Storing Electrical Power In The Grid...

4th January 2008

This is a letter from one of the members of the group to me. My reply is below (but I only sent it today (24th) - it was lost in my Drafts folder - D'oh!

Hi,
I've been watching your exchanges with Derek re the above and whilst I admire your interest in renewables, I am forced to the conclusion that you have no grasp of the nature of, at least, the UK power supply system. If I'm wrong, then I apologise.

My background is in power systems and I remember 35 years ago strongly advocating CHP systems with several letters in the press (FT, Times etc) but for several reasons, CHP has never come about in the UK. I concluded that the most powerful reason was that the UK generation system had developed along lines where the big base load power stations (PS) were chosen (a) for maximum thermal/electrical efficiency, (b) for the availability of suitable cooling water supplies, and (c) for the proximity to coal mines and/or coal import terminals.

Given that the UK is an island surrounded by water and sitting on huge supplies of coal, this policy resulted in the system we know which is capable of delivering a peak demand of 70GW - that's 70,000 MW, the equivalent of 35 - 2000 MW PS, and is the largest interconnected, synchronous grid in the world with an extremely high availability and immunity from various perturbations, whilst maintaining statutory limits on voltage and frequency. By its nature, it comprises PS remote from load centres which is why we have the 400KV supergrid.

Energy sources cover nuclear, gas, coal, oil, hydro, wind, solar and the first 5 have all been heavily developed over the years and all require massive capital investments and lives of many decades. It is a technical fact that such a system cannot accept, i.e. cope with whilst meeting system stability criteria, more than 10% of power depending on variable sources such as wind and solar, which means that these sources are inherently self-limiting. This level has already been met in Denmark, Eire and Germany and it is just unrealistic for idiots such as George Brown to "commit" to 20% of our power coming from wind turbines within 20 years, and he is very badly "advised" on this issue, as are most politicians.

All the hydro power which is economically available in the UK has been developed, and the only further steps that could be taken would be to import hydro power from Iceland by undersea DC cable - a project to do this has been under consideration for many years and I hope it will happen.

That leaves wave/tidal power, which has been investigated and even trialled in some places but there are huge technical hurdles to be overcome, prominently that of sheer survival in the marine environment during stormy weather. Norway has near perfect fiord sites and many trials have tried but failed to survive the tidal forces, even if its just once in 10 years or so.

Tidal schemes are represented only I believe in the Rance scheme in France, some 30 years ago, but it is of small effect/value. The Severn barrage would of course be technically useful but the environmental lobby is a powerful one - even so, the output would be significantly variable.

So, wishing for something doesn't make it useful/feasible/economic and we are stuck with what I have outlined above. Nuclear offers the best prospect with fusion techniques and has a power density that can contribute significantly as we have seen in France. One has to think in terms of Gigawatts not Megawatts due to the magnitude of the industrial load and there is just not available any renewable source of energy of that order that can meet the criteria I have outlined above.

The world is awash with coal which can be cleaned and is available from politically stable sources including domestic, and it is a tragedy that political factors did such damage to UK coal mining in the 1990s - but that's another chapter. The Germans didn't fall into that trap and are currently building 27 new, clean, coal-fired PS fired with domestic coal - they're not daft!!

Hope that helps your understanding of the energy scene.

Regards

John

Sent 24th January 2008

Hi John,
thank you very much for taking the time to write to me.

I was aware of the principles of how our energy system currently works, and I realise that the current infrastructure isn't designed to handle wide fluctuations (eg from renewable sources)... Specifically, that the grid itself isn't designed to store power. That, as I understand it, would be the essence of the problem. Please correct me if I'm wrong.

The fact that the grid currently isn't able to store power doesn't mean that it's impossible for it to - or indeed that it's not desirable for it to... I'm aware of a number of techniques for storing electricity - including flow batteries - that could be employed to do so... Admittedly the scales are large - but then building nuclear power stations involves quite a bit of engineering too...

You say 'All the hydro power which is economically available in the UK has been developed' and I'm sure you're right - but the key phrase kas to be 'economically available ' - and that depends a lot on legislation...

Everyone seems to be looking for big solutions to the apparently big problem of energy supply. I think the answer is not in a few tens of big power stations, but in millions of power generators of all sizes (from homes upwards).

When I look at my local area I can see the following small-scale sources of renewable energy which are, as yet, completely unexploited - because they are 'economically unavailable':

• Private/business residences - none have solar cells (PV or vacuum), none have wind gens.
• The neigborhood rubbish is buried instead of being burnt & converted to electricity.
• The neigborhood green waste is composted but it could be burnt or methane digested...
• Our sewage is not methane-digested (& converted to electricity)
• Our local river (the Ouse) has many locks & wiers - most near the grid - none of which have water turbines.

The only reason these are not economically viable is legislation...

Home Power Systems Aren't Rocket Science

It's easy to make homes self-sufficient for heat - with good design, or failing that - using evacuated solar tubes. Around £2000 is plenty to provide all a home's heating year-round. You can also use heat exchangers or wind turbines for heat too.

Solar electricity is still too expensive (1kw system is $8000), but the technology is moving fast - and cheap printed solar cells will probably be here before we can build a new set of nuclear stations...

Wind generators aren't suitable for everyone, but they work very well for some in rural areas. If the buy-back restrictions were lifted, there are hundreds of farmers who would start selling wind-power back to the grid within months.

A Brave New Energy Supply System:
The Consumer Becomes The Producer

I ask here that you indulge me a little, and please try to image, for arguments sake, what would happen if the following conditions were set:

1. All electricity meters in the country were switched to 2-way, and the restrictions on selling back to the grid were abolished.
2. Buy-back tariffs on renewables were set to a profitable level.
   - now anyone can sell any amount of energy back to the grid at a reasonable price.
3. All renewable energy installations are tax-deductable. (e.g. from your Council Tax bill)
   - now it costs homeowners nothing to install these systems - and it makes them money. Everyone will do it.
   - It'll cost the government as much as £5000 per home - and for 22M homes that's 110Bn (which is actually not that much...)

(Alternatively, I think that just removing all taxes and as much regulation as possible from the sector would have a similar, but slower effect for less immediate cost)

- This would mean that 100% of heating needs in the country were met renewably, and a good proportion of the electricity needs (22m x 1Kw= 22Gw peak - assuming 1kw per house).

Note, this figure doesn't include any generator bigger than a private house... If these are included too - then assuming we can store all this energy ;^) - we would have plenty!

If the consumer became the producer as in this scenario - energy efficiency would skyrocket - because people would effectively be selling the energy thay have 'saved' back to the grid automatically...

I look forward to your reply.

Regards

Next Installment

David Cameron Has Been Paying Attention

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