The Cogeneration Stopgap
Posted by Engineer-Poet on February 26, 2008 - 11:00am
Topic: Demand/Consumption
Tags: cogeneration, efficiency, entropy, V2G [list all tags]
The prospect of going through a cold winter with inadequate heat is a real one. More and more Americans are putting their winter heating fuel on credit, increasing their level of debt and the burden of servicing it. This cannot continue indefinitely. When the ARM resets or the credit cards max out, the whole house of cards (including paying the mortgage) falls down. Foreclosure is the problem in the mid-term, but freezing strikes as soon as there's no fuel for the furnace.
This problem is made much worse by fuel shortages and the consequent price spikes. As fuel supplies go down, prices go up. The alternative is rationing, but this has costs too; if commerce is shut down, employees don't get paid and the problem of paying for heat is much the same.
The problem comes down to affordability. Whether there is a limit to the gas available, or if incremental supplies command unaffordable prices, the alternatives are to do more with less, or do without. As N. American gas supplies are already shrinking, any good solution has to involve getting out in front of the problem and staying there.
So what can we do?
In the end, natural gas will be too expensive to burn just for space heat. The obvious long-term solution for most areas is a combination of superinsulation and passive solar design; if you need no fuel, you don't care how much it costs. Does anyone care about the cost of spermaceti anymore? But that's a 50-year goal; the immediate problems are going to center around keeping existing buildings warm and lit until they are finally renovated or replaced.
If we have a relatively fixed building stock and a declining supply of gas for heat, the problem becomes one of getting the same amount of heat out of less fuel. The big question is if we can do that, and how?
Can we do it? I believe the answer is "yes".
Why should you believe me? Because I see a way for it to be done. The technologies have been with us for decades, though newer ones will improve the performance. It's attractive enough that some businesses have been moving this way for years; all we have to do is accelerate the existing trends.
How do we do it? In the longer term, we replace natural gas with electricity. But this takes a relatively long time to plan and build generators, transmission lines, and so forth. In the short term, we do jiu-jitsu with entropy.
The nature of the fix
Getting into the details requires a discussion of entropy.
Entropy is a rather arcane concept, and hard to grasp without at least an introductory course in thermodynamics. I'm not going to ask that of readers here, or take the time and space for the digression. I'm just going to ask you to accept three things:
- That energy is conserved; any energy in a system came from somewhere, and can neither be created ex nihilo nor disappear.
- That energy in the form of work (turning a shaft, electricity) is more useful than energy as heat.
- That work can be used to move other energy around in useful ways. One is to push heat from a lower temperature to a higher temperature.
How does this help fix things? It helps if I restate the problem.
The nature of the problem
We have a lot of building stock which was constructed with relatively poor insulation and little attention to passive heat gain and thermal mass. Most of this building stock is heated by burning fuel in an open flame at a couple of thousand degrees F, then diluting the heat down to a comfortable temperature.
This dilution of heat involves an enormous increase in entropy. Allowing an increase in entropy means throwing away an opportunity to do useful work. What kind of useful work could we want? Simple: we could use some work to push more heat (a lot more) to where it does us some good! And how do you do that? A few pictures might help:
Here is house #1. It needs 45 million BTU of heat per year to stay warm in the winter. If it is heated by a condensing gas furnace at 90% efficiency1, it will use 50 million BTU/year of gas (and 5 million BTU goes up the chimney). At near-future prices of perhaps $1.50/therm (100,000 BTU), the gas will cost about $750/year. As natural gas supplies shrink, the price of natural gas will tend toward parity with the price of oil. Oil at $100/barrel is roughly $1.70/therm; since natural gas is interchangeable with oil for some purposes, we can expect this to be a price floor relatively soon.
90% efficiency may sound like a lot, but it isn't in this context. The gas furnace is essentially taking the expensive energy as high-temperature heat and, by diluting it, immediately throwing a great deal of its usefulness away. We don't have to do this. What we want to do is take the fuel and extract some of the energy as work; we can use the waste heat for heat, and the work as the muscle for our jiu-jitsu. Climate Energy even has complete systems for sale; not the exact specifications desired, but proof that it works.
Climate Energy's cogenerator efficiency is our major point of interest. They claim 18.5 thousand BTU/hr in to get 1.2 kW of electricity out (about 4100 BTU/hr of electricity). This is a thermal efficiency of about 22%. Losses come to another 2400 BTU/hr, or about 13%. The losses are a bit high (probably due to the design), but the efficiency seems about par for an engine of that size.
When the heat demand goes over 12,000 BTU/hr, the Climate Energy system has to fall back to a conventional furnace. This sacrifices the advantage from cogeneration. We can improve the system efficiency with two changes:
- Making the engine bigger, to supply all heating demand from the engine and reduce heat losses to the cylinder walls.
- Using outside air to feed the engine and recover latent heat in the exhaust.
Assume that we've got it. What do we do with it? Using this in just one house wouldn't help. Gas demand would go from 50 million BTU/year to 75 million BTU/year per house. How does this improve matters?
Sharing is caring
The twist comes when we get to houses #2 and #3. In the process of heating itself, house #1 would generate 22.5 million BTU (6590 kWh) of electricity. Electricity is energy, but it isn't just some random form of energy; it represents work, which is far more useful than heat. As a matter of fact, it can be used to push heat from colder temperatures to warmer ones using a heat pump. The best heat pumps can achieve leverage of 4:1 and more (HSPF of 13.6 or greater).
House #1's cogenerator makes 6590 kWh of electricity, or 22.5 million BTU worth. House #2 needs 45 million BTU of heat, but its heat pump only needs 11.25 million BTU of electricity (3295 kWh) to supply it. The surplus passes on to house #3, which is completely heated by the remaining 3295 kWh. We're now heating three houses on the gas that it formerly took to heat one and a half; given that it would have taken 150 million BTU to heat all three houses using gas furnaces, the net reduction is 50%. At $1.50/therm, the total cost of heating all three houses is just $1125/year, or $375 each. The reduced demand for gas will help hold the price of gas down. If oil goes to $200/bbl and natural gas prices follow suit, gas will cost about $3.45/therm and the combination of cogeneration and heat pumps would save about $2600/year.
