A look at how Fusion energy works and its future for global energy
Oil and gas remains and will continue to be an important fuel, accounting for 31.3% of total world energy supply in 2014, followed closely by coal (28.6%) and natural gas (21.2%). However, governments are under increasing pressure to hit carbon targets whilst also decreasing the capital and running costs of renewable energy projects.
Cue fusion, the process that heats the Sun, which promises cheap, safe, clean, and abundant energy. But is it feasible to harness this great energy and create a commercially viable energy source?
In this article we look at how nuclear fusion works, the benefits and challenges of making fusion a commercial reality, where we are now and an outlook of where fusion is heading.
How fusion energy works
Fusion is defined as the joining of things together, whereas fission is the splitting of things. Existing nuclear power is generating power by the latter, splitting heavier atoms into lighter atoms. Scientists are currently working towards combining nuclei to form one heavier atom, releasing energy in the process (four times as much as nuclear fission). This is the process that powers our own Sun and is called nuclear fusion, first theorised by English scientist Arthur Eddington in the 1920s.
To achieve this, two types of hydrogen (deuterium and tritium) are heated to over 100 million degrees Celsius to form plasma. This plasma then becomes helium and high-speed atoms under the immense heat, releasing a lot of energy in the process which is then converted to heat to drive turbines through the use of steam.
Due to the fact that the plasma is extremely fragile, it needs to be kept from cooling and contamination. Although there are various ways to achieve fusion, one of the most common methods is to use a circular containers called a tokamak. This is a magnetic confinement system usually in the shape of a doughnut that Russian physicists first proposed in 1950s, which suspends the plasma in mid-air to prevent cool-off and contamination.
Benefits of fusion
If scientists can crack the fusion conundrum, then it will provide a host of benefits. Fusion power would be clean, with no pollution, no carbon dioxide, and minimal nuclear waste (unlike nuclear fission).
We also have abundant fuel for fusion power (deuterium is distilled from water and Tritium can be produced during the fusion reaction itself through contact with lithium, which we have an abundance of in the earth and the sea). Related to this there are geopolitical benefits as these resources are available to all, avoiding monopolies which in turn could reduce conflict across the world.
It’s also safer. Large meltdowns seen in fission nuclear reactors like Chernobyl are impossible due to the tiny amount of fuel used and the temperamental nature of the plasma (even if the plasma is disturbed for a couple of seconds, the reaction comes to a halt).
The benefits are widely recognised, and the process is scientifically feasible, but the biggest question is whether fusion can be practical. Fusion that happens in stars (including our Sun) is created from huge gravitational forces creating pressures and temperatures that create fusion naturally. However, we need to try to manually energise the fuel and then hold onto the plasma, the two main challenges that face scientists looking to create a commercially viable solution.
To make two atoms fuse you have to push them closer and closer together, but every nucleus in an atom has a positive electrical charge which repels other nucleus. The nearer they get, the stronger the force becomes (quadruples every time you halve the distance) and hence you need to put in a huge amount of energy. Break even point is when the energy given off by the fusion of two atoms is enough to cause other atoms to fuse together, creating a self-sustaining cycle, and thus a fusion plant that is viable.
In experiments so far, more energy is put into the process than it produces and no scientists have broke even. Plasma has been heated to over 900m degree Fahrenheit, and plasma has been sustained for 6.5 minutes, but these two records were not at the same time and at two separate locations.
However, it isn’t just technological difficulty. Funding is also a problem. Fusion projects across the world have costs billions of dollars in total and in 60 years of research they still haven’t produced net energy. This is hard for policy makers to justify to taxpayers when there are immediate challenges being faced in the world. Dependent on your views, fusion is either a clean, abundant, safe, and relatively cheap energy source that we must invest in to ensure it becomes viable; or it is an unproven and expensive wager that takes money away from areas of society that really need it.
Once more, given the currently substantial research and set-up costs, current projects are also heavily reliant upon a collaboration between countries. However, collaboration can also lead to division and if one country's funding priority changes then it could jeopardise the success of an entire project.
The largest tokamak reactor in the world is in England and is called the Joint European Torus (JET), which was commissioned in the 1970s and upgraded in the 1980s. It holds the record for the most energy produced in a fusion reaction, but still hasn’t reached the breakeven point.
As many believe that fusion plants get more stable with scale, the largest fusion project involving the EU, USA, India, China, Japan, South Korea, and Russia is currently under construction in the south of France. ITER, which stands for International Thermonuclear Experimental Reactor and also Latin for ‘the way’, is an €18bn project that is scheduled to make its first plasma in 2025 with maximum output at 2035. Compared to the current 16MW output power and 24MW input power record of JET, ITER will aim to produce 500MW of output power from 50MW of input power, ten times the amount put in.
The megaproject has some impressive statistics:
- The facility will span the equivalent of 60 football fields
- The reactor building will weigh 320,000 tonnes, and the reactor itself 23,000 tonnes
- 2,800 tonnes of superconducting magnets and 200km of superconducting cables will be used
- Some of the magnets are heavier than jumbo jets
- The tokamak will have a 30 meter diameter
- 12,000 litres of liquid helium will be pumped per hour for just 2 grams of plasma
- 4,000 workers will be involved in the project
Future outlook for fusion
ITER focuses on increasing the scale of the tokammak but as a result requires huge investment, scale and collaboration. However, research is currently being undertaken in more compact, apple-shaped spherical tokamaks. Historically more difficult to build, research was recently published tackling one of the most difficult elements of this type of design - the shielding of the centre. These kinds of technological advancements may open up further fusion advancements without the costs of scaling up to ITER proportions. Projects in Asia are also making progress by focusing on holding plasma for longer as they look at superconducting magnets.
Fusion clearly has the scientific potential to be a sustainable future energy source and progress is being made (albeit relatively slow over the course of 60 years). The determining factor of fusion’s future success is largely the geopolitical element, and two significant changes that have happened recently highlight how shifts in politics can influence fusion’s advancement: the UK voting to leave the EU and Donald Trump becoming the president elect of the US. When the UK leaves the EU, it may also leave Euratom, the EU’s framework for safe nuclear energy. JET was scheduled to run after its scheduled finish date in 2018 due to delays with ITER, but this will now depend on Brexit negotiations and funding changes; and uncertainty over Donald Trump’s future energy policies may cast doubt over the US’s involvement in the project (the US government has also previously suggested eradicating the funding). Whether these shifts in politics and others to come change the direction of fusion will be closely watched by many.
Want to know more about fusion energy? Check out our fusion energy infographic.