Clean future in nuclear power

We may not be getting an emissions trading scheme any time soon but the climate and energy crises still need fixing with real urgency.

For climate, the issue is excess greenhouse gases from burning fossil fuels. For energy, the crisis is dwindling supplies of those fuels and air pollution from coal combustion.

Replacement energy sources need to be reliable, plentiful and economic to deploy. They need to be low-carbon to minimise global warming. Business-as-usual or half measures risks saddling future generations with a climatically hostile planet and energy scarcity.

Nuclear power is one obvious replacement source, but typically raises five objections.

First, readily available uranium supplies are limited. If the world was wholly powered by present-style nuclear reactors there would be at most a few decades of energy before cheap uranium was exhausted.

Second, nuclear accidents have happened in the past, suggesting this technology is dangerous.

Third, expansion of nuclear power would risk the proliferation of nuclear weapons.

Fourth, we would leave future generations with the legacy of long-lived nuclear waste.

Fifth, large amounts of energy (and possibly greenhouse gases) would be required to mine, mill and enrich uranium and to build and later decommission nuclear power stations.

All the above points have merit, although their relative importance compared with climate change and critical energy shortages is debatable. But there is little point in debating these objections because none will apply to future nuclear energy generation.

Almost all today's nuclear power stations are thermal reactors. These use water to slow the neutrons that cause uranium atoms to split (fission) and to carry the heat generated in this reaction to a steam turbine to generate electricity.

Because of the gradual build-up of fission products (neutron poisons) through time, we end up getting less than 1 per cent of the useable energy out of the uranium. The rest is thrown out as that long-lived waste.