I hear you saying "Wait! You can't make 135 million BTU of heat out of 75 million BTU of gas!" You're right; there is something missing from this diagram. The part that isn't shown is the 67.5 million BTU of heat taken from the outdoors by the two heat pumps and pushed indoors, courtesy of the capabilities of energy in the form of work. Energy is conserved throughout. Entropy also increases at every step, satisfying the Second Law of Thermodynamics.
What would this cost? In mass production of several million units per year, I suspect a cogenerator could cost as little as $2500 (this is about what a much more powerful car engine, with 4 times as many cylinders and much more complexity, costs). A single-cylinder engine making 6 kW of power at 30% efficiency would generate 14 kW (47,800 BTU/hr) of waste heat. One such engine could replace a small-size furnace. If the price of natural gas is equivalent to $200/bbl oil, the cogenerator would pay for itself in less than 5 years.
Half a loaf will get you to the store
The final objection, and also valid: "This only gets us halfway. Once gas supplies fall below 50% of today's, we're stuck again."
That's true as far as it goes, but nothing happens in isolation:
- We can get better than 30% efficiency. Delphi and other companies are working to make solid-oxide fuel cells for automotive use. These are already achieving efficiencies in the neighborhood of 50%. At 50% efficiency, one house with a fuel cell can power FOUR houses with heat pumps, and fuel demand falls another 20%. Even 50% isn't the limit; direct-carbon fuel cells (DCFC's) can turn charcoal into electricity with efficiency as high as 80%.
- The cogenerator is (remember the title?) a stopgap. Cogenerators can make up the difference between the rapidly-increasing power needs of heat pumps and the slower increase of other electric generation (esp. renewable generation), the decline of gas supplies and the renovation and replacement of the building stock. We will probably spend the next 10 years installing engine cogenerators, another 20 years building fuel cell cogenerators to replace worn-out engines, and the last 20 years phasing them all out as the building stock gets updated.
Can we build this many cogenerators? It looks easy. The USA currently buys about 17 million light vehicles per year, and 99% of them come with some sort of piston engine. Many of these engines have 6 or more cylinders, and can produce at least 100 horsepower (75 kilowatts) per engine. There are roughly 50 million buildings heated with natural gas; converting 10% of them per year would require just 5 million cogenerators. If each cogenerator has one cylinder producing 6 kW, this is about 5% as many cylinders and less than 2.5% as much power as each year's vehicle fleet.
Other twists
Nothing happens in isolation, and the cogenerator/heat pump scheme would be no exception; it would be intimately connected to the electrical grid, and by extension it would connect to everything else that's plugged in. The effects snowball, and they're all good:
- Any other source of power offsets demand for natural gas; if houses 1-3 have wind power available 30% of the time, about 5900 kWh (1/3 for the heat pumps, 2/3 for a resistance heater to substitute for the cogenerator) would cut gas use by 30%. If off-peak wind power costs 4¢/kWh, this would use $236 of electricity to displace $338 of natural gas at $1.50/therm. If natural gas climbs to $3.45/therm, the wind would displace $776 of gas.
- Electric vehicles or PHEVs could be charged from the extra generation resource; shortage of electricity would be put off for quite some time.
- Adding to #2, displacing petroleum from motor fuel would allow it to be used as heating fuel... in cogenerators, further extending the supply of both heat and electricity.
- Adding as much as 300 GW of cogeneration to the grid, most of it within a block of the point of use, would add stability to the grid and slash transmission losses.
- Any community with enough cogenerators would be able to operate as an "island" during a winter grid outage, making power interruptions far less troublesome. Given electric vehicles with V2G capability, these islands could be as small as one house.
As you can see, there are many reasons to start on this path now.
Summary
A large part of the USA needs heat in the winter, and much of this is supplied by natural gas. N. American gas supplies are shrinking rather rapidly, so we must do something about it for both the long and short term. While we wait for the building stock to turn over, the combination of cogenerating furnaces, heat pumps and other grid-connected devices can shrink our total fuel demand, allow us to make substitutions much more easily and turn big problems into minor inconveniences. If we want a warm, clean, secure and affordable future, this is a good place to start.
Footnotes:
1. 90% is on the low end of efficiency figures for condensing furnaces (which go up to about 97%), but it makes the numbers neater. The broader conclusions are the same.
2. These numbers are also chosen to make the arithmetic come out more neatly; small changes make small differences.
Further reading
Ground Source Heat Pumps, by Heading Out.
Really unbelievable, even heating oil is bought by credit. Here in Europe it is just unthinkable.
One has to ask: What kind of goods can you NOT buy by credit?
What about taxes? Can you pay taxes by credit?
I have not heard of a Gov't that takes credit card directly but since credit cards will let the holder obtain a "cash advance" and many cards now supply you with cheques you can write which clear through to your card balance then the answer is "yes" you could pay taxes by credit card.
California accepts credit cards for personal income tax.
I have heard that old people in California can have the city put a lien on their house for the value of property taxes instead of paying property taxes. With property taxes of 1% of the house value and "house value" increases of only 2% per year (due to proposition 13), a house just increasing at the rate of inflation shouldn't have too much difficulty maintaining additional yearly liens until the owner dies.
Well, as a matter of fact, the IRS (US Federal Tax Collector) DOES take credit cards, through some officially sanctioned 3rd party providers.
Here is the link: http://www.irs.gov/efile/article/0,,id=101316,00.html
Yes, things are a little whacked around here these days. There was an article in this morning's newspaper about 'payday lenders' who take postdated checks as collateral. There is a proposal to limit them to 45% APR. Currently it is over 300%!!!!!!
