it and took off for a coffee shop downtown, got my biz done, actually using the open AP across the street.
In a Katrina type situation, read that as big quake, assuming I'm not squashed hehe, I could load a backpack with this, personal papers, minimal radio stuff, few tools, some food, etc and git.
Lappys are great. You won't get carpal tunnel from a mouse either.
I wish... the kind of software I am running for my work only works on PCs and will never be written for OS X. And most of it will probably not make it to Linux anytime soon, either. :-(
I am experimenting with Wine and maybe in a year or two I will have a working environment on a Linux machine that would allow me to switch. We'll see. You have to tread these things very carefully in the work environment (but they let you bitch about them on a blog). IT people and bosses are conservative about everything that could disrupt working solutions. And honestly... $90 wasted on energy hardly pays for more than an hour or two of my time. And that is part of the problem: we waste energy because it is more expensive not to waste it.
"You won't get carpal tunnel from a mouse either."
You will if you have to do EDA (electronics design) on an IBM with touchpad. But that is part of my job...
CTFID (Carpal Tunnel Free Input Devices) suggestions are always welcome!
Well, I confess to drooling over a used thinkpad today, I want/"need" one of those to run EE type things and some software that's Windoze only......
The ISS example has a little flaw: it only takes the gravitational potential into account. What you need to look at is the kinetic energy. An 81kg man moving at 8.8km/s orbital velocity has a kinetic energy of 3.13GJ. Your 5hp motor would need 232 hours to put out that much energy. And as long as we are using rockets to get into orbit, we are losing approx. another factor of 3 on having to accelerate the rocket fuel, as well. Not to mention that the smallest capsule that can keep your man alive is probably 800kgs in mass, so in order to get to orbit, stay there for a little while and live, we need 30 times as much energy with a realistic minimalist's launch system. That's 290 days of the work of the 5hp motor. Well, make that a year...
On the bright side... it is obvious that our energy expense on rocket fuel is negligible. NASA wastes a lot of money, for sure, but it's not on the energetics of their rockets.
Other energy measuement systems:
Emergy:
http://en.wikipedia.org/wiki/Emergy
http://dieoff.org/page170.htm
http://www.energybulletin.net/2331.html (I remember looking at this software when it came out)
http://www.google.com/search?hl=en&lr=&q=sej%2FJ&btnG=Search
Energy as money:
http://www.technocracy.ca/modules.php?op=modload&name=Sections&file=inde...
http://www.technocracy.ca/simp/money-money-money.htm
This is not common, but when dealing with very large energies, why not use the mass equivalent E/c^2? 1 exajoule = 11.13 kg.
The people working seriously on antimatter propulsion for spacecraft are doing exactly that:
http://www.engr.psu.edu/antimatter/introduction2.html
I thought this was nothing but SciFi until I heard a real physics talk about it. It turns out that it is not as far out as one might think.
Its never going to be useful; Run the numbers for conversion efficiency as a fuel.
Beamed power might be useful, nuclear power definately will, but antimatter for storage and conversion just cant be done now or then.
Now if you had some way of inducing proton decay or doing some other GUT effects, you could have the drive you're looking for, but thats a long ways off into sci-fi land; On the other hand its about as realistic as antimatter storage.
"Its never going to be useful; Run the numbers for conversion efficiency as a fuel."
The conversion efficiency does not have to be great because we are talking about a one-of-a-kind application. If you want to get to the Oort Cloud, it does not matter that fueling the spacecraft will cost $1 billion because the overall mission cost will be $10 billion or more just for the 50 year mission support and the science part. By the time this happens (22nd century), a billion will be small change in comparison to GDP.
"Beamed power might be useful, nuclear power definately will, but antimatter for storage and conversion just cant be done now or then."
