Throw it back

Honda has announced a cooperative venture with Climate Energy LLC of Massachusettsto produce a "micro-cogenerator" (photo link) based on a Honda engine (hat tips: Green Car Congress via Peak Oil Optimist). The specifics are:

85% overall efficiency.
1 kW electric output.
3 kW heat output.

I make that about 21% electric efficiency and 64% heating efficiency [1].
Poster Gene DeJoannis at the GCC discussion notes that 3 kW of heat is only about 10 kBTU/hr, which is not enough to supply the peak winter heating requirements of a small row house, let alone a single-family home. It follows from this that the cogenerator is not capable of functioning as a stand-alone heating system; it would require extra heat. The concept is that the engine runs continuously, and heat requirements beyond the CHP system are provided by a conventional combustion boiler. This is included in the auxiliary furnace. (These graphics answer some questions regarding the odd-looking cogenerator efficiency numbers; it appears that the cogen exhaust does not allow recovery of the latent heat of the water vapor and is also a separate unit from the air handler; as a consequence, heat losses are higher from the cogenerator side than the backup furnace.) It also appears that the full heat demand of a house can be met by the pair, and that the $8000 cost of the two units covers the entire heating plant. Earlier, I had objected that a $8000 capital expense is very hard to pay off with a $600/year revenue stream; it appears that the incremental cost of the cogenerator over a conventional furnace is considerably smaller, and the payoff quicker.
The stated purpose of this cogen is to meet the average electrical demand of the typical house, without generating surplus power to feed the grid. I believe that this is a mistake:

This choice requires the utility to handle the difference between base-load and peak requirements. It would be trivial to trade off heating duties between a bigger cogenerator and the furnace section to approximate the daily demand curve and smooth the load at the utility. Instead, the cost of winter peaking is put where it's the most expensive (and least efficient) to meet it.
The design removes most capability of generation for backup power.
The design foregoes the capability of generation for other loads, such as charging electric cars. In other words, it's not designed with the future in mind.

IMHO, a properly-designed system would be able to handle contingencies. If the generator was capable of 3 kW and 30,000 BTU/hr, it could supply a 1 kW average electric load by operating at a 1/3 duty cycle. It would also be able to crank up to full output and 30,000 BTU/hr to handle cold snaps, and help to feed the heat pump of the house down the block. When the homeowner came home with a Prius+ or the like, the system could be programmed (perhaps via a Bluetooth or WiFi connection) to react to the car plugging in and boost generation to charge it on power from natural gas instead of oil.
But this isn't going to happen, because it's just too small. The designers thought too small.
This one looks like it's under the limit. It needs to grow some; throw it back.
[1] The low efficiency is a disappointment too. Cummins claims BSFC as low as 0.32 lbm/hp-hr for some of their diesels; assuming #2 diesel at 19,110 BTU/lbm this works out to over 41% thermal efficiency (and that's the higher heating value to boot). It ought to be possible to achieve much better than 21% efficiency from a gas-fired reciprocating engine; perhaps this requires the freedom to begin with a clean sheet of paper. ¶ 4/30/2005 12:08:00 AM 8 comments

Friday, April 29, 2005

It's all gas

I listened to Bush's press conference last night with a growing sense of frustration and irritation. Does the man know nothing? Is he unable to see how his own policies have accelerated us to the crisis we now face? Or is he just a sociopath like Clinton, able to say whatever serves his immediate purpose with all apparent sincerity? Regardless, what he said wasn't right; to the extent that it wasn't irrelevant, it was some of the worst political posturing I've listened to since Clinton's talk about firearms and interns.
One comment that really got to me was Bush's anecdote of the soldier who asked him to lower the price of gasoline. Bush's response was that this was beyond his abilities. Well, of course it is... now. But was it always? Had I been there and able to interrupt, I would have had to ask "Mr. President, the high price of gasoline is due to high world demand for oil and an excess of gasoline demand over refining capacity in the USA. We used to have programs to do something about that. But didn't you cancel the Partnership for a New Generation of Vehicles, and didn't you sign tax breaks which encouraged people to buy gas-guzzling trucks for business use whether they needed them or not?"
Among Bush's first acts in office, he cancelled a program which was ready to produce highly economical vehicles in the very near term; he substituted a hydrogen-vehicle program which is still unlikely to yield products before 2015 and will require tens or hundreds of billions in new infrastructure to support. The first-year tax writeoff for vehicles over 6500 pounds used in a business helped to run up gasoline demand, creating windfall profits for gasoline refiners. He also funneled a bunch of research money to the auto companies for the long term.
Was it worth it? Here's what we lost:

Valuable capacity margins in fuel refining.
A better situation with regard to foreign exchange.
An American hybrid program which would have been market-ready by now.
Domestic vehicles ready to be converted to Calcar-like plug-in hybrids.
A ready response to high world oil prices.
Product lines at domestic manufacturers ready for the shift in consumer demand.