Euro,
In the USA, you can buy any goods and services with a credit card. Some smaller businesses require a minimum purchase, such as $10.
I buy nearly everything (but not my heating oil) with a credit card, but pay my bill in full every month, so that I am not carrying a balance or subject to interest charges. Many people are not so conscientious. Average credit card debt continues to rise. It may be the next meltdown.
It might be a variation on, "They pretend to offer government services, so we pretend to pay our taxes."
(not sure of the relevance to co-generation...)
Chap here who supplies firewood has decided to take cash only as there have been too many problems with cheques. But then again maybe has just made an exception in my case:)
If people are having difficulty paying to operate current heating systems, how will it be possible for them to pay to replace those systems with alternatives? Almost all replacements have an up front cost in excess of expected future savings.
I have long said that once we pass peak, there will be insufficient energy to invest in the infrastructure for any alternative, even if there is an infrastructure that can come close to working. So here we are now, not clearly in production decline yet, and some people are not even able to provide themselves with necessities like heat in the winter. Insufficient energy to fuel our economy means the economic pie shrinks, and adequate heat in the winter is part of that economic pie. Over the span of the oil age we progress from improving living standard to stagnation to conservation to deprivation to death; we are somewhere between stagnation and conservation.
If there are future historians to describe the industrial age it will be noted that we squandered the planet's energy saving account on trinkets with no consideration of reinvesting it in the future.
This winter I have seen for the first time that people in Colorado, USA are beginning to wake up to energy issues, and it is not the cost of gasoline, but rather the cost of natural gas, heating oil and propane. I live in a rural area that is predominantly heated by propane, and in nearly every conversation the $3.00/gal cost comes up. Lots of 'propain' jokes flying around. I have been using propane for 20 years, and in that time the cost has gone from 50 cents to three dollars. Obviously if the price rose to 18.00 a gallon in another twenty the majority of people would be freezing. In a cold January I use 125 gallons, even though I have an efficient passive solar house and keep the thermostat at 62F. I also have a fireplace and a wood pellet stove. Wood pellets at $225 a ton are much more economical than propane.
I have heard the same stories from people in town who use natural gas, and people back east on heating oil. People are really paying attention. Of course, if you don't have the money it is difficult to retrofit new technology, but there are a lot of cheap things that can be done, like weatherstripping, covering windows with plastic, and lowering the thermostat.
It is a shame that all this sub prime stuff occurred for lots of reasons, but one big one I can think of is home energy improvements. If you refinanced to install a GSHP and/or solar thermal system, you can deduct the interest as a home improvement and enjoy the savings right away. Lots of people would rather pay as they go, but some can see the wisdom of some "energy insurance". When these improvements are carried through to the value of the house at resale, they really catch on.
Yes, Henry, we're at the Peak, yet we have significant numbers of people barely getting by. And that's the whole idea. To whatever level one is able to consume, one is to wholeheartedly fulfill that degree of consumption. And we make it easy: simply select the largest house, vehicle, and TV that you can just barely afford. Everybody's doing it - it's the Amerikan way.
We're probably at peak food as well, yet in absolute numbers there have NEVER BEEN more starving people. Peak money, yet billions scraping by.
This is where the cornucopian/futurists fall down. If we can't do it in the best of times, even though we could, why think we'll do it in worse times? I've never seen a reasonable answer to this question.
As things get worse, they'll get worse.
Background: I'm not a cornucopian by any stretch of the imagination, I think we're in for some very big pain (USA in particular, but the whole globe will feel it)
That said, I disagree that just because we can't do it now at peak, that nothing can be done in the future.
Where there is a will there is a way.
Right now, the will is lacking. The pain hasn't gotten bad enough yet for most people. Everyone is just scraping by, with most people believing (misguidedly) that it is just "temporary". That they can pay with a credit card, and that somehow magically things will be good enough later that they can pay it off. But as the pain gets worse and stretches from months to years, more and more people will come to realize it is not temporary - that due to various factors including but not limited to peak oil (e.g. intentional monetary inflation/debt deflation by the gov't), their standard of living has been drastically reduced. This will induce a lot of motivation (that will thing again). That motivation can be used towards bad (like theft, war, etc), but can also be used towards good (like getting politicians in office who will support real solutions to the problem, and figuring out how to address these problems on a local scale).
When motivation is sufficient, it is quite likely that there will be many communities that will come together to figure out solutions to these issues, implementing things just like what the article describes. That doesn't mean things will be good everywhere - there could be whole regions of the globe (and of N. America) where things break down, because people fail to figure out how to work together, instead continuing to see only their own selfish short term interests. But it seems unlikely that this will be universal.
So I suggest to all the doomers that post messages like this, to get out in your local community to promote these kinds of solutions, especially as things get more difficult. You may find that people's receptivity to such ideas drastically change as the reality sinks in as to the world of economic pain we're headed towards. It will also help when the facts of peak oil intervene to convincingly debunk sites like "PeakOilDebunked". It may take time, but it will happen.
Morgan
BTW - I am eating my own medicine, I have started a local business promoting alternative transportation using electric bikes and sports utility bikes. I am doing this on top of a full time job, and risking my home financially, because I believe it is the best thing I can do to help address the situation.
The 70's were a bleak time and yet towards the end of the decade when the price of oil soared MPG went way up. why can't that happen now with cars or furnances? not everyone is broke, don't overstate your case.
Sorry, john15, but got2surf never said everyone was broke. You did. You made up that straw man argument. Try again. You get a big fat "F" for that one.
than who is the "we" he stated. he should have said "some." again, not everyone is broke. same as we don't buy everything from china and we have record exports. yes there are problems, but don't overstate it. some people are doing good and some people are doing bad at any time. some people will do fine and some people will struggle.
speaking of straw man, who are the futurists/corns who said that things were good? certainly not people like me who know wages have been stagnant for a decade or so and inflation is higher than the CPI numbers.
greyzone- here is another example.
