Friday, 27 February 2015

Can Nuclear Fusion save the world?

When some of the graduates went to the KIT summer school on Fusion technologies last year (see blog post here), David Ward from CCFE gave a talk entitled ‘Future Energy and the Role for Fusion’. As well as leading CCFE’s Power Plant Technology Unit, David works at the Oxford Institute for Energy Studies, so is well placed to give an overview of fusion’s place in the energy market of the future. It was so well packed with interesting facts and figures that I thought I would convert his talk into a blog (with his permission!)
Future outlook
Most people are aware of the dire consequences facing the world at the moment due to global warming.  We’re beginning to see more and more examples of extreme weather globally and this has been partly attributed to all of the carbon dioxide that developed countries have emitted since the industrial revolution. Unfortunately the areas that usually get hit the hardest by this extreme weather are developing countries: nations that have contributed the least to these effects.

The graph below (Fig 1) shows the HDI (Human Development Index – a measure of GNP, health, education, etc.) for all OECD (developed) and non-OECD (developing) countries.  For all developing countries to reach the same HDI as the UK for example (~0.9), the world’s energy use would need to double, not accounting for any population increase. 

Figure 1

Figure 2 shows a graph of the energy consumption in Germany, China and India from 1965 until 2010. It shows that in just the final two years the growth in Chinese energy consumption has equalled the total energy consumption by Germany since 1965. Developing countries are becoming a match for energy consumption from developed countries. We must reduce emissions if we are to minimise climate change, yet we are faced with a massive increase in demand for energy. Decoupling this paradox will require dramatic changes in energy systems.
How can fusion help?
Renewable energy is making progress, and is steadily forming a larger proportion of energy production. In 2013 renewable energy contributed 15% to UK electricity compared to 11% the year before. Renewables have an extremely important part to play in our future, but many of them rely on certain weather conditions (solar, wind) and at the moment we do not have a viable energy storage solution (although progress is being made). Nuclear fission provides a reliable baseline energy supply with low carbon emissions, and fusion has the potential to do the same in the future, with even more advantages.
One of the fuels used in fusion is deuterium, which occurs naturally in water. A single litre of water contains 0.033g of deuterium, possessing energy equivalent to 10GJ or 280 litres of oil. There is enough deuterium around to provide energy for billions of years. The other fuel is tritium, which can be produced from lithium. The amount of lithium in one laptop battery would be enough for one person’s lifetime of electricity needs (240,000kWh). There are land based lithium reserves for at least thousands of years (from known supplies) to millions of years (from expected but unconfirmed reserves). The bottom line is that fuel reserves for nuclear fusion are enormous and not an issue.

Nuclear fusion is inherently safe – there is no chance of a ‘run-away’ reaction. Tritium is radioactive but has a short half-life of 12.5 years, so it decays quite quickly (long-lived fission products have a half-life of up to 200,000 years). It’s useful to put the amount of radioactivity we experience in our day-to-day lives in perspective. Figure 3 shows the amount of radiological exposure arising from activities which give us energy. The two highest doses are from food, and from improved double glazing – both of which go off the scale of the graph. Food is naturally radioactive, and double glazing increases our dose by introducing more radon into our homes. This graph is just to give context, and not compare means of energy consumption. None of these sources give us a damaging amount of radiation.

Figure 4 shows a 2007 prediction of the lifetime of various energy sources, assuming current demand. There is data for oil, gas, coal, uranium (for fission), breeder (for advanced fission) and lithium (for fusion). For each there is a ‘lower resource’ - what we know we have, an upper resource - what we think we may have, and ‘new’ resources - speculative considerations. These data are rather out of date, and do not include shale gas reserves but give a good overall idea of the future we face. Oil, gas and coal are probably going to run out very soon, and even if they don’t we need to curb their usage. Even uranium for fission doesn’t give us a very long outlook. Advanced fission reactors and fusion would see us far into the future, with very low carbon emissions. 

Fusion’s bad press

There are lots of good things about nuclear fusion, and when we get it working, it has the potential to largely solve our energy problems. However, it has had rather a bad press in the last few years. The typical joke is that ‘fusion is always 30 years away’. What rarely gets reported is how much progress we have made in fusion, the technologies that have advanced due to fusion research, and how much we now understand relative to even 10 years ago. What often gets reported is that we have an international project called ITER, which will be the largest fusion reactor so far, and for which construction has overrun and has gone over budget. This is true, and the management of the project is now being reorganised to address these problems. The estimated total cost of ITER is 15 billion euros, which is a huge amount of money, but it’s interesting to compare this to other costs. The total cost of ITER amounts to the same world expenditure on two days’ worth of oil. Figure 5 shows the estimated amount spent globally on different energy sources. Overall, the amount spent on public sector research and development is a negligible fraction, and of that, fusion is a tiny fraction.
The Future
If we consider hypothetical future energy scenarios, in a world where there is no constraint on carbon emissions, we are totally dependent on coal and fission. In a low carbon future – fission and renewables provide the growth needed for about 50 years. After that, fission needs to be replaced by ‘advanced nuclear’ which includes fast breeders and fusion. Alternatively, fission may be constrained due to public concerns and fusion may be required earlier. However, if fission is rejected by the public, it is uncertain whether fusion will be more or less likely to contribute meaningfully.

World energy consumption is likely to more than double, even with a cap on it. There is therefore an enormous potential market for low pollution, low carbon energy sources. Fusion has huge benefits in terms of resources, environmental impact, safety and waste materials. Those doing research into fusion power must focus on demonstrating its potential as a power source, ensuring the benefits are optimised and keeping costs reasonable. If we are to achieve the transformation required in energy markets, the world needs to invest much more in fusion and in energy research and development as a whole.

For more information please see David Ward’s publication

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