You may have heard about cold fusion, the idea that atoms can be fused together without using any significant heat or other type of energy and yet producing a great deal of energy. This philosopher’s stone has been the object of the quest of many a modern-day alchemist, so we shall leave it to them.
Hot fusion, however, is real. It’s what happens inside the sun and other stars. Nuclei of atoms crash into each other at great speed, resulting in fusion and a great deal more energy released. Research and development into fusion energy is trying to create similar reactions here on Earth at over 100 million degrees Celsius.
The opposite of nuclear fission
Fusion energy, in a way, is the opposite of what we conventionally call nuclear energy – although fusion energy also deals with the nucleus of atoms. In current nuclear power plants, the energy comes from splitting the atom. Fusion, as the name suggests, produces energy not by breaking atoms apart, but by fusing them together.
The real difference comes from the kind of elements involved in these processes. What we know as nuclear energy requires elements with big, heavy atoms like uranium or plutonium that can be split into smaller atoms. However, uranium, plutonium, and their fission products are radioactive, which means that when they decay they emit ionising radiation, which in certain circumstances might be dangerous to humans.
Fusion energy instead is based on combining two lightweight atoms – usually hydrogen. When two hydrogen atoms fuse, they create helium. So not only does fusion energy rely on the most abundant element in the universe, its byproduct can be easily used for medical purposes, or to blow up balloons.
Try pushing two magnets together
How do you fuse two atoms? The challenge comes from the fact that the nucleus of an atom contains positively charged protons and neutral neutrons, as you will surely recall from your physics class. Therefore, the nucleus of an atom will always carry a positive charge. Trying to combine it with another one with a positive charge is like trying to push two magnets towards each other. They will resist. This is why fusion energy uses the lightest atoms possible. But it is still very hard.
Inside the sun, fusion occurs because the immense gravity draws atoms together, creating extreme density and enormous heat, which makes the atoms collide with each other at great speed. The force of gravity is much weaker on Earth, because of the relatively small size of this planet, and the temperature – despite global warming – is nowhere close to the heat of the sun. So how can we create similar conditions here for fusion to occur?
Hotter than the sun
The answer is fairly obvious. To make up for our lower gravity, you simply have to create a temperature hotter than the sun. Six to ten times hotter, up to 150 million degrees Celsius. Here on Earth this tremendous heat will create the conditions to allow the hydrogen atoms to bump into each other, resulting in fusion and generating even more energy. Sounds easy? There are quite a few details that need to be ironed out.
First issue: where could you create such a temperature, so that the heated substance wouldn’t destroy everything it touches? Again, the solution is simple: don’t allow it to come into contact with anything. To achieve this, Russian scientists in the middle of the 20th century developed the tokamak, a chamber the shape of a hollow doughnut, surrounded by powerful magnets.
Inside this chamber, the hydrogen gas is heated to an extremely high temperature and transformed into a plasma state. The plasma state is one of the four fundamental states of matter, in which the gaseous substance becomes ionised – because electrons orbiting the atomic nuclei are stripped away. The ionised matter is electrically conductive and therefore the magnetic fields can dominate the behaviour of the matter. That is where the magnets come in. Magnets can keep this electrically conductive substance from approaching the tokamak’s walls, hovering above it. Inside the plasma, the conditions are suitable for the atoms to bump into each other and to fuse, releasing energy.
The world’s largest experimental tokamak nuclear fusion reactor – called ITER – is under construction in France, to prove the feasibility of thermonuclear fusion as a large-scale and carbon-free source of energy. ITER is an international research and engineering megaproject involving the European Union, China, India, Japan, South Korea, Russia and the US