Let me at least see your back of the envelope calculations in support of your argument before you require me to believe you. Nothing I know about particle physics indicates that it is particularly hard to produce anti-matter. And actually... once you are above the production threshold for a particle, you are automatically above the production threshold of its anti-particle. At energies considerably higher than the production threshold the charge distribution will equalize. The theoretical limit for efficiency is indeed 0.5. Now... since we do not have control over the impact parameter of particle collisions, the resulting outgoing particles are distributed over a vast range of momenta and it is impossible to collect all of them, so we will have to live with a low collection efficiency. Even if the limits of that efficiency are on the order of 10^-3 or 10^-4, large amounts (for propulsion purposes, that is) of antimatter can be produced.
Beamed light, on the other hand is problematic unless you can devote a large interferometric space array to it. A 2m aperture like that of the Hubble produces 80m spot size on the surface of the moon (which is the main reason that we can't show the lunar landing modules to the conspiracy theorists using the Hubble) and a spot of many kilometers at the distance of Mars. For fast communications that is perfectly fine, but for propulsion MUCH larger optical systems are needed. And indeed, focused neutral high energy particle streams might become the railway to the stars, one day, but the technology requirements for that beat current anti-matter concepts, by far.
Nuclear propulsion has also its limits, if for no other reason than the required radiator size and mass. Fission reactor powered spacecaft have real issues getting rid of the reactor waste heat, so we are probably going to be restricted to relatively slowly accelerated ion-propulsion or nuclear steam engines...
See e.g.
http://www.engr.psu.edu/antimatter/Papers/NASA_anti.pdf
for first order requirements on future antimatter programs to be useful to space propulsion. The paper does not look like a clear "no go" to me, espcecially since there is a large scientific interest in building antimatter production facilities in the accelerator community. They will become part of beamline operations at several facilities. To bootstrap a space propulsion program from there is not out of the question. Certainly none of this is nearly as bleak as trying to make fusion economically competitive.
Producing sizeable quantities of antimatter is far beyond current technology. It can be done with various particle beams that can produce a few atoms at a time. Perhaps that can be scaled up by orders of magnitude, but perhaps not for awhile. In any case, with any sort of current technology you're talking about creating at best a few watts of power worth of anti-atoms a day, with a conversion efficiency that is likely less than 1.0e-8. Use the LHC for 50 years and maybe you'll get enough to do something, but probably not enough to explore the solar system.
The real problem is that accelerating a particle to relativistic velocities has terrible efficiency, even if the collision and collection wasn't that bad. Beyond efficiency though, it's expensive to build the accelerators, and to run them. Power bills are the least of the problems.
"Producing sizeable quantities of antimatter is far beyond current technology. It can be done with various particle beams that can produce a few atoms at a time. Perhaps that can be scaled up by orders of magnitude, but perhaps not for awhile."
Don't underestimate modern accelerator technology! Much of the improvements in recent decades went into beam current rather than energy and we can technologically produce beams which have a power on the order of 1-10MW at a few-few hundred GeV these days (with average beam currents from 100uA-10mA or more) with very high driver efficiency. If the anti-matter production efficiency can be brought up to 10^-4, which I believe it could, such a beam would accumulate anti-matter worth hundreds of W to kW. Accelerators of that kind can run for many years in close to continuous operations and the total energy collected in a year is far more than you would want to keep around in a single chunk of anti-matter anywhere near people... the explosion in case of a containment problem would equal that of a serious chemical explosive devices... except that the energy gets released mostly as hard gamma rays - the perfect "neutron bomb"! And with 10^-3 collection efficiency we are getting into the kTon range explosives/year. Finally, a 10MW, 1% collection efficiency facility could make the equivalent of a small fission device. 10MW is not a whole lot of power to operate such a facility. At 15cents/kWh, the hourly cost is only $1500. Physicists and engineers get $40-$60/hour these days. 10MW therefor equals no more than something like 30 people, not nearly enough to operate the facility!
"Use the LHC for 50 years and maybe you'll get enough to do something, but probably not enough to explore the solar system."