"And we make it easy: simply select the largest house, vehicle, and TV that you can just barely afford. Everybody's doing it - it's the Amerikan way."
everyone's doing it? again, don't overstate your case.
And my goodness, are there no work houses, are there no prisons? Gee, doesn't anyone have any statistics on the fine increase in housing for the marginalized? You know those bleak houses where everyone who falls by the wayside goes green, institutionally speaking that is? Does the last man standing outside those walls gets to throw away the key and drive off in his Maserati? No need for anyone to worry about miles per gallon then.
Interesting, isn't it? To watch a pond drain and see all the little critters in the still deep pools swim about, faster and faster, while at the edge they thrash about and die.
why can't that happen now with cars or furnances?
With 95% efficent pulse furnaces - how much 'waste' do you think exists?
RTFP, it's explained above.
Roughly 50% of the "availability" (ability to do work) is wasted with a pulse furnace compared to a reasonable ICE cogenerator. Compared to SOFC cogenerators, the waste is about 2/3.
not everyone has a new efficient furnace.
I have managed property in Las Vegas for years. They are well maintained properties, however they are now 40 years old. When summer (Vegas's winter) arrives the cost of keeping those apartments (average S.F. 900) rises to almost $400 a month. We have done the simple things like handing out pamplets to turn the temperature up, we have added insulation and changed out a lot of the air conditioners to more efficient units but it gets worse every year. When we ask the owners to consider changing out windows and putting in expensive solar screens most of them simply don't have the money or won't part with the money which is probably the case. They complain about the costs of taxes, property management, maintenance and the cost of a mortgage. All they want to know is when they can raise the rents.
There is no state assistance to help cover the cost of making these units efficient by putting in new windows and doors, solar screens and reinsulating. Most of the owners bought it for a tax dodge and most of them live out of state. They don't see the suffering and they frankly don't give a damn. If someone is 5 days late with the rent they want a 3 day notice to move.
I know of tenants having to make the choice of paying the rent buying food or paying their utility bills or turning off the Air conditioner. If you turn off the A/C it can kill you but I have seen people try and do it. Sometimes I see them sleeping outside on the grass at night (but we are now taking out all of the grass because of the water crises and replacing it with rock).
When people talk about doing all of these wonderful initiatives we need to understand that with the spectre of expensive energy a lot of Americans are about to feel what it's like to be poor. I think our worship of the almighty buck will be a far bigger obstacle to adapting than making strutural changes. Our economy is a model of Reaganomics trickle down.
Consider Las Vegas, "America's ghost capital" if the casinos need anything like an overpass a new plant or siphoning off scarce water resources for Steve Wynn's private 36 hole golf course for high rollors they get it. Poor people recieve little representation or consideration. At the same time the gaming industry pays 6.25% on gaming revenues and any talk of raising that ridiculously low rate is squashed like a bug. The new legitimate face of Las Vegas -International Corporations are far meaner and money grubbing than the mob ever thought of being.
Las Vegas has Little or no social services, and one of the lowest rated education systems in America and has been dubbed "The Misissippi of the West".
The well off in Vegas live behind guard gated communities much like Haiti - so they don't have to see the poor. But Las Vegas is very much like every other city in America - when it comes to taxes even the Democrats are Republicans at heart. If you mention raising a tax even for the most basic necessity it is voted down 99% of the time.
Let's hear comments on how we are going change the way America does business before we start building the infrastructure.
Thanks for noting the perverse incentives at work in situations like rental accomodations. If there's a solution, it's probably going to involve making the landlord (who keeps any capital improvements) responsible for at least part of the energy costs.
If the legislature wants to fix the perverse incentive of taxes, they can exempt the value of efficiency improvements from taxation.
"If there's a solution, it's probably going to involve making the landlord (who keeps any capital improvements) responsible for at least part of the energy costs."
You need to read what I wrote more carefully. What it means is changing tax codes for everyone not merely making the landlords responsible. There is already depreciation on improvements. When you are looking at capitailization rates of 5 to 6% how does it make economic sense in spending a lot of money in capital improvements. That's why they have slum-lords.
What I'm talking about is a profound change in the way our taxation system works. You can call it redistributation or socialism but in a Peak Oil world "business as usual" will only magnify the inequities between rich and poor.
For 95% of the "middle class" population the poor are invisible. People get worked up when they think about some unwed mother getting welfare but nobody bats an eye at the perverse economic system that rewards KBR and Haliburton or thousands of overfed defense contractors that "keep us safe" not to mention ethanol plants in Iowa.
America's current economic system works as long as it is rolling downhill. When the economy changes and the machine has to function going uphill well...I think it's a real good bet that it will sputter and stall!
this has more to do with our over-indebted economy and the collapse of the real estate market than having anything to do with peak oil.
50% of people don't have ANY credit card debt so let's keep things in perspective.
That's good to know John. Maybe we can build debtors prisons for all of those fools who got themselves in over their heads.
As a first order of business for this Brave New World I hereby nominate you for warden.
Any seconds?
The word for the day, and every day, in AmeriKar is squander.
What a tremendous opportunity cost that is associated with driving. Seventy-five percent of the oil consumed daily in the USA is for transportation.
We must take definite step to shift the use of oil resources to more essential needs, such as heating homes and essential business establishments.
We need a leader, maybe Obama?, to alert the American people to raise the problem to the forefront of consideration and propose short and long term solutions.
Don't drive unless you absolutely have to...
Given the right structure, it will be possible to finance them.
California leads the way in innovative financing for conservation.
Basically the energy company installs the equipment, the customer benefits from marginally lower prices for the outset, to incentivise them to have the install carried out, but most of the savings are taken by the company to pay for the equipment.
At the payback the customer then gets the full benefit.
This kind of overall system is very common in Sweden but not as micro systems installed in every house but large often biomass burning combined heat and power plants connected to district heating networks.
