01 March, 2006

Why it’s time to junk the National Grid

This post continues from where I left off in the last.

You could argue that I’m being premature by slagging off government energy policy when they’ve not announced it yet. But there is a clear intent to put nuclear back on the table, both in public statements and in the consultation document itself, which (if you like your statistics well-supported, look away now) mentions “nuclear” 108 times in 77 pages, in comparison to only 55 times in the much longer (142 pages) 2003 White Paper.

It won’t work.

Firstly (and forgive me for recycling old material here), electricity generation accounts for only 35% of our energy usage, so as the consultation document itself points out:

… even if we had a completely carbon-free generation mix but took no measures in other sectors, we would fall far short of our 2050 target.

And, again repeating myself, if you take into account the costs of refinement and decommissioning, nuclear power is only carbon free at the point of generation (incidentally, I can now point you directly to the work of Jan Willem Storm van Leeuwen and Philip Bartlett Smith here). Once we start refining low-grade uranium ore to meet the increased demand of new nuclear power stations, we may well use more CO2 than we save at the generation end. Besides, replacing fossil fuels with uranium is merely replacing one non-renewable energy source with another (from a geological perspective, a less renewable one); current known uranium ore reserves will last no more than 50 years even at present levels of demand. As a…ok, the, commentator on my first post pointed out, this ignores the potential of reprocessing and breeder reactors, but these are technically difficult and expensive technologies, which is why they’ve never been taken up in a big way in the first place.

To be fair, the consultation document does actually refer to these facts, (although it hides them in one of the appendices); the argument seems to be that nuclear is still the best option despite them. Renewables are not being ignored, and are projected to generate 15% of our electricity by 2002 (up from <5% now), but problems of cost and the intermittent supply they add to the National Grid seems to prohibit them from taking up a larger role. So, the government seems to be concluding that there is currently no sustainable solution other than using the nuclear option to buy time while we wait for some amorphous ‘new technology’ to appear and fix things overnight.

However, this gloomy outlook ignores a wide potential avenue for cutting emissions. Our energy distribution system dates back many decades, from a time when coal was our major source of energy. It made sense to export electricity rather than fuel from the isolated coal mines, so the present system of generating electricity at big power stations and then distributing it around the country via the National Grid was developed. But this system has disadvantages: about two thirds of the energy in the fuel driving the turbines is lost as waste heat, both at the power station itself and from resistive heating in the power lines and transformers of the transmission system.

Ironically, heating accounts for the overwhelming majority of energy usage in the domestic and industrial sectors. This coincidence has led to the development of cogeneration – a combined heat and power (CHP) system where waste heat from power generation is used to heat water for supply to local buildings. You save twice, because you’re wasting less of the energy released by burning fossil fuels, and you don’t have to use additional energy to provide space heating.

The problem is that the benefits of cogeneration are limited when you have a small number of big, widely distributed power stations, because it is only practical to heat buildings which are close by. What is needed is a more distributed generation network, with many smaller cogeneration plants supplying electricity and hot water to the local area. This is no theoretical pipe dream, either – a scheme in Woking has cut the emissions for council buildings by 77% in the last 15 years. I was surprised to find out that we even have a scheme here in Southampton.

Therefore, rather than replacing our large, isolated power stations with more of the same, why not build a distributed network of smaller cogeneration plants? We even have the gas network in place with which to fuel them! Such a strategy is explored in some detail by a Greenpeace report here (pdf – discovered via Camden Lady who has posts on this subject here and here - see also the World Alliance for Decentralised Energy site). They suggest that natural gas can be used as a ‘bridging technology’ to develop a distributed infrastructure, which can gradually incorporate more renewable energy (intermittency is less of a problem for a local grid, where demand is also intermittent, and heat and battery storage technologies are more practical), and any new technologies, such as hydrogen power, as they develop.

Thinking globally, it is obviously no good for the UK to just cut our own greenhouse gas emissions, which account for only 2% of global output, if the rest of the world does not follow. Leading the way with distributed generation technologies will show developing countries, which don’t have a national electricity network, a more environmentally friendly way to industrialise (not to mention being a nice little earner for us).

Even the consultation document admits that there is some promise in this area (although dodgy statistics show that distributed generation is down to 3 mentions from 27 in the 2003 White Paper):

Micro electricity generation technologies (including micro-CHP) could potentially provide up to ~30 to 40% of UK electricity demand by 2050 given the right market conditions.

But this has already been achieved in northern European countries such as the Netherlands and Denmark. Do we really need 45 years to catch up with them? The relative lack of enthusiasm (reflected by the fact that our current regulatory framework makes setting up local power generation very difficult) apparently stems from thinking that smaller-scale power generation is something which needs to be bolted on to the existing system, rather than replacing it. And the time is ripe for replacement:

Maintaining the reliability of electricity supplies will require very substantial levels of new investment as … ageing distribution networks [are] maintained and renewed

Billions of pounds are going to be needed in the next few years to upgrade the National Grid. Why not change it instead, whilst our energy destiny is still in our own hands? It’s probably not as simple as I’d like to think. Maybe the changeover to a distributed system would take a long time, maybe we’d still need some new nuclear power stations to help bridge the gap (I can’t see why but you never know). But I’d like to see it as the target. I’d like to see the government show some real vision.

2 comments:

Hughes Views said...

You're right - it's not as simple as you make out. There are good reasons why countries have developed grids to carry electricity. Mainly because it isn't practical or desirable to generate the stuff close to where it's needed. Localisation would result in highly unreliable supply and dreadfully inefficient conversion of other forms of energy into electricity. It would be an environmental disaster.

Unfortunately the debate has been taken over by lobby groups rather than engineers......

CJR said...

There were good reasons for the development of grids - we used coal, which is difficult to transport and dirty to burn, to generate electricity. It seems to me that those reasons are far less compelling now than they once were.