Just how do we keep the lights on?

By David Shukman
Environment correspondent, BBC News

The threat of blackouts. Rising scepticism about climate science. Disarray in international efforts to tackle climate change.

Whoever wins the next election faces an exceptionally tricky tangle of challenges linking energy and environment.

Put simply, the most fundamental question is this: How do we keep the lights on while cutting our emissions of greenhouse gases?

The starting point is that our oldest coal-fired and nuclear power stations are being phased out, so difficult decisions are looming about how to replace them.

At first sight, the easiest answer - and the cheapest - would be to quickly build a new generation of stations powered by gas or coal.

But that is not an option because the UK is committed to lessening its reliance on fossil fuels.

The Climate Change Act sets out cuts in emissions of 34% by 2020 and 80% by 2050 compared with 1990 levels. And the three largest parties are all behind it.

Growing energy demand

That limits the choices for how the UK can generate its growing demand for energy - and each one has pros and cons.

Home energy use is a big contributor to the country’s carbon footprint

One option is for a surge in wind power on land and out at sea.

But onshore turbines risk a backlash from residents and campaign groups while offshore the costs are extremely high and the engineering uncertain.

Labour and the Liberal Democrats favour a big push on both; the Conservatives' plans emphasise offshore.

Another idea - backed by all, though in different ways - is to explore green schemes for using coal, the dirtiest fossil fuel.

This would involve burning coal but trapping and burying the resulting carbon dioxide before it is released.

This is being tested on a small scale, but no-one has tried it for real so the pricing and logistics are unclear and the regulatory framework disputed.

Nuclear power is back in favour with Labour and the Conservatives as a low-carbon source of energy and new nuclear stations are planned.

But the small print of liabilities and costs is not settled and the Lib Dems are opposed to an atomic revival, fearing a diversion of resources away from renewable energy.

Rising bills

Whatever the eventual mix, one thing is very likely; householders will see their energy bills rise.

To counteract that, all parties have plans for helping improve the energy efficiency of millions of homes.

The next government needs to make cars greener or tempt us out of them

Measures range from fitting new boilers and insulating lofts to encouraging home-grown energy production - decentralised or micro-generation - where anyone producing power can sell any surplus back to the grid.

Residential energy use is a major contributor to the country's carbon footprint so boosting efficiency and on-site generation should cut emissions and could see an eventual fall in bills.

The exact arrangements are hotly disputed.

The challenge will be convincing people that the cost of the investments and the hassle of the measures themselves are worth it.

And then there is the thorny question of how we get around - another large source of greenhouse gases.

If the UK is to meet its targets for cutting emissions, the next government will either have to push rapidly to make cars greener - maybe by going electric - or do more to tempt us out of them and into better public transport.

Unlike in the US and Australia, the UK has for several years witnessed widespread political consensus on the threat of climate change and the need to act on it.

The arguments are over exactly how to respond. The choices are hard and the timetable tight.

One option put forward by the Conservatives is to reform the Climate Change Levy to encourage investment in low-carbon energy production, with the proportion of tax revenues generated by environmental taxes increased.

Labour, meanwhile, have pledged that about 40% of electricity should be generated through low-carbon technology by 2020.

Energy strategy and climate change targets are UK wide, however planning and home energy efficiency are largely devolved to the national assemblies of the UK.