Slightly more then 50% of the residential and commercial space heating is via district heating and oil use in these systems has recently become almost abandoned in favor of biomass, garbage, large scale heat pumps, natural gas and some coal. Systems that only burn fuel for heat are quickly being replaced by those that also produce electricity.
In parallell with this we have mass installations of ground source heat pumps mostly replacing oil heating and air source heat pumps mostly complementing houses with resistive electric heating.
Natural gas is in use as residential heat but not to a large degree. There are some companies experimenting with (wood) pellet fired micro combined heat and power and small gas turbines burning natural gas and biogas are commercially available but I have no idea if they sell. Lots of sewage works use biogas for heating and some electricity but most of that will probably be upgraded to wehicle fuel. Biogas and natural gas is too valuble to burn for heat or fairly inefficient electricity production when transportation and (chemical) industry can pay more.
Here is a related post discussing the home heating requirements in USA from natural gas and heating oil by state compared to forest resources. The bottom line is we really use a great deal of oil and gas for winter heating, quantities not displacable by wood on anything but a small scale. I didn't write about scaling up heat pumps but that looks like an important silver BB.
I have a couple of comments. First, natural gas powered heat pumps are already commercially available. http://www.columbiagaspamd.com/products_services/natural_gas_heat_pump.h...
Second, residential cogeneration units are available. George Monbiot highlighted this one in his book "Heat" I think.
http://www.whispertech.co.nz/
Most net metering laws in the US specify renewable power however.
Chris
Many houses and buildings can be heated using solar thermal energy. You can store the heat in the ground during the summer and release it back in the winter. SOFCs can get more than 50% efficiency in generating electricity from natural gas and the rejected heat can be used to heat and cool the building with absorption cooling.
Wouldn't the placing of the heat from the AC side of a GSHP not just dissipate and be lost? It's not insulated from the rest of the ground.
It depends on the kind of soil. It is best to have a perimeter for the heat store. This is a district heating development in Canada that did an insulated store.
http://www.dlsc.ca/borehole.htm
I would think that with further studies done on geothermal systems in homes, the storage efficiency could be quantified. They have been doing geothermal systems for quite a while and data should be available.
It is interesting to note that Whispergen (a domestic stirling electric generator/hot water plant) after spinning its wheels for a few years is now saying they are booked thru to the end of 2009
Whipsergen has always been 'constrained'. When I looked at the +$30,000 diesel units, there was a waiting list. Oh and you had to get 'certified'. The newer $5,000 CHP systems were 'not aviable to mortals' at the time I looked into them.
The core of one of the deployed CHP systems (from my memory - may be wrong) is gone from the web.
From the archive:y
http://web.archive.org/web/20051218114835/www.tamin.com/our_engines.htm
The example from your link is pathetic; a mere 126% AFUE. We should be able to hit 200% without undue difficulty.
The last time I checked the figures from WhisperTech, the number I got for the efficiency of their Stirling cogenerator was 11%. This may do for rich people's yachts, but it will do roughly zip for our energy problems.
A free piston 1kW engine is now being made at about 15/week.
http://www.microchp.nl/stirling_engine.htm
MICRO CHP STIRLING CANDIDATES
Engine-alternator eff. is about 30%, but burner is not too hot (npi).
Important notice in free piston stirlings in March Scientific American. NASA has picked them to replace thermoelectrics, on grounds of much higher efficiency and 15 yr life in space on Pu238.
Free piston lasts and lasts, crank drive stirlings don't. Most people do not make a distinction between the two. BAD mistake. Too bad SciAm made that mistake.
It is a gas company that is distributing these, so a tinfoil hat might fit well. Seems to me though with a 60% efficient combined cycle gas turbine you get to heat four houses rather than three with the same amount of gas even though you discard the waste heat. And, you don't have the noise in a residential area. Noise was also a reason for going with an external Sterling engine for Whispergen I think. Better use of natural gas is definitely a good idea though.
Chris
I Forgot noise. free piston engines don't make any noise thenselves, but their burner/blower might. Crank engines make a lot of noise.
Not 4, 2.67. 50 mmBTU fuel * .6 plant efficiency * 4 heat pump CoP / 45 mmBTU heat required = 2.67. You have the additional burden of transmission and distribution from the remote plants; you don't have this with neighborhood grid-tied cogenerators.
Air conditioners are often noisy, and they operate during the summer when many would prefer to have their windows open. A cogenerating furnace will be much less of an issue.
If we apply a 6% penalty for transmission (7% minus local losses) we get about 2.5:1.
That's not far from the 3:1 gain of the base scenario, and relies on pretty well proven & available heat-pumps, and eliminates the need for establishing procedures for "uploading" power to the grid.
It's a good idea, but it might be good to clarify that most of it's gains are achievable without anything new.
Something to note: the 60% figure quoted for CCGT is usually based on the lower heating value of the natural gas. The feasible efficiency of a domestic gas heating system, cogenerating or otherwise, is well over 90% of the higher heating value, which includes the latent energy of the water vapor in the exhaust.
The lower heating value is 90% of the higher heating value so it we take Nick's 6% T&D loss and apply a lower heating value then we heat 3.4 houses with the turbine as opposed to three with the cogen set up. The main effect seems to be getting better thermal efficiency at scale as you originally noted. The current limit to scale is the turbine. It wins out despite the other effects. On the other side, one want's to look at the efficiency of delivering gas to a residence compared to delivering it to a power plant I think.
Chris
Hi Nick,
Transmission losses account for about 60% and distribution losses about 40% of the 7.2% combined losses in 1995. Since gas plants tend to be smaller and in town connected to the gas pipeline, we should probably count less of the 4.3% transmission loss against them but fully count the 2.9% distribution loss. Your estimate of knocking off a percent is in the right direction though. At 6% loss, we heat 3.67 houses rather than 3 with the same (75 mmBTU) gas use.