The LHC is designed to be a storage ring for TeV protons/antiprotons and the most important quantity is accumulated cross section for the event types of highest interest, which greatly depends on beam quality since we are talking beam-beam collisions, not fixed target experiments. Therefor the accelerator is built as a precision machine, not a giant medium energy beam gun. Still, the total energy in the beam is very high already... so high, actually, that a single beam loss will result in very serious physical damage of parts of the storage ring. If it happens in the magnets, they can be replaced, but if it were to happen anywhere inside the detectors (ATLAS or CMS), the experiment would be dead for years because the most expensive parts of that detector would have to be rebuilt. Accelerators which are built for beam current and power look more like SNS:
http://www.sns.gov/
Trust me... you don't want to be anywhere near that sucker and its target! In comparison, you could safely walk around (not across, of course) the injector proton beam lines at CERN. (And actually, I did, many years ago.). That is not true for LHC, either, but the new generation of high current beam lines is absolutely brutal, so bad actually, that the target lifetime is the main limiting factor! SNS uses a liquid mercury target inside a double walled vessel which has to be replaced a couple times a year if I remember correctly.
The potential usefulness of antimatter concepts for initial mission designs points to small probes very much like New Horizons. The goal is to have fuel/propulsion units that would have ten times the specific impuls of chemical propulsion systems. The mission profile of inter-planetary probes with a few tons of mass could be greatly enhanced by such a system. It's not so much the total amount of energy that counts as the total delta v that the mission can expend to seek targets. I believe that ten times delta v gives 100 times the area coverage, i.e. 100 times the discovery potential for a mission that flies through the outer system.
The way I look at it is that if one was willing to give some credibility to fusion in the early years, one can as well cut the antimatter guys some slack. They are up against much smaller and easier to solve problems.
Why do I have to do everyones math for them?
http://livefromcern.web.cern.ch/livefromcern/antimatter/everyday/AM-ever...
Modern particle accellerators have efficiencies of 10^-8 or worse... Say you do better by 1000 fold, what do you get?
A compact energy source is all, and that will likely be eaten up to less than gasoline with enormous confinement devices to store the gunk. You propose giant storage rings that hold about as much energy as will power a 100 watt bulb for a few seconds?
Next, follow the rocket equasion. Assume that through some series of miracles you can manufacture antimatter efficiently enough and store it, and your losses are only in the thousandfold instead of the millions or worse. The power requirements for a rocket scale with the square of the efficiency, so if you want to do the strate photon drive thing you're going to need a gigawatt for just 3 newtons of thrust... If you used all the power output of modern civilization after your 10^-3 losses through unknown antimatter production and storage miracles, you're down to 30 newtons of thrust... Its just not gonna fly.
Otherwise you just heat a reaction mass, and you might as well just use ordinary nuclear then... A nuclear salt water rocket, some VASIMR clone, a variant of any open cycle gas core nuclear rocket...
You're proposing devoting all of modern civilization's power output to 30 newtons of antimatter power and a large space array for beamed power makes you balk? In all seriousness though,
Well, its not wrong, but its not right either. Open nuclear cycles such as nuclear thermal rockets and the nuclear salt water rocket, gas core nuclear light bulbs and the like dont require radiators because the propellent dissapates the waste heat. For VASIMR and other electric rockets, sure you need big radiators, but the size is proportional to the fourth power of the temperature of the heat rejection, so jacking up the temp of the radiator gets you a long way. You lose some efficiency, but oh well. Thats why space reactors have to run hot.
Its still far cheaper than antimatter storage rings and production facilities that wont ever exist. I strongly suspect that there are theoretical boundries for antimatter production yields in the same way that there are theoretical boundries that prevent electrostatic fusion from ever yielding net energy.
As for electric propulsion, VASIMR is tunable in efficiency along the parameters of the rocket equasion, so its pretty desirable for spaceflight in general.
