<DrumBeat: February 28, 2007 The Oil Drum DrumBeat: March 1, 2007>

202 comments on That cubic mile

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goinggreen on February 28, 2007 - 12:28pm Permalink | Subthread | Comments top

Great post EP. I gotta call you on the Nuclear numbers, though. How do you deliver the low-grade heat to homes that currently use heating oil, etc? There is also the transmission loss, and then the loss in the presumed charging of the electric vehicles that would be required in an electric-only world. A quick guess would be that you'd need about double your 14 1.1GW plants/year. Still under the 52/year from IEEE.

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Not ManCon on February 28, 2007 - 2:57pm Permalink | Subthread | Parent | Comments top

How do you deliver the low-grade heat to homes that currently use heating oil?

Do what was done in London with Battersea Power Station - simply have big pipes conducting the hot water to the houses across the river. It was then like a giant central heating system.

(From the book London Under London):

When the power station was functioning, it carried untreated Thames water, heated to boiling point in the power station, under the River to Dolphin Square and the Churchill Gardens Estate, supplying the flats with central heating before discharging the water back into the Thames.

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goinggreen on February 28, 2007 - 7:02pm Permalink | Subthread | Parent | Comments top

Should we put our Nukes in the city centers? What is the chance of getting that done?

I'm all for harvesting the wasted heat. For instance, check out the Ecopower combined heat/power unit (goggle it, it is pretty good). That takes care of the 60%+ energy loss due to heat/transmission. Unfortunately, it runs on fossil fuels, though a hydrogen version should be possible. Still, it is no Mr Fusion, but then I'm not holding my breath for that one.

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memmel on February 28, 2007 - 10:38pm Permalink | Subthread | Parent | Comments top

I initially read that is should we Nuke our city centers.

I thought it was a pretty good idea.

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Davidyson on March 1, 2007 - 5:21am Permalink | Subthread | Parent | Comments top

In fact, it's called combined heat and power (CHP) with district heating.

This is something widely used in Europe (especially Denmark and Germany). 30% of Berlin's (ca. 3.5 million people) space heating requirements are covered by CHP.

So, it's absolutely no rocket science and has been refined and optimized for decades already. Just not in the UK or the US.

CHP causes slightly lower electric conversion efficiency (like, 5% less), but makes use of this 5% loss to deliver another like 20%-30% of the otherwise wasted primary energy to the homes.

CHP with nuclear plants is not exactly a good idea. Consider a radioactive leak in the plant, contaminating the hot water loop. It would have to shut down immediately to avoid pumping radioactivity into the homes, leaving entire cities cold from one minute to the next.

Micro-CHP units in individual homes are half-nonsense, because
- the capital cost for a home owner to buy such a thing is much higher than for large-scale utility companies,
- maintenance needs to be organised in much more decentralized and therefore more inefficient way,
- a change of fuel is almost impossible and
- propagation of such units is much slower than with a central solution which would serve whole cities or at least city quarters in one go.

Cheers,

Davidyson

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goinggreen on March 1, 2007 - 5:09pm Permalink | Subthread | Parent | Comments top

Micro-CHP units in individual homes are half-nonsense, because...

Have to disagree here in USA circumstances. With most homes heated by natural gas (at least presently), the CHP unit does not necessarily mean more maintenance than present if current furnaces/boilers are swapped out with CHP. It also gives the homeowner electric power that is competitive with utility-based power (due to addition of taxes, etc), and also gives backup power during (the rare) outages.

Here in Connecticut, with some of the highest rates in the country (Long Island and Hawaii are the only higher areas), the CHP unit I'm installing will pay for itself in under 8 years. It helps that we have net-metering. If we could get hourly net-metering, the unit would pay for itself in probably 5 years or less.

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Davidyson on March 2, 2007 - 4:52am Permalink | Subthread | Parent | Comments top

Hi goinggreen,

thanks for the reply.

You are right - there are of course places and circumstances in which micro-CHP actually makes sense.

However, please note that what might make sense for you as an individual might not make sense for society. The capital cost point remains, as does the fuel switching point and the speed of propagation point.

Also, micro-CHP units are more complicated than simple gas boilers, so probably subject to more or more expensive maintenance.

Cheers,

Davidyson

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Engineer-Poet on March 1, 2007 - 1:31am Permalink | Subthread | Parent | Comments top

As for the comparisons, I plead haste.  (I noticed, too late, that I hadn't dealt with the amount of heat we get from natural gas and coal, directly and indirectly.  That would have to figure somewhere, and I intend to go back and insert a note to that effect.)

Delivering heat to homes isn't necessarily impractical.  If you are willing to put a nuclear plant in tunnels beneath a city (and what better place to put it to eliminate the threat of terrorist attacks?), you could transfer the heat as medium-pressure steam to neighborhood energy recovery turbines [1] and then the exhaust low-pressure steam or hot water for space heat.  The water goes back down to the steam generators by gravity. [2]  I did a writeup on this almost two years ago.

When heat is not required for space heat or to drive absorption A/C, it could be vented through cooling towers.  These might be integrated with office towers or other buildings.

Electric transmission losses, battery losses etc. would probably be on the order of the efficiency gains from electric drivetrains.  This looks close to a wash.

The one thing I didn't consider is higher-grade heat requirements for e.g. industrial process heat.  This could also be supplied by nuclear (which was the original intent of what became the Midland Cogeneration Venture in Midland, MI) but there would be a greater impact on electric output.

[1] Medium-pressure steam is probably better than low-pressure, because the pipes will be much smaller, cheaper and have lower heat losses.

[2] If the reactor is deep enough, gravity could provide a large part of the pressure required for the boiler feedwater.

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AlanfromBigEasy on March 1, 2007 - 8:21am Permalink | Subthread | Parent | Comments top

Electric transmission losses, battery losses etc. would probably be on the order of the efficiency gains from electric drivetrains

And if the batteries are replaced with an overhead wire ?

No battery cycle losses (out/in), no weight to haul around (include structure to support the Battery), no wasted time and distance refueling.

Best Hopes,

Alan

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202 comments on That cubic mile

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