Chris
The way I figured it, you were getting enough electricity for two houses at 30% efficient so you ought to get enough for four houses at 60% efficient. I was also comparing your input equally (75 mmBTU, not 50) so that would be 75/50*2.67=4. I did not include transmission and distribution losses. The new gas generator going in here is about 15 miles up the road, but it looks like it is going to be a peaking plant. We did see the new coal plant stopped.
I think it should be possible to make the generator quieter than the heat pumps.
Chris
EP
I assume by efficiency you actually mean electrical generation percentage, since the overall efficiency of the whispergen unit is 90%, This is an interesting paper
Micro Combined Heat & Power
And it outlines some of the difficulties of co-op CHP (not directly) but implies that to much microgen power could be a bad thing, Still engineering a 1kW generator that runs on gas and is quiet enough to sit in your kitchen is a start, Fig 2 shows that only 15% of domestic energy consumption is non-thermal (I assume this is in the UK), So there is little point in changing the ratio (Elect/Heat) as gross export of low voltage back into the network could also cause issues (tho I think they are optimistic on this count as the gas will probably run out)
Neven
Yes, I do. The multiplier effect relies on the electrical generation efficiency, otherwise you might as well be burning fuel in a flame.
"Too much" being enough to make the buildings into net producers, I suppose. This is not a problem if the cogeneration is balanced with heat pumps to maintain the balance. It may be desirable to build in a surplus of generation to charge electric vehicles when other supplies are low; when e.g. wind was good, you'd use that for heat and vehicle charging and back the cogenerator duty cycles off.
One thing I didn't detail above: with a substantial amount of V2G capacity and cogenerators, loss of a line or large generator could be balanced by power from the vehicles for a few seconds, while the cogenerators started and began feeding the grid. Not even ice storms could take out your power.
Which misses the point; by using electricity (work) to run heat pumps to concentrate thermal energy, the total amount of fuel required can be cut in half to start and further offset using e.g. wind energy. By creating efficiencies and substitutions, the pain of declining fuel supplies can be greatly reduced.
EP
Basically you are using the COP of a heat pump as an efficiency increaser, at a 15/85 elec/thermal split in a UK home (based on that document, I'm in NZ) then you could achieve the same effect with a micro CHP/heatpump, ie if you got a 30/70 split and then used the extra 15% to run a heat pump at a COP of 3 then your net energy output would approach 130%, This could be achieved with a beta style stirling engine. You must admit that considering the regulatory and market impediments that whispertech have had to overcome (ie "How do we do this, what! allow a home to generate power, they are a consumer for godsake!" and "Will it work") they have cracked open the door, I think your crack about luxury yachts was disingenuous. ICE based CHP's are noisy, expensive to maintain and would only get a 30/70 split.
Neven MacEwan E.E E&E
The statements made in that cited paper are way out of date. The free piston machines hve high efficiency and very long life as proven by their choice by NASA for long space missions. See current Sci Am. article on space power stirlings.
As the situation continues to decay I'd be surprised if there was not a reversion to coal for residential heating. This could be in the form of coal or coke solid fuel burning furnaces, or Syngas burning equipment. Bad for climate change, but next years winter will trump next generations children I suspect :<
I read some time ago that using an engine to generate your own power requires a relatively large (3+ liter) slow turning (< 1500 rpm) engine for it to have an acceptable lifespan. Our junkyards are full of the right size engines for a fraction of the cost of new engines. Converting these engines to nat gas or propane is not that big of a problem. What is a problem is the supply of alternators of 6 kw+ and the electronic controls if it is going to be connected to the grid. With the projected increase in hybrid and BEV production competition for these devices will be furious. If a system is not connected to the grid auto cruise control from the same junkyards as the engines could be used for voltage and frequency regulation.
I have long wondered if it made economic sense to build a housing development of say 100 buildings with its own cogeneration system. The electronic controls for a 6 150 kw generators is probably cheaper than it is for 100 6 kw units. Why six generators? 4 units provide power, one unit is for backup, and one unit is down for maintance. Diesel engines of this size are regularly manufactured. Sharing of a CHP system of this size opens up the possibility of a central absortion cooler that could use the engines' waste heat for summer cooling.
If you don't want to connect it to the grid, and will use all the work on a heat pump, you need no alternators nor electronic controls. You simply mechanicaly tie the engine to the heat pump.
That even trows away some (very minor, but still existent) waste from converting mechanical work -> eletricity -> mechanical work.
One could also toss on a "wet exhaust" system off a boat to pull the heat out of the exhaust and use in a number of ways.
The advantage to using smaller units, yet diesel, and more of them is the waste heat from the engine could privide hot water in the summer. This especially applies to buildings that contain restaurants, pubs, and other establishments requiring good amounts of hot water.
Thanks for your support:
http://reddit.com/info/6a1lv/comments/ (science)
for those who can't make their mortgage problems all other expenses are tough. oil doesn't have much to do with it when you're paying a mortgage that's 60% of your pay or more. when they go through foreclosure they will rent or buy another home at a price that is a traditional 30% of their pay. then they can easily heat their home.
I have another thought about foreclosure. In my area, many homes are just being abandoned with the former owners getting an apt or moving in with family or friends. If they turn off the heater and freezing weather comes, the house could be destroyed by burst water pipes. I'm in CA now where this won't tend to happen, but used to live in MN, where it could happen easily and in one cold day.
Hi All,
So this story was quite exciting for me. My father is actually the technology director & co/founder of Climate Energy. I emailed him for his thoughts on the article and I thought I would pass along to you his paraphrased thoughts:
The author would probably be happy to know that the free-watt engine generator is really 92% efficient and does condense vapor from the flue gases. We report the lower number only because the cabinet is ventilated, and if this ventilation air is not usable (located in a non-heated space) this heated air would be a loss. Also, if the unit were bigger it would not make any more useful power because it would make more than the home consumes and you don’t get much credit for the excess production in the current system. It would also cost a lot more which is a very real problem.
Thanks for the article, hope that clears up some things a bit.
I was wrong, it's here. it's here! olduvai gorge in America!