As bleak as fusion is, its still got a far higher chance of competing than antimatter rockets. The only place antimatter will be seen in propulsion is antimatter catalyzed fission/fusion, and then probably will just be produced on demand with a cyclotron rather than some storage mechanism.
"You propose giant storage rings that hold about as much energy as will power a 100 watt bulb for a few seconds?"
Huh? A modern storage ring like LHC holds 725 MJ of energy. That would power your 100W light bulb for 84 days, not just a few seconds. You are off by five orders of magnitude here. Just like in some of your other estimates.
Nobody seriously proposes antimatter storage in storage rings for spaceflight. Where did you read that nonsense? Or did you just make it up?
"A compact energy source is all, and that will likely be eaten up to less than gasoline with enormous confinement devices to store the gunk."
What does antimatter propulsion of spacecraft have to do with gasoline? We are talking about a one of a kind application, not about moving your car.
"The power requirements for a rocket scale with the square of the efficiency, so if you want to do the strate photon drive."
Antimatter engines do not have to be photon drives. This is not about a delta v of 0.4c but about delta v of 10-100km/s. Please read up on what these people are talking about. You are completely missing the point here.
"Otherwise you just heat a reaction mass, and you might as well just use ordinary nuclear then... A nuclear salt water rocket, some VASIMR clone, a variant of any open cycle gas core nuclear rocket..."
Except for the little issues with cooling the core. And the enormous launch mass etc.. We are talking about building lightweight spacecraft in the few ton range here, not SciFi behemoths with tens of thousands of tons. Again, you don't seem to get what any of this is about.
"You're proposing devoting all of modern civilization's power output to 30 newtons..."
Actually, I am not. You are. Maybe you should read that article, first? It might help to sort out the conceptual framework this lives in.
"Open nuclear cycles such as nuclear thermal rockets and the nuclear salt water rocket, gas core nuclear light bulbs and the like dont require radiators because the propellent dissapates the waste heat."
And they have not been built, yet, either. It is not clear to me that they can be built or even launched with any technology that's on the near horizon. These things are at least as speculative as antimatter. On top of that they are highly unimaginative from both a physics and an engineering perspective. It's the attempt to break physical limits by throwing dull ideas at marginal concepts. Vasimr for instance buys you very little in the real world, just like continuously variable sub-super-hypersonic jet engines look great on paper but have not been even worked in the lab.
"Its still far cheaper than antimatter storage rings and production facilities that wont ever exist."
You could build all of LHC again for the cost of a few days of Iraq II. You need to get a perspective on what these things cost. A brand new anti-matter facility will cost no more than a few launches of the space shuttle. It's just magnets, vacuum and high voltage, you see. None of that is very expensive, even if it looks impressive. The smarts are in HOW you wind that wire and HOW you shape those magnet cores and resonators. Smart things are never very expensive to reproduce once you have them figuered out. Only blatantly dumb things like useless wars are. Unlike our politicians and wars, particle physicists and EEs have the accelerator game under control.
"As bleak as fusion is, its still got a far higher chance of competing than antimatter rockets."
I doubt that antimatter rockets will have any competition, whatsoever, if they work at all. You see... they don't do much, don't need many moving parts AND they use the most energetic fuel possible. They are the ultimate power tool for their application... and nothing else.
"The only place antimatter will be seen in propulsion is antimatter catalyzed fission/fusion, and then probably will just be produced on demand with a cyclotron rather than some storage mechanism."
You sound like you don't know what a cyclotron is and how it differs from a synchrotron and what the difference between that and a pure storage ring is... and what these things are good for. OK. I give up. Bashing your knowlege/ignorance of beamline technology is not useful. Just go and read up on some of this stuff.
OK I really like the old Cubic Mile Of Oil, with the obligatory Eiffel Tower next to it, hehe.
Even the most die-hard cornucopian has to admit that's a hell of a lot of oil.
"Even the most die-hard cornucopian has to admit that's a hell of a lot of oil."
