More on the Units of Energy
Posted by Heading Out on January 19, 2007 - 10:42am
Topic: Miscellaneous
Tags: barrel, bbl, btu, eia, oil, oil prices, peak oil, quad [list all tags]
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
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.