Massive Power Outage Reported In South Fla.
http://www.local10.com/news/15415017/detail.html?rss=mia&psp=news
I'm not saying that this isn't a serious problem though. apparently even a nuclear plant lost power but everything is fine.
If we shift from gas heat to electrical heat, even if efficient, we need to consider the adequacy of the electrical supply for the new usage.
My guess is electricity will be a problem sooner than most people are expecting (10 years?). Electrical production will not keep up with need, and grid maintenance will be a problem also. While good planning could better match supply and demand, it seems likely that too little action will be taken. Eventually, planned and unplanned electrical outages will be a frequent occurrence in many parts of the country - similar to what we are starting to see in some of the less developed countries.
For the same reason, inertia and poor planning, gas will likely continue to play a major role in home heating, hopefully a bit more efficiently as EP suggests.
So in practice however much I might advocate it electricity will not take over entirely heating houses any time soon, so that will to some degree mitigate grid problems.
Whatever solutions you come up with though you will need a decent grid.
Solar energy where that is generated at the home may also reduce loads, as it would be generated at the point of use.
In my view however it is unlikely to be a really significant player within the next ten years, although at least for peak load in the south west it could rapidly develop to major importance starting at the back-end of this time-frame.
Other renewables such as massive solar farms or wind power make hugely higher demands on the grid than nuclear, as they would need to transport power far larger distances to where it is needed or to help balance intermittency.
In addition, nuclear power could be used at the low off peak rate to charge electric vehicles, maximising the use of the gird at the least cost.
How would you know when the best time to charge your car from wind power was, as it could maximise at peak, off peak or any other time?
Dave, In the South air source heat pumps can become the norm within 20 years given a little push by electric companies. No added capacity is required. Summer peak capacity plants can be used during winter too. Since almost every home in the South already has central AC, this will mainly be a matter of modifying the AC system, The electrical companies will like it because it would involve year round use of generating capacities once only used in the summer.
If most of the peak load in the South is covered by solar as I expect then that would be an excellent fit to a heat pump, keeping overall system costs down.
Further north tough don't discount air-heat pumps - the latest CO2 ones in Japan are good for down to -15C and one Canadian company does one good for down to -30.
I won't reference them here as they have been extensively referenced in other threads - check out chats I have had here with HereinHalifax.
Everyone in North America will be able to get the benefit of heat pumps without the expense of ground source within a couple of years.
This does nothing to help those of us who either weren't reading those threads, or don't have time to dig the links from them.
No problem - all you had to do was ask- I didn't want to bore anyone if they weren't interested
Here is Japan's horribly named Eco-cute:
http://www.worldofrenewables.com/index.php?do=viewarticle&artid=953&titl...
And here the Canadian offering:
http://www.gotohallowell.com/technical.html
Hallowell International: Technical Data
This pdf might help too, although it is a couple of years old:
http://www.r744.com/knowledge/faq/files/ecocute_all.pdf
Technology and Market Development of CO Heat Pump Water Heaters ...
here is the thread where HereInHalifax makes a number of valuable comments on residential heating:
http://www.theoildrum.com/node/3593
Hope this helps - all this means that for the first time those who live in harsher climates will be able to get the benefits of heat pump technology whilst avoiding the high costs of ground source - pretty transformational, I feel.
And here the Canadian offering:
http://www.gotohallowell.com/technical.html
Hallowell International: Technical Data
Hi Dave,
Just so that we don't panic the fine folks in the great state of Maine, your state has not been annexed by Canada. Rest assured, dear friends, you won't have to add needless vowels to various words, measure your tyre pressure in kiloPascals or end every other sentence with the word "eh?". Oh, special thanks to Bangor, Maine for Stacey's Country Jamboree. We love you, Stacey!
Cheers,
Paul
All the capacity in the world is useless if you have no fuel.
"How would you know when the best time to charge your car from wind power was, as it could maximise at peak, off peak or any other time?"
That's easy. Just use a smart-meter, which receives info about power pricing, together with a charger that communicates with it.
See www.thewattspot.com
Sure, but that is pretty cumbersome as against just plugging your car in overnight when rates are low as you would with nuclear.
If you were at work you might not be able to plug your car in anyway.
" that is pretty cumbersome as against just plugging your car in overnight when rates are low as you would with nuclear."
Well, heck, that's what we can do for the next 10 years for wind, as well. The main problem for wind is the same as for nuclear, that it's output at night isn't needed very much. Charging at night works very nicely for both wind and nuclear. OTOH, time-of-day/smart meters are a good idea in any case, and all US utilities are moving towards them (by federal mandate).
"If you were at work you might not be able to plug your car in anyway."
Again, this is a long-term problem, after we've built a lot of wind (or nuclear). OTOH, it's easy enough to put chargers in parking structures and parking meters. It's done in Canada and Minnesota now, for engine heaters.
In 10 years given the current rate of advances in computer technology, cars will be able to plug themselves in for the night, and unplug themselves in the morning!
Considering it has been in the high 80's and 90's this past week I'm wondering if there was a lot more demand on the grid due to increased AC use. Even though we are used to power outages in these parts usually due to hurricanes, just the chaos that ensues from the traffic accidents caused by traffic light outages at major intersections is a major burden on emergency responders. This blackout I'm sure is no exception. I have never understood why for example,our traffic lights don't have solar powered battery backups for such emergencies?
In the late 1960's and early 1970's my father investigated the health effects of stimulating natural gas production by using nuclear explosions. He concluded that the health effects from radiation would would be minimal, but natural gas could better be used as feed stock for industry. Given a limited supply of natural gas it was more rational to heat with electricity, and save the gas for uses that would add greater economic value to the economy. This is called making wise choices.
Heating in a rational economic world can be handled 2 ways. First through electricity. The second is through renewable energy sources. Biomass approaches are messy and unhealthy. Burning organic material is a good way to create air pollution. I highly recommend that we move away from any fossil fuel source as soon as possible.
