The future of sustainable energy

MacKay also seriously questions whether Britain could ever generate enough energy from renewable resources to meet its energy needs even if technology was not an issue. Britain (and possibly Australia) may have to look at other options to find sustainable energy.

Are there any other sustainable energy sources on the horizon?

According to the World Nuclear Association, today’s generation of nuclear reactors use an average of 175 tonnes a year of uranium per GW. These reactors are largely using the uranium in a “once-through” cycle where less than 1 per cent of the uranium is actually used to generate energy.

MacKay estimates that the total world recoverable uranium is about 27 million tonnes. This includes resources mineable at less than $130 per kg (the higher-grade resources of around five million tonnes) and lower-grade resources contained in phosphate deposits that will be more expensive to mine. According to the International Energy Agency, because nuclear reactors use relatively little fuel most of the cost in generating nuclear energy is in the planning, construction and decommissioning of the power station not in the fuel. This means that a significant increase in the price of uranium has a much lower impact on the price of electricity. So it is reasonable to suppose that as the cheaper higher-grade resources become depleted the industry will be able to turn to the lower-grade resources.

Using all this recoverable uranium, our current nuclear reactors could operate for 400 years so they would fail the 1,000-year test but comfortable satisfy a 100-year test. But the WNA expects the world’s reactor numbers to more than double over the next few years so our current once-through reactors using uranium may not be sustainable depending on your view of sustainability.

Thorium can be used as an alternative to uranium. It is three times as abundant in the earth’s crust as uranium and is more evenly distributed around the world including Australia. Thorium has the added advantage that, unlike uranium, it can be completely burned up in simple reactors so it creates less long-lived radioactive waste. India already uses thorium in nuclear reactors so the technology is not new, but it will still not be sustainable using current generation reactors.

The newer generation fast breeder reactors burn up all the uranium so they can extract much more energy from uranium than traditional once-through reactors. MacKay estimates that fast breeder reactors obtain roughly 60 times as much energy from the same amount of uranium. They can also use all the discarded uranium from existing once-through reactors. This technology is not new either and several experimental reactors have been constructed over the last few decades but the promising Integral Fast Reactor technology might take several decades to become a commercial standard.

Fast breeder nuclear reactors could be the sustainable energy source we are looking for.

To the Greens this will all be bad news. First renewable sources will not deliver reliable, sustainable energy on their own - at least not in Australia. But worse news for the Greens is that the most likely source of sustainable energy will actually be nuclear power. James Lovelock knew this all along of course.