Will we have enough energy from power stations in 20 years' time? What about our carbon footprint? Is nuclear power a safe option? These vital questions have led me to look again at thorium, an alternative nuclear fuel to uranium. Thorium can help us answer all these questions, but only if our Government commits itself to the development of it as a fuel.

The House of Lords was grappling with these issues last week, in a debate about how nuclear power could help the UK meet its goals for climate change and energy security. It was a timely debate, after the publication at the end of March of the Government's Review of UK nuclear research and development, and the new Nuclear Industrial Strategy.

These two documents give a clear message that we need to increase significantly our nuclear capacity between now and 2050. To avoid dangerous global warming, the review suggests that we need a nearly five-fold increase from current levels of 18 per cent reliance on nuclear energy to more than 85 per cent.

The government report is set against the background of a dramatic increase in oil prices since 2005, and an increasing international gap between the supply and demand of oil since 2010, projections that earth's temperature will rise more than 4ºC within 50 years, and our own Government's committing us to an 80-per-cent reduction in carbon-dioxide emissions by 2050.

Sir David King, the chief scientific adviser to the previous Government, argues that the Italian balance of payments was in the black in 2000, but has now gone €38 billion into the red, of which €34 billion is due to the increased cost of imported oil since the turn of the millennium.

The UK is also moving towards increasing dependency on oil and gas imports because of the fall in North Sea production: now, nearly 80 per cent of our national annual trade deficit goes on increased energy imports. Bankers may have a good deal to answer for with our economic crisis, but so does the cost of fossil-fuel energy.

When most of us think of nuclear energy, we think of uranium solid-fuel reactors, and, probably quite quickly, of Fukushima, Chernobyl, and Three Mile Island. We go on to think of huge quantities of nuclear waste that no one knows what to do with. Not far behind come our concerns about Iran, North Korea, terrorist threats, and nuclear weapons. It forms a sad and worrying list.

Uranium, however, is not the only possible nuclear fuel. It has long been known that an alternative, namely thorium, is at least four times more plentiful, the largest quantities being in Australia, India, the United States, and Norway. Thorium has huge advantages over uranium.

It is safer in several different ways. First, Thorium can be used in molten-salt reactors, the temperature of which self-regulates and can be "switched off" instantly. Second, the way in which thorium is burned as a nuclear fuel means that the radioactive isotopes that are created are less easily used for nuclear weapons, because the thorium fuel cycle produces no plutonium.

Third, thorium creates much less waste, and what does remain is significantly less radioactive and dangerous than the waste from uranium reactors. Most of the radioactive products will become inert within just 30 years, as compared with hundreds of years from uranium reactors.

Furthermore, thorium reactors would enable us to burn much of our existing nuclear waste, which is costing a vast amount to store and decommission. What is currently regarded as "waste" could be turned into fuel, and become an asset.

A bar of the element thorium is as safe as a bar of soap. Thorium itself is not radioactive, but becomes so in the nuclear processes that use it as a fuel.

One tonne of thorium could power a city of a million people for a year. The uranium equivalent is 200 tonnes. It would take more than three million tonnes of coal to provide the same amount of power, which would produce more than eight million tonnes of carbon dioxide to pollute the atmosphere.

YOU might be wondering why you have never heard about thorium before, and why the world has not invested in it in a big way. These are good questions. The answer is primarily that nuclear power and nuclear weapons have been so closely linked since the 1930s that nearly all the research money and time has gone into uranium.

The most significant factor was that the US Navy needed to develop nuclear submarines if it was to be able to "deliver" nuclear weapons. Without that capacity, the US Navy would have had little future.

The research and development needed to bring our knowledge of thorium up to the same level as that of uranium is neither quick nor cheap. China is currently investing $350 million into thorium molten-salt reactors. India has committed itself to thorium research.

There are opportunities for us to work internationally and collabor-atively at the moment, but the window of opportunity might well be closed, if China ends up with advances that it does not want to share fully with others.

There is also scope to build on the existing work being done with Norway, and, to a lesser degree, with France, besides establishing stronger links with the work currently going on in India. We have considerable expertise, particularly in how molten salts behave, that we can bring to the international table.

What we need is: 

• more awareness of the advantages of thorium as a safe, green fuel;

• vastly more money spent on research and development;

• international co-operation;

• a convincing Government-led strategy to enable us to get there. 

The importance of thorium for fuelling the world is too great for its development to continue to be overlooked. The reasons for preferring uranium in the 1930s have now been stood on their head, and have become good reasons for preferring thorium to uranium. Thorium cannot easily be used for nuclear weaponry, has fewer radioactive waste products, can be used at higher temperatures and in molten-fuel form, and is safer and greener. Because of the lead-time of ten to 15 years for research and development, there must be government investment based on clear, strategic thinking. We need this now.

The Rt Revd Anthony Priddis is the Bishop of Hereford, and secretary of the All-Party Parliamentary Group on Thorium Energy.