Urban wind use is impractical. Most PV's use the grid anyway. Cogeneration still produces CO2. Over time fuel for cogeneration will get more expensive, and will incur carbon penalties as well. Wide spread us of fossil fuel co-generators will contribute to air pollution problems. Even with sophisticated pollution controls, the co-generators will produce fine particulate emissions.
Electricity is more efficiently used with heat pumps, than with resistance heating. Air source heat pumps are now very efficient. Air conditioners are one way heat pumps. It would not be that expensive for air conditioner manufacturers to convert their product line to add heating.
Ground source heat pumps are more efficient, but are much more expensive to install and maintenance problems can be very expensive to solve. Solar water heaters, represent a mature technology, and there are some advantages to electrical utilities to subsidize their installation, with secondary electrical backup.
Solar space heating may have some advantages in the Southwest.
With solar space heating we can save enough natural gas to run our cars. It would require an investment to convert cars to dual fuel and install the solar thermal collectors, geothermal bore holes and heat pumps, but you are trading hardware for efficiency. Running cars on natural gas would be much cleaner and reduce our oil imports.
Yep, I don't think we should be thinking in terms of using natural gas to heat our homes, conservation, insulation, passive heating, nuclear electricity and the new air heat pumps good for down to -15C are the way to go, with natural gas as a transport fuel if we absolutely have to or preferably just a feedstock for industry - it really doesn't make sense to build in a natural gas burn to heat our homes.
It all depends upon your perspective.
Fueling cars with nat gas is easy to do - but a total waste. I commute by bicycle but could easily switch to city bus. If finances get tight the first thing to go is the car - and we would not really miss it. I'd love an EV for in town stuff - and then rent for vacations; but it's not viable - the cost of purchase and insurance is the major cost of a car - NOT FUEL (for us anyway). For the home the major expense is taxes - at >3x the total energy cost of the home.
Ground source heatpumps are neat - but spending $15k for a heating system when it costs $350/yr in nat. gas is kind of insane. High-eff gas furnaces are also electricity hogs. I'd suggest going with a mid efficiency instead and piping it's flue gases thru a HRV. That was discussed back in '91 as you then get the efficiency of a high-eff condensing furnace without the cost of the combustion air motor. In our home the furnace uses around 60% of our total electrical bill. It's rather stunning - but then our normal elec bill is $15 to $20/month (5 kWh/day in the summer and 8kWh/day winter) and the furnace we bought is a York GY9 - AC blower motor - but the DC motor would only save us about $6/yr.
As for passive solar - I wish. My calculations (The Passive Solar House - Kachadorian) gives a peak of about 28% of our total heating from the sun. It's pretty cloudy in southern Ontario and to hit 28% one would have to run around putting styrofoam over the outside or inside of most windows every night! Otherwise TiR Low-E windows would peak at perhaps 20% of total heating needs without having to use thermal shutters.
It's so much easier to do without than it is to chase fancy techo-dreams like ground source heat pumps. I'm keeping my ears open for developments on aerogels though.
most electric cars or PHEVs don't seem to be that much more expensive and as they get widely adopted they will be even less expensive.
"Urban wind use is impractical"
I would not make blanket statements like this. In the upper midwest, where a huge amount of nat. gas is used to heat, the wind tends to blow especially hard in the winter time. Check out the weather in Fargo, North Dakota (240 miles from Minneapolis), and you will see that the wind is nearly always blowing. Really cold days tend to have higher wind speeds. Same is true for many places in Iowa, Nebraska, Kansas and South Dakota.
Wind is practical electrical power for the western part of the midwest. It could easily be supplemented by diesel powered co-generation that runs partly on biofuel and also powered by PV. And as you point out passive/active solar should be a big part of heating.
These guys have a design that could go on top of a lot of big box stores.
http://www.youtube.com/watch?v=Vyvf7iyi-wM
A lot of electricity comes from natural gas turbines, so if you can generate it locally, that is less natural gas used at the power plants.
Here is a study or how wind tracks demand for the UK.
http://www.eci.ox.ac.uk/publications/downloads/sinden05-dtiwindreport.pd...
sinden05-dtiwindreport.pdf
As you can see, it is around two and a half times more powerful in the winter than in midsummer.
Obviously this will vary with the area, but it sounds as though it is good in the area you mention.
That is not so great though if you need air conditioning in the summer, as it won't help much there, assuming it has a similar pattern to the UK.
I also find it difficult to envision a situation where you wouldn't be better off sticking a couple of big turbines really high up outside the city and using that power.
Turbines hate ground effects, like size and height and can cause unwelcome vibration and damage when directly attached to a building.
In locations like London roof turbines are simply vastly expensive eco-bling.
Construction in the northern plains needs a whole new paradigm. We keep recylcing old ideas that are inappropriate for the PPOG world people will be living in.
Obviously, mitigating the effects of the cold winter winds are the first challenge. Combining one or more of the follow ideas should produce much better results than we are now getting.
1) Make sure new construction starts well below grade. To the extent that this can be accomplished, less is exposed to wind.
2)Use "rounded" roof construction that lets wind slip by without producing eddy wake vortices, which cause pressure fluctuations and exchange of air with indoor. A housing "wing" would consist of a dozen or more townhouses covered by a long (upside-down) U-shaped roof, oriented longitudinally to the prevailing winter wind. I think Native Americans used this concept for their "Longhouses". (CMIImW)
3) Construct bike/scooter paths below grade(4 ft.?)and covered with similar rounded roofs. The the excavated dirt could be bermed alongside the path, giving an extra 2 feet of protection.
4) Construct commercial centers (if any are ever built again) with a similar design, additionally having narrow guage rail along the center to ferry people from one end to the other (works for Disneyland!)
5) Build above units for passive heating, to be stored in the summer for winter use (Google Drake, Alberta) or in warm places for maximum reflection of solar radiation.
6) Maximize wind electricity generation, using either horizontal (winter) or vertical (summer) winds.