A real cornucopian will simply not care about anything you have to tell them, no matter how polished the presentation. No religious fanatic ever does. Forget about discussing them and get to work on the real problem!
Now. The adult response to the CMO presentation is to completely deflate it:
"So? How much of that was put to good use as compared to being burnt in oversized SUVs and poorly insulated homes? Come back when you have stopped wasting the good stuff and then tell me how much more you still need to replace!"
I think the first step in every addiction recovery program is to admit that there is a problem and that the problem is not that the world is so dark and bad and unfriendly but that it is ones own addiction that makes it look that way. As a society we haven't even made that first step, yet. None of the following steps are going to be succesful without this first one.
Doomers are an even worse fanatical religious group.
FWIW, the chemical structure of coal is apparently complex, highly variable and somewhat unknown (in response to the query above about carbon and hydrogen in coal vs. crude).
Wikipedia Coal
For one graphic of a chemical structure of coal, see: Coal Research Tutorial: The Properties of Coal Macerals Chemistry Division, Argonne National Labs (lots of ring structures linked together in complex ways)
Comments from "Profiles: Studying the structural chemistry of coal" (2 page PDF):
The chemical structure of coal exists as much as the chemical structure of dirt. They are both mixtures of a multitude of components of very different chemical composition. For someone who wants to burn coal it does not matter, anyway. What matters are questions like
"How much heat comes out per ton?"
and
"How much sulfur do I have to bind?"
and
"How much ash do I have to dispose off?"
and finally
"How much GW am I going to cause?".
After we will be done with burning coal on this planet a century or two from now, there will still be billions of tons of "samples" left for chemists to analyze the hell out of. If they will really care... which is highly doubtful.
ash is not disposed of : ash is used in concrete mixtures as a replacement (up to 20 %)for portland cement. in fact federal highway paving projects require that concrete mixtures utilize fly ash ( at least during the summer months).
fly ash improves the quality of portland cement concrete ( although some "old timers" will disagree)
1) fly ash works as a water reducer
2) fly ash is a pozilon (improves the bonding between the cement paste and aggregate)
The cubic mile picture may also very well illustrate the amount of coal we burn. Even the color is the same. But we'll need to add another one, half its size by the big one:
World coal production is ~ 6 billion.short tonnes = 5.4bln.metric tonnes. (damn unscientific units!)
Coal specific density = 833kg/tonne (bituminous, broken - the bulk of what is burnt in coal power plants)
Volume of coal = 5.4*10^9*1000/833 = 6.5 bln.m^3 = 1.55 cubic miles.
So, we are burning 1 CMO and 1.55 CMC yearly.
I like the metric system except when it comes to measuring time in hours, noting that 1 hour = 3.6 kiloseconds. Hence a kilowatt hour is 3.6 megajoules. A quick way to exactly multiply by 3.6 is to double a number, double it again and subtract 10%. To approximately divide by 3.6 first add 10% then halve then halve. Examples
for 27 X 3.6 the sequence is 54, 108, 97.2
for 27/3.6 the sequence is 29.7, 14.8,7.4
Also notice that athletics uses metres per second eg wind assist in the long jump. Maybe the suburban speed limit shouldn't be 36 mph or 60 kph but rounded to 17 metres per second. It might help judge braking distances.
Heaven forbid! I hope you are not suggesting they start using a custom time measuring system in UK/USA too. How many feet do you go if you are traveling by 35 miles per (US)kilosecond for 5 (metric) minutes? How about that? :)
Beats furlongs per fortnight.
Barrels, quads, btu:s, gallons and so on, may these funny units die out.
Thanks, HO. Wonderful information, and expalined well. Just in case you ever visit small town Arizona, "Quads" are not energy units, but...ATV's [all terain vehicles].
If 100 million of our US population got on stationary bikes to generate electricity, we could produce power at the rate of 10 MW. Power Co-Op?