We should be so much further along than we are. PNGV vehicles like the Daimler-Chrysler ESX3 were delivering 72 MPG back in 2000. The diesel engines might not have met new EPA NOx standards, but so what? Even if they had to be powered with gasoline engines and some of the more expensive technologies had to be left off, it is hard to see how the ESX3 and its like could have achieved less than 50 MPG. With the addition of removable battery packs, such cars could have operated entirely on grid power for short trips while maintaining their cargo capacity and highway fuel economy; experiments with the Toyota Prius have shown that this can be done by dedicated amateurs. But they've got to buy Japanese cars to do it, because Bush decided that his predecessor's program wasn't politic.
Bush's idea of an energy policy seems to be to:

Meet with the Saudi oil minister and ask him to pump more oil;
Hand out lots of subsidies and tax breaks to existing producers;
Throw money at farmers and ADM (but producing little new energy) through ethanol[1] and biodiesel subsidies.

None of these initiatives affects anything where the rubber meets the road. None of them are going to do anything for the budget deficit or our balance of trade. Arguably, none of them are going to improve our situation; they are just going to create financial empires based on government largesse.
Bush ought to have expertise in the oil business. He ought to have seen all of this coming; he certainly knew the right people to ask for advice (and if he didn't, Cheney did). He should have known what programs should have been kept on the back burner for the sake of the nation and our domestic industries. He was only too happy to use largesse (e.g. tariff barriers on steel) to buy votes, but he could have made it go much farther with some statesmanlike vision.
We didn't get it. What we got instead appears to be programs designed for the benefit of a favored investor/CEO class and the very foreign oil interests who are waging religious war against us.
This isn't leadership. Neither is it patriotism. And when the American people figure this out (probably about the time the Democrats break with the forces of P.C. and get serious about national security), there's going to be some mighty big scores settled in Washington.
Either that, or the USA becomes one more banana republic.
[1] Ethanol from corn appears to be a loss, energy-wise. A recent paper claims that it's bad for just about everything it touches. Corn (maize) is planted, cultivated, sprayed and harvested with petroleum products, fertilized with nitrogen fixed using natural gas, and the ethanol product is distilled using more natural gas or petroleum-derived propane. This does nothing for our security; due to the cost of natural gas, even our nitrogen fertilizer is now imported. The only purpose served by these subsidies is to transfer taxpayer dollars to the pockets of those chemical producers and agribusiness interests like ADM, with a little trickling down to the farmers almost by accident. If Bush wanted to cut the price of gasoline, he could push to eliminate the use of ethanol in gasoline and pay farmers to idle some of their acreage instead; all the fuel the farmers are using on that idled land would make motorists happier. And that could be done in time for this year. ¶ 4/29/2005 04:09:00 PM 8 comments

Thursday, April 28, 2005

It's (a) mine!

I've been reluctant to talk much about nuclear power here at The Ergosphere because it's such a politically-charged topic. The various issues of fuel availability, waste disposal and vulnerability of reactors to attack attract a great deal of argument with little agreement even on premises, let alone conclusions. This makes it a singularly unfruitful area for discussion; it generates a lot of heat but precious little light.
It might be more fruitful if some of the issues could be taken off the table. Two of these issues are vulnerability of reactors to terrorist attack and likelihood of leaks from other accidents. Reactors are large, stationary (albeit fairly hard) targets; if the same countermeasures could essentially eliminate the ability of terrorists to hit the reactor while also confining most conceivable radioactive accidents to the immediate area, both the real and perceived risks of nuclear power would be greatly reduced.
One speculative vulnerability of reactors is aerial or artillery attack, to breach the containment building and rupture the reactor vessel to cause a meltdown. Leaving aside the extreme difficulty of getting several bombers or a howitzer into the country and to the proper position for attack, it's obvious that neither of these attacks are even possible unless the reactor is above ground. An underground installation is completely immune from attack by artillery and would require nuclear bombs to damage with an aerial attack; a terrorist attacker with a nuke has much better and softer targets than reactors. It appears that underground construction (at an adequate depth) is sufficient to eliminate most direct modes of terrorist attack.
The main issue with any such thing is the cost. Mining costs money, construction in confined spaces is more difficult and expensive than in open air, and engineering has to be done differently (and thus separately) for structures intended to go underground. This would make underground nuclear installations more expensive to build than aboveground ones. But, I ask, are there compensatory benefits?
I can think of a few:

There should be few issues with off-site liability insurance.
Decommissioning means removing the fuel and locking the doors (well, pouring concrete in the tunnels).
As isolation is achieved with a physical barrier rather than distance, plants can be located close to the points of use.
1. Transmission losses are reduced.
2. Plant waste heat can be used productively.

That last is the big one. If the typical plant is a pebble-bed HTGR with a conversion efficiency of 40%, it increases the useful energy from the plant by 150%.
District heating was once commonplace in cities, and the heat came from the low-pressure steam output of generation plants (this is still in use in some places, including many university campuses). Unfortunately, the effort to remove pollution sources from cities also caused all the byproduct heat to have to be dumped as waste, as heat cannot be transported long distances without unacceptable cost and losses. There is now an opportunity to reverse this trend and capture that waste energy. But what's the value, and is it enough to pay the extra costs?
Assume for the moment that the new reactors are 400 megawatt pebble-bed HTGR's, the thermal efficiency is 40%, and T&D losses for the typical above-ground unit are the average 7%. Further asssume that the T&D losses for the underground unit are 3%, and heat losses are 10%. The net product looks like this:

Unit	Output	Deliverable fraction	Net to user
Remote aboveground	400 MWe	0.93	372 MW
Remote aboveground	600 MWth	0	0
Local underground	400 MWe	0.97	388 MW
Local underground	600 MWth	0.90	540 MW

The ability to deliver "waste" heat in this case more than doubles the total usable output from the plant. But the question still has not been answered: what's the value of this new product?

The big answer depends on a bunch of smaller questions:

How much of the rated heat output of the plant is used?
What energy source is it replacing?
In what form is it delivered?
What is the cost of delivery?
What is the backup in case of interruption?

For the sake of discussion I'll propose numbers that are not researched and I hope aren't too unrealistic:

Customers use 60 percent of rated output heat (the plant may produce less than full output at times of low demand).
This replaces natural gas for space heat and DHW, as well as electricity for air conditioning (via absorption chillers).
Heat is delivered as hot water or low-pressure steam at ~100 C.
For a wild-assed guess, cost of delivery is 1 cent/kWh.
The backup is electric resistance heat (used to supply service when steam/water delivery is interrupted). Note that this is better than current gas service, which provides no backup.

The retail price of natural gas is unlikely to go below $7/million BTU in the next few years; if used at 95% efficiency, this corresponds to a price of 2.5 cents/kWh of heat. The net value of the heat delivered is the difference between this and the delivery cost, or 1.5 cents/kWh. For absorption A/C the energy replaced is electricity rather than heat. The real cost of on-peak electricity for A/C is at least 15 cents/kWh and sometimes much higher, so for this example I will assume a flat 20 cent rate. The coefficient of performance (CoP) of a good vapor-compression air conditioner is around 4, and the CoP of an ammonia-water absorption-cycle chiller is approximately 0.5; it takes about 8 kWh of heat to displace 1 kWh of electricity for cooling, so the displaced cost of heat used for cooling is about 2.5 cents/kWh of heat (again).

Output	Deliverable fraction	Capacity used	Net to user, average	Delivery cost	Cost displaced	Net value per unit	Units per year	Net value delivered
600 MWth	0.90	0.4 (heating)	216 MW	$.01/kWh	$0.025/kWh	$0.015/kWh	1.892*10⁹ kWh	$28.4 million
600 MWth	0.90	0.2 (cooling)	108 MW	$.01/kWh	$0.025/kWh	$0.015/kWh	9.406*10⁸ kWh	$14.2 million

The total net value delivered is $42.6 million/year, or $106.50 per kilowatt of electric capacity per year.

