Whatever one’s politics, it’s indisputable that, as long as we can tap into it practically, there is plenty of renewable energy coming ultimately from the sun to give us stability over not just years, but generations. At the other end of the uncertainty scale is nuclear, with huge capital costs, potential risks, long ‘lead time’ and waste that will remain dangerous for longer than human beings have been civilised. Somewhere in between lies the promise of ‘clean coal’ and Carbon Capture and Storage (CCS) - technologies which seek to minimise emissions while continuing to deplete a finite resource, effectively kicking the ball into the long grass for future generations to pick up.

Set out so simplistically, it’s hard to see why there should be a battlefield at all, so the core question is ‘Can renewables really deliver?’ And if they can, it boils down to ‘How quickly can we transform from fossil and nuclear to renewables - not just for electricity, but also to supply energy for heat and transport?’ Where there is controversy is the order in which we put sustainability, security and cost when taking decisions today.

In the longer term only renewable energy is sustainable – ie, indefinitely able to be continued without damaging vital environmental or social systems; secure - available to our society without conflict; and affordable - at prices that do not exacerbate social injustice or disrupt economic stability. Today however, renewable energy is not seen as secure. Even though it is largely immune to interruption by terrorists or dictators, the wind doesn’t always blow, and the sun doesn’t always shine. Yet in an increasingly renewable system, security will rely on smart management, deferrable demand, and energy storage to make efficient use of the resource – rather than on simply building ever more generating capacity.

And today renewable energy is also relatively expensive – because the damage done by conventional energy is not fully costed in the price we pay at the meter. However, the best approach to affordability is to manage demand through conservation and efficiency, thus reducing bills even if unit costs are higher. And unit costs rising aren’t a bad thing as it drives efficiency across the economy. In fact, cheap and plentiful energy resources can be a curse for economic development, rather than a blessing. Economic growth in US states with low energy prices has lagged behind those with higher costs, and developing countries with plentiful oil but weak governance and institutions – such as Nigeria – have suffered from the ‘resource curse’ as control of oil has become a battleground.

In fact, energy saving wins hands down on all three key criteria – the watt of energy we don’t have to produce is the cheapest, the most secure and the least environmentally or socially damaging. So energy conservation should be at the top of our ‘energy hierarchy’, in the same way that waste prevention sits at the top of the European Union’s official ‘waste hierarchy’.

So where do other options come in the hierarchy? Nuclear energy is the ‘landfill’ of an energy hierarchy – right at the bottom. In the short term, nuclear energy may remain as a necessary evil. Globally it will be used, because it makes sense to make best use of whatever currently exists. But countries that have it should work to phase it out, and those that don’t will be best served by avoiding the nuclear ‘dead end’. Simply think of the ‘opportunity costs’ (that is, what else you could be doing with the same money) of the nuclear industry.

Official analysis for the UK government says that by the time new plant could be in place, nuclear power would cost around 30% more than wind power per unit of electricity generated. And our track record isn’t good: the UK’s last reactor at Sizewell B spent seven years in planning and eight in construction and cost double the initial estimates at over £3.0bn… and that is before the costs of decommissioning and waste management liabilities, which official estimates suggest will greatly exceed £50bn for the UK’s existing nuclear programme.

Going back to the top of the hierarchy, energy conservation (insulation rather than heating, walking rather than driving) blurs into energy efficiency (efficient buildings, appliances and vehicles). Both of these will require government funding and other interventions - such as requiring homes to be upgraded to tightening standards at the point of rental or resale, with generous grants for those who can’t afford to make improvements themselves. In Germany the government is leading a 20 year programme with soft loans provided by a state investment bank to improve all homes to modern standards. This is not only cutting emissions, but creating tens of thousands of jobs.

Next in the hierarchy come the renewables, generating energy once you’ve already done everything possible to conserve it. Decentralised and community scale generation are preferable, especially for heat where local biomass or anaerobic digestion of green wastes is most efficient at a small scale, but we will also need more centralised large scale wind, wave and tidal farms.

The ranking of what’s left in the middle of the hierarchy, based on continued use of fossil fuels - is the least clear, but when carbon is the key criterion, gas is better than coal, combined heat and power is better than electricity generation only, and Carbon Capture and Storage (CSS) is better than what’s known as ‘unabated’ (what we might call traditional power generation). In fact, it could be argued that unabated coal power is a competitor with nuclear for the bottom slot in the same way in which incineration competes with landfill as the worst option for waste disposal.

Is this a dreamland? Some might think so, but the evidence provided to policy makers by Garrad Hassan in a recent report for Friends of the Earth Scotland, The Power of Scotland Renewed is that Scotland can virtually decarbonise by 2030 without nuclear, or coal, or even gas. The challenge for Scotland is not a shortage of energy generated, but system management to handle large amounts of renewable energy, including the transfer of heating and transport infrastructure from oil and gas to electricity. Indeed, our anticipation is that as a result of plentiful renewables, especially marine, Scotland may even become a preferred location for power hungry development such as data centres.

But not everywhere can follow Scotland’s trajectory. Climate justice requires that the emissions of rapidly industrialising poor nations such as India and China should be allowed to fall more slowly than that of rich nations, and indeed that their emissions may even be allowed to grow for some time yet. It is in these nations, rather than in post-industrial societies such as England and Scotland, that Carbon Capture and Storage (CCS) will provide a key bridging technology. But CSS can’t be allowed to become an excuse for continued reliance on fossil fuels in the rich world. We don’t need and shouldn’t be constructing new unabated coal plants in Britain on the promise of future installation of carbon capture.

But why do we continue to get it so wrong, when there’s so much evidence around as to how to do it right? The answer lies in recognising that the commercial drivers of energy policy, especially in liberalised energy markets, don’t really value sustainability or security. Commercial interests such as multinational companies dominate energy markets. They influence government policy in ways such as threatening to switch investment between countries. And trade union interests get tangled up trying to protect existing unionised jobs in conventional power generation, rather than backing new jobs in decentralised energy saving and renewables.

It’s no wonder energy has become a battleground, but consumers and the environment will continue to be the casualties of the battle until governments focus on, and aggressively pursue, the energy hierarchy I’ve described.

Duncan McLaren has been Chief Executive of Friends of the Earth Scotland since 2003 and has led the organisation in successful campaigns against nuclear power in Scotland, for a tough Climate Change Act and for improved waste recycling. In 2008 he was surprised to be named among the 50 most influential people in Scotland by the Scotsman newspaper.