There's a fascinating 1-page article in a recent issue of IEEE Spectrum magazine.
In order to describe energy consumption in easily comprehensible units, they used yearly world oil consumption as a standard. The world consumes roughly 1 cubic mile of oil per year. They then calculated the equivalent in other energy source. It was jaw-dropping.
To produce the same power via hydro-electric, you'd have to run 4 3 Gorges size dams for 50 years. For solar, you'd have to have about 93 million 2.1 Kilowatt panels running for 50 years. They also had nuclear and wind, although I don't remember the values for those.
how about the good old slave unit?
a 2000 daily calories diet would be a rough 100Wh per hour...
see the slave equivalent per usage:
http://www.manicore.com/anglais/documentation_a/slaves.html
and about the Cubic Mile Of Oil, i would consider the mass rather than the volume. the former stays constant (in classic physics at least). which allow some basics: log=ashes+smoke.
see that Cubic Mile Of Oil? at the end it will end up either in a landfill or over your head. (ask your children which way they fancy the most)
Drumbeat hasn't been posted for Saturday yet but here is a link to a very good audio lecture on global warming and mitigation by David King who is chief scientific adviser to the UK government and head of the Office of Science and Technology. He is a professor of chemistry at University of Cambridge.
http://www.globalpublicmedia.com/lectures/835
The first part is a very good overview of the science behind global warming and where we are at. The middle part is UK specific. He finishes off with an update on the discussions going on between governments. If you want to know what policy initiatives are coming your way from your government then take a listen. By the sound of it there is a lot going on.
IMHO he puts too much emphasis on flooding and none on the effects on food production. Also no recognition of PO. Just 2000ppm of CO2 from burning all known hydrocarbons. TODers will know that PO and global warming are two sides of the same coin and I've felt for some time that the wonks see it that way. They don't need to ask what oil reserves are. They just read your mail.
Much as I can't stand Tony Blair's or his Labour Government, this guy is well worth listening to. Who wants to read on a Saturday anyway?
I'll repost on Drumbeat when it comes up.
You guys really know your stuff. Very impressive! I think the world should finally give up on the ancient measurment units and fully adopt the SI or metric system. All energy should be discussed in nothing but SI units, sure would be simpler that way. At least then we would all be speaking the same language. What do all of you think?
I'm with you 100%. It is crazy to have to define which particular meaning of a word you are using. The article itself says, regarding the size of a barrel, "remember that it is 42 gallons and not 55", and even that is not the end of the confusion: is that US gallons or Imperial gallons? The two are very different. Even "US gallon" has different meanings, as there is a US liquid gallon and a US dry gallon!
Gallons, pounds, miles - these all have multiple meanings. Isn't it a grand bit of US exceptionalism to not use* the measurement system that 95% of the world's population uses**? The true irony is that even the Old Imperialists (Britain) have mostly moved to metric, though the rebels of 1776 cling to the old system. (Along with Liberia and Myanmar).
*Except for scientific use
**Most use metric exclusively, some are still "bilingual", e.g. UK, Canada
Then there are the insane modifiers. Inconsistent usage related to oil leads to confusion. I mean, really, "m" for thousand, "mm" for million"? Or is it "MM", I've seen both. Shouldn't MM mean million million (i.e. 10^12)?
Even abbreviations are ad hoc. "lbs" for pounds, due to the Latin for scale?
Now, having criticized the Imperial/US/whatever-you-call it measurement system, I should note that SI usage is not exactly consistent either. km/h rather than m/s, kWh rather than J, Hz rather than 1/s, t as a special symbol rather than Mg (1000 kg - also known as a tonne, hence the "t"). Still, there is no confusion, as there is always only one definition for the unit. Knowing the meanings of the abbreviations you can work out what different units mean - for example, a Watt (W) is defined as 1 Joule per second, hence 1 kWh = 1 (kJ/s)*1h = 1 kJ * 60 * 60 s/s = 3600 kJ = 3.6 MJ. It may not be trivial, but you can do it, without knowing anything more than the definition of a Watt. Unfortunately no matter what you do the measurement of time is not going to fit into a decimal system as the rate of revolution and speed in orbit of the planet aren't things we can choose.