If natural gas goes up to $10/million BTU, the cost of heat from gas goes up to 3.6 cents/kWh and the situation looks even better:

Output	Deliverable fraction	Capacity used	Net to user, average	Delivery cost	Cost displaced	Net value per unit	Units per year	Net value delivered
600 MWth	0.90	0.4 (heating)	216 MW	$.01/kWh	$0.036/kWh	$0.026/kWh	1.892*10⁹ kWh	$68.0 million
600 MWth	0.90	0.2 (cooling)	108 MW	$.01/kWh	$0.025/kWh	$0.015/kWh	9.406*10⁸ kWh	$14.2 million

The total net value delivered nearly doubles to $82.2 million/year, or $205.50/kWe/year.

What kind of investment does this justify?

I'm no financial expert, but interest rates are fairly low at the moment. If the investment in heat delivery infrastructure is financed at 6% and amortized over 30 years, the heat stream is worth about $1470/kWe at the $7/mmBTU cost of gas and a whopping $2830/kWe at the $10/mmBTU price of gas! In contrast, the cost of mass-produced pebble-bed reactors is estimated at $1000/kWe. It appears that the ability to make use of plant waste heat is worth doubling or even tripling the cost of construction.

What would it look like?

From the surface, not much; probably an access tunnel from a building in an industrial or office park. During construction there would be a lot of trucks taking soil and rock away and delivering concrete and other materials. Cables would come to the surface in one or more places to transmit power to electrical substations.

Underground it would be more interesting. The reactor proper would lie at a safe (and perhaps considerable) depth, and its main power turbines would be sited with it. But the heat distribution network would radiate outward from it like a starburst, with pipes carrying medium-pressure steam upward to local pressure-drop recovery turbines in neighborhood manholes feeding the local steam/hot water distribution pipes. Instead of a gas pipe coming into the house, there would be a steam/HW supply pipe and a return pipe.

One curious feature is that the heat-distribution system would require no pumps. Water coming down from the surface would arrive at a depth of 1000 feet under more than 400 psi of pressure from gravity alone; this pressure would have to be relieved through a throttling valve or turbine to reduce it enough for the water to boil at less than oven temperatures. Low-pressure steam has very low density, which requires pipes too big to run long distances; the distribution network would probably use steam at a moderate temperature and pressure. Medium-pressure steam is far less dense than water, and would arrive at the surface at not much less pressure than it left the underground; the pressure could be used to drive another turbine. This convective loop could generate power and provide fail-proof circulation.

Hardware at buildings would change too. Instead of a furnace, you'd have a fan coil heated by steam or hot water; instead of a boiler, you'd have a simple heat exhanger (with backup resistance element). The water heater would look like an electric, but with a water/steam coil in the bottom. But the big difference would be in air condtioning systems. Absorption systems would be larger than compressors, and would need to reject almost 3 times as much heat; the outdoor units would be quite a bit larger than present compressors. It might be worth putting them partially underground, leaving only the condenser coils in the air. It might also be worth installing the condensers in thermal chimneys, to cool them with convective airflow and eliminate the need for fans. This would have a definite and distinctive architectural impact.

Given such a heat distribution network, the reactor would not need conventional cooling towers. The A/C chimney systems could be employed as heat dumps when supply ran beyond demand.

Risk factors

Depending on the reactor design, the potential for damage or failure seems very small.

Pebble-bed reactors cannot melt down.
Deeply buried reactors cannot be hit by aircraft, bombs or artillery.
Gas-cooled reactors are unlikely to transfer radioactive materials to cooling water or steam.
Physical isolation of the reactor reduces or eliminates most other hazards.

Worth doing? Depends what it costs to build something in a mine, dig miles of tunnels and lay new piping networks. But if it is, entire cities could be made independent of oil, coal and natural gas for all their heating, cooling and electric requirements and do it cleanly and quietly.

That's my kind of solution. ¶ 4/28/2005 06:06:00 PM 6 comments

Sunday, April 10, 2005

How to be pathetic

Reps. Fred Upton (R-MI) and Ed Markey (D-MA) have co-sponsored a measure to extend Daylight Saving Time by 2 months (hat tip: Enviropundit). The alleged benefit is a savings of 10,000 barrels of oil per day.
US oil consumption is about 20 million barrels per day. The alleged benefits amount to one twentieth of one percent. Why are they wasting their time and issuing press releases on what amounts to Trivial Pursuit? Is this what their constitutents sent them to Washington for? Have they nothing better to do?
Those two should withdraw their bill and start over. If they wanted to make a real difference, their bill should require that, by 2010, 50% of all passenger cars and light trucks sold in the USA must be able to travel 20 miles at 55 MPH on electricity alone, no liquid fuel allowed (the Prius Plus program has shown how easy this is to do). This bill should also immediately return depreciation schedules for all business vehicles to normal at the same time... retroactively for all the doctors, lawyers and other people who bought huge trucks as status symbols instead of business necessities. That would do something about our budget deficit too. ¶ 4/10/2005 10:37:00 PM 4 comments

Wednesday, April 06, 2005

What side are they on?

Everybody has biases. The Republicans have biases. The Democrats have biases. Oil and coal company executives are biased. Environmentalists are biased. The P.C. contingent [spit] on the campus of my alma mater will deny they are biased because "multi-culturalists make no judgements and cannot be biased", but that in itself is a bias against the values of the majority society.
I'm biased. There, that's out of the way.
There are differences between biases. One can have biases which are based on (ranked from noble to ignoble) honest disagreement about the meaning of the facts, ignorance, or disregard for the facts. The biases one carries are part and parcel of where one stands in the various conflicts in life: which side you're on.
Biases can be overt. I hope I've been honest if not completely explicit about my biases against pollution, economic foolishness like perverse incentives and counterproductive subsidies, dependence on foreign oil and our gas-pump financing of radical Islam, and for efficiency, nuclear power, alternative energy where appropriate, and better ways of doing things in general. If you've missed this before, here it is; if you see me appearing to argue contrary to one of my positions above it's almost certainly because the devil is in the details and it's often very easy to miss one little thing and get the big thing badly wrong. (See CAFE regulations.)
Hidden biases are another thing. They are one of the trademarks of propaganda, and are often used to mislead. They come in a dozen styles, but one is to gloss over or ignore facts which would lead others away from the propagandist's desired conclusion. The desired conclusion may be one to compel action where none is desirable or warranted; contrarily, the desired conclusion may be that action is futile, inducing paralysis in the believers when something can and ought to be done.
Which brings me to the most recent newsletter of the Association for the Study of Peak Oil&Gas ("Life after oil", article #524, pp. 7-9). This piece, excerpted by C.J. Campbell, appears to be largely taken from a 2003 book by William Stanton; it paints a future of England in 2050 which is powered by biomass in the form of wood. According to the author, the maintenance of a "passable standard of living" would require about 230 tons of wood per person per year. The resulting economic and social organization would yield a lifestyle which is "attractive for the survivors".
Survivors, you say? Yes, survivors. How many survivors? About 2 million: one-third of England's population in 1750, and one thirtieth of the population today. Consider this carefully: if one quarter of England's current population is now under the age of 20, eighty-seven percent of those people will have to be gone before the age of 65 for the population to drop to 2 million. The alternatives: leave the country (for where?) or die. And there could be no births in the whole country for the next forty-five years, because for each baby somebody else would have to go.
The transition to a peaceful, stable and sustainable society would have to be done carefully. A smooth evolution is essential; serious instability would destroy many of the resources that the future economy would depend on. Does anyone in their right mind think that eighty-seven percent of the population is going to accept deportation or early demise quietly? Can anyone believe that the kind of crisis (like a plague) which could do this without explicit violence would leave much behind? Yet this kind of mess is left, implied but unstated, in the text.
What conclusion is the reader supposed to draw? How about "Oh my god, sustainable society is just code for MASS DEATH! We can't even think of going down that path!" Or, "We can't live through the changes coming. Eat, drink and be merry, for tomorrow we die." In other words, action is futile. The product: paralysis. Might as well go along with the status quo... enriching the current crop of oil barons. They can't take it with them either, so it doesn't matter. Does it?
Well, yes. It does.
To avoid paralysis, it's essential to notice that the conclusion is only valid given the premises. Minor premises are that there are no low-energy or renewable substitutes for steel and concrete, but the key premise in this case is that biomass (in the form of wood) is the best sustainable power source for a post-fossil society.
I'm going to take Stanton's key premise and examine it. Is 230 tons of wood per capita per year a reasonable assumption, what would it take to get its energy equivalent without burning fossil fuel, and how much land would be required?
Assuming elm wood at 20 million BTU/cord (128 cubic feet), 23% void space and 35 pounds per cubic foot yields a heat product of ~5800 BTU per pound or ~3750 kWh per metric ton. 230 tons per capita per year comes out to 862,500 kWh/capita/year or an energy consumption of 98 kW equivalent. That's average, not peak. This is clearly a very high number, leading to an extremely pessimistic conclusion.
Is it warranted? The average household in the US uses about 1 kW average, and industrial and commercial uses are only a few times that. Net consumption of energy by cars and trucks is about 1/5 of total electric generation capacity. It seems reasonable to set the actual per-capita energy needs of a decent society, not particularly optimized for efficiency, at 10 kW or less. Boom, the sustainable population of a wood-burning England rises to something closer to 20 million. You'd have to stop immigration yesterday, make sure the NHS doesn't keep old people alive too long and get birth control to everyone, but none of the under-20's have to go anywhere. They can even have a few kids.
But is the assumption of a wood-burning England reasonable, even remotely? I don't believe so. Forests are not particularly good converters of solar energy to biomass; they use a great deal on housekeeping. Grasses are certainly better. But is biomass even among the top contenders? Stanton's productivity figure of 8 dry tons per hectare per year leads to an average power capture of 30,000 kWh/ha/yr or 3.4 kW/ha. This is a pitifully low figure. If the average house has a footprint of 80 square meters, the roof is covered with PV cells at 15% efficiency and each square meter receives an average of 4 kWh of sunlight per day, the roof would produce 48 kWh/day or an average of 2 kW. A hectare of these roofs would average 250 kW, or more than 70 times Stanton's assumption. A city-full of solar roofs could easily be twenty times as productive as Stanton's proposed energy farms; a hectare could support the complete energy needs of 25 people, and the land Stanton would devote to a hamlet of 100 would be able to support the energy needs of 7500 people using a mere 10% of its 3000 hectares - much of which could be met by the light falling on buildings and roads. (Boom, the sustainable energy production could support 150 million; food, fiber, materials and crowding would come into play first.) It is clear that the assumption of a wood economy is not just unreasonable, it is ridiculous.
Stanton looks at materials as a difficulty; steel and concrete are big energy-hogs. Well, maybe. If iron oxide is available it can be reduced using carbon monoxide, which can be made from most anything carbonaceous; a net consumption of 50 kg/person/year could be satisfied with roughly the same weight of wood. A population of 50 million would consume 2.5 million tons, using the wood grown on 312,000 hectares of tree farms. (Electric reduction of iron salts to metal would slash this number immensely.) And steel is not necessarily an essential material; composites made of carbon or organic fibers (graphite or Kevlar) in organic (epoxy) binders can replace it for many purposes, including the wind-turbine blades and towers that Stanton is so certain are non-renewable.
Building materials? Consider structural insulated panels. A house made of SIP's with 6 inch (~15 cm) foam cores and 5/16 inch (.8 cm) plywood or OSB skins would use about 11 kg of material per square meter of wall; a comfy 2 story 200 m^2 house might use about 700 m^2 of panels including floors (but no interior walls), or about 7.7 tons of wood and foam. If all of that material comes from tree farms, that's about 1 house per hectare per year; if one person uses 1/80 of a house per year, the housing needs of 50 million people could be met from 625,000 ha of tree farms. Between steel production and housing, tree farming would need roughly 1 million ha out of a total area that Stanton appears to count as 60 million hectares.
Is there cause for such pessimism as Stanton's? I see a renewable future just as populous as the present, and a whole lot more technological and dynamic than he seems to. The road there need not and should not involve any die-offs (warfare against dysfunctional societies bent on the conquest or destruction of the rest of the world being a possible exception). It just requires the application of good science and a lot of cleverness.
Science and cleverness that Stanton and his fellow travellers paint as futile, and thus not worth the effort.
Which makes their scenario a self-fulfilling prophecy.
What side are they on, anyway? ¶ 4/06/2005 06:18:00 PM 22 comments