Nuclear power will not deliver a solution to climate change. For example, the UK Prime Minister's advisers, the Sustainable Development Commission, calculate that a new reactor building programme would cut greenhouse gas emissions in the UK by just 4%.

Given how hugely controversial a new nuclear programme would be, this is not a big gain for the amount of political and policy focus the initiative would require, especially when so many other policies on efficiency, transport, planning etc. are crying out for vigorous and sustained attention. Politicians will not be able to get nuclear power stations built at the same time as delivering in other areas that will create major greenhouse gas savings. If anyone doubts this, just look at the UK's renewables policy and failure to get new renewable technologies moving.

Decentralizing

Another problem with constructing new nuclear power stations is that the move props up a system of big, "centralised" power stations that waste a great deal of heat. Currently UK power stations waste enough energy to provide space and water heating to all UK building stock.

Greenpeace advocates a decentralisation of power supply that allows the heat currently wasted to be used in nearby buildings, and enables many more actors to play in the energy system. A power sector with more players than the 'big six' utilities would be better for the climate: a study by consultants to the UK Foreign Office, Canadian and German Governments indicates that decentralisation of the UK power supply system would, over 20 years, provide a 17% cut in CO2 emissions and a 14% cut in gas use compared to a conventional centralised system largely based on modern gas stations alongside nuclear new-build.

The decentralised system would also be cheaper because local power removes the need for expensive upgrades to electricity grid infrastructure. The IEA estimates that in the Organisation for Economic Co-operation and Development (OECD) grid renewal will cost as much as generation plant up to 2030; connecting power stations to where the electricity is used is a major cost.

Nuclear downsides

Nuclear power has major downsides. Here are just a few of them:

1. Nuclear waste - no one has cracked this problem. There is an oft-repeated comment that the technical problems have all been solved and it's just the political issues that need to be sorted. Even assuming this is true, why does it need saying? For most, or even all, major environmental problems the technical side can be sorted but the politics are the problem. There are some technical challenges with nuclear waste that are formidable - dealing with heat-generating high-level waste is not like handling any old rubbish. Putting it underground is like burying a kettle which is plugged in and switched on. And we need to be sure it's kept safe for many thousands of years. Sweden, Finland and other countries all feel they have made progress but none has a "solution". In particular there is an enormous difference between a Scandinavian community agreeing to house a defined quantity of waste, and taking an open-ended commitment to house a great deal more fromhowever much waste a future nuclear programme might generate. In the case of the UK, there would be a fourfold increase in spent fuel and high-level waste from a new build programme.

2. A global solution? The atmosphere doesn't care whether CO2 is emitted in Harrogate or Harare. In climate change policy, much is being made of the developed countries' responsibility for technology transfer. So if nuclear power is the answer (rather than local renewable energy, for example) would nuclear stations be appropriate for Afghanistan and Somalia? Those who advocate nuclear power as an answer to global warming need to have a good answer for this question but I've never heard one.

3. Proliferation. Why is it alright for Western nations to have nuclear power and not Iran? Western fears are driven by worries over nuclear weapons proliferation, because a great deal of the technology, handling and skills in a nuclear power programme is similar to that in weapons development. How much more difficult will it be to stop weapons proliferation if lots of countries have access to nuclear power technologies?

4. Terrorism. There have not been many concerns expressed about airliners crashing into wind farms or suicide bombers getting access to a solar panel array. All nuclear power stations (and the associated fabrication plants, transport of fuel/waste etc.) have human systems that will be fallible.

5. Levels of support. Given the above, no nuclear programme can exist without the full support of government. Generally that support has gone beyond security to financial, legal and institutional backing over many decades. Despite this, major question marks remain over the financial viability of new nuclear power.

To summarize my views, nuclear power is not the way forward. Instead we should be aiming to decentralize our power systems and make the most of diverse renewable energies and the waste heat from fuel burning.