The time issue is a formidable one as is the US's emotional attachment to the ancient US Customary unit system. Well it's not even a system just an accumulation of units of the ages. There is a proposal for metric time out there that, at least in part, is quite amazing in its application. I know a little about it but not enough to plug it properly. It goes something like this: Instead of 24 hours we would adopt a 10 hour day each with 100 minutes each with 100 seconds. Oddly enough, the seconds come out to be fairly close to the ones we have now. There are unique problems and solutions with this system. Google it to find out more.
More practically, I think we should focus on the full adoption of the SI in our personal daily lives. I already have switched over as much as I can. I refer to my own mass and height in SI units. I record fuel purchases and fuel economy in km/l. I convert car specs into SI units like kiloWatts and km/l etc. for comparison. I refer to all temps in Celsius. It is not hard at all. We should try to propagate its use professionally and through the government by demanding a federally funded mandate to change over the US by 2010. This would alleviate many problems and make the US more competitive in the world marketplace. Maybe it'll alleviate some of our trade deficit and get some of our jobs back from foreign countries smart enough to use the same system as 95% of the people that want to buy our stuff but don't because it doesn't fit the world system. It's time we get smarter.
It sometimes works out OK with the tonne (1000kg) and standard ton (2240lb?) being close in mass. I've even heard 'megagram' for tonne which is a bit pedantic. The former British colonies make it harder sometimes with fuel consumption not km/l as you suggest but litres per 10 kilometres so smaller is better. Brits still sometimes measure their body weight in multiples of 'stone' of about 6.5kg eg in a phrase like 'nine stone weakling'.
It's strange on US sitcoms when a TV character says 'put on your coat coz it's 35 degrees outside' or the outdoorsman risks near certain death in -2 degrees. When the US goes metric the world will be very different. The last big holdout will be tyre (tire) pressure not 35 psi but 250 kilopascals.
10 (new)hours of 100 (new)minutes of 100 (new)seconds is 100,000 (new)seconds per day.
24 hours of 60 minutes of 60 seconds is 86,400 seconds per day. That's why the two are close.
Changing the definition of the second, however, changes every SI unit based on time. It's one of those things that would have been nice but it's way too late to change it now. Heck, look how many places still use the massively confusing AM/PM 12-hour let's-start-counting-with-12-in-place-of-zero system. A universal 10-hour day is about as likely to succeed as a universal human language (Esperanto, anyone?)
I have a basic objection to the SI system: it's based on a decimal system, which is a big pain.
The french actually tried a decimal calendar for 10 or 15 years, until Napoleon was defeated. They were in love with decimal.
Our time system is roughly base 12, which is much more convenient. Think of 3 daily shifts divided using a decimal system. No 8 hour shift - no, instead you have 6.6666666 hours!
A 60 minute hour can be divided by 2, 3, 5, 6, 10, 15, 20, and 30! A decimal system has 2 and 5 as divisors: that's it!
The foot is base 12: much more convenient. The mile is 12 x 440, which provides lots of divisors.
The gallon is 2 to to the 7th ounces: a base 2 system, long before computing produced the kilobyte: 2 to the 10th bytes. Much more convenient for many uses.
I have to admit the standardization of the SI system is ultimately more convenient, but I think the old measures deserve more credit, especially for use in a pre-calculator/computer age.
To add some confusion here, I know it's historically called the British system, but the British no longer use the British system. We adopted the US system over 20 years ago. Quadrillion is not a word in regular use, but we use the US meanings for billion and trillion. Some other English speaking countries (Australia?) may still use the British system, as do continental Europeans. The French in fact invented both the US and British system.
I favour SI units ;)