OT: Following on from Windmill/nuclear discussion

[Fitz]

Related to that discussion but I couldn't find a suitable 'jump off' point.

I don't want to sound like an IMM level fantasist, but I seem to remember reading something somewhere about ethanol powered fuel cells. The article was suggesting that algae could be grown in conditions which caused it to produce ethanol which could then power a fuel cell.

How feasible would it be to have locally generated electricity from industrial sized fuel cells powered by ethanol generated from a renewable source like algae?

I suspect the main problem is in the surface area needed to generate the quantity of ethanol required for serious production of electricity. I'm sure someone else can point out far more obvious flaws.

Also how much does local generation lower the overall generating capacity required because it doesn't have to be pushed so far over high voltage lines? Having said that I'm making the huge assumption that pushing electricity over high voltage lines is wasteful... which as assumptions go I couldn't actually justify...

Anyway - just wondering. Not trying to start another barney

[Brian Sharrock]

The first 'obvious flaw' that springs to mind is the adage;- "There's owt for nowt" Energy and/or matter can't be created from nothing. So, what provides the energy to grow the algae ... ? If it's sunlight - couldn't a solar collector heating water be more effective?

[Mary Fisher]

I've never heard that, do you mean, "You don't get owt for nowt?

Good point!

Mary

[meow2222]

same reason most possibilities dont get used, cost.

NT

[The Natural Philosopher]

About as inefficient as sticking it in a car engine, but yes, why not?

Why not simply grow sugar beet, boil it, ferment it and distill it and use it to run your central heating on?

Very little.

Everything is possible and cost benefit analysis needs to be rigorously applied to determine what energy policy is actually cost effective.

'What we did yesterday' is always cheap because its been done already, and its always predictable capital cost and depreciation wise.

The trouble with 'new technology' is that its new..no one really knows how much its going to cost, and whether the long term payback will make it a winner, not viable at all, or somewhere in between.

Only when you have a really STUNNING case on paper - as nuclear power was in the 50's - will people stump up the bucks.

OR when its really DIY stuff, like black painted radiators on the roof to warm the water.

[The Natural Philosopher]

Surprisingly enough, organic plant life and photosynthesis as a lot better at making energy than any 'industrial' solution.

Photpxcless are a perecnt or sop efficient, at best, and they like bright sunlight.

Best power is solar furnace..curved mirrors in desert pointing sun at boilers..

In more temperate climes, growing and harvesting stuff is as good as it gets.

[nightjar]

Losses in 2003/2004 varied from 4.4% to 9.3%. Excluding distribution losses from the Scottish hydroelectric plants, which tend to be a long way away from where the electricity is used, the range is 4.4% to 7.1%.

Probably the most practical form of distributed generation is domestic combined heat and power. That involves sticking a Stirling cycle generator in a domestic boiler, which produces about 1Kw of electricity for every 8kW of heat. The big advantage is that it produces most electricity in the coldest periods, which is when it is needed most.

Colin Bignell

[David Hansen]

On Fri, 14 Jul 2006 01:24:44 +0100 someone who may be "nightjar" wrote this:-

Not quite. Many of the more rural parts of Scotland used to have island supplies, for example Morar fed the Mallaig area and Nostie Bridge fed Kyle of Lochalsh. Over the years these island systems were linked up to provide more reliability and more maintenance opportunities. That does mean there are longer distances at times.

The southern group of hydro stations above the Forth-Clyde line are reasonably close to Glasgow, Stirling, Perth and Dundee, but the northern group are more remote, though Inverness and a few other places are close. Those stations south of the line are largely rural stations powering mostly their local area but connected to the rest of the system, much like the north west.

[google]

What powers the domestic boiler? The whole point of the excercise is to _reduce_ reliance on imported natural gas, not make everyone even more dependant upon a single fuel type, which seems pretty stupid IMHO.

MBQ

[The Natural Philosopher]

A domestic boiler will either be optimised for gas, or kerosene/diesel.

You can grow biodiesel.

But reducing the amount used is as good as replacing it with something - like coal - that is locally available, yet still adds net CO2.

[nightjar]

A Stirling cycle engine does not really care what you use to supply heat to it. It is simply a way to utilise waste heat and the boiler can run on any fuel you want.

Colin Bignell

[David Hansen]

On 14 Jul 2006 03:07:11 -0700 someone who may be [e-mail] wrote this:-

Which it does. By producing heat and electricity one is making the best use of gas and thus reducing reliance on it.

The current "bright" idea form party politicians and officials is to burn gas in the home to produce heat but no electricity and to burn gas in a power station to produce electricity but no heat (for homes). That is pretty stupid.

[Mark]

What is the advantage of one of these CHP boilers over a good condensing boiler in terms of overall efficiency? If it really produces 1kW of electrical power to 8kW of heat I would guess that the boiler itself is non-condensing. Or is it really close to 100% efficiency in terms of electricity and heat production?

Mark

[The Natural Philosopher]

Any boiler is 100% efficient at heat and power production.

The issue is how much of the heat ends up outside the house rather than inside.

[Mark]

I would define efficiency in this context as the ratio of usable energy (i.e. converted into a form or forms that is desired) to total consumed energy. By your definition everything is 100% efficient.

Mark

[The Natural Philosopher]

No, that was YOUR definition.

"Or is it really close to 100% efficiency in terms of electricity and heat production?"

I merely pointed out how useless YOUR definition was.

Don't point it at me.

The whole raison d'etre of CHP is that large amounts of waste heat that can't be economically turned into mechanical/electrical power, is still good enough to do something useful. Like heat houses, greenhouses, farm fish etc etc.

In a domestic situation, a crude estimate of the balance of heat versus electrical power can be gained by examining the sizes of the respective fuel bills. In my case its about 5:1 or so. So a 20% conversion of fuel to electricity (about what a diesel generator does) with the exhaust gases being used to heat water, would be not far off a reasonable mark.

I'd save all my electricity bills, and still pay about the same for heating.

[Edward W. Thompson]

snip

Perhaps I misunderstand you, but diesel generators are far more efficient than 20%, if that is what you mean. If you include waste heat recovery a diesel generator system can approach and perhaps now exceed 60% using heavy (high viscosity fuel).

[nafuk]

Let's keep a balanced argument by trying to reduce fuel use in the first place e.g. wear an extra jumper, use a scythe to cut the grass, buy seasonal veg, walk/cycle to work etc.

[Mary Fisher]

Hurrah!

Mary pedalling away to keep the pc going - well I would if I knew how!

>

[The Natural Philosopher]

I think if you actually look at the power train itself - 30-40% if lucky

- and then whats tacked on the back (by no means an efficient generator) then 20% represents a figure that is not unreasonable.

It doesn't matter as long as you get enough electricity for the waste heat that isn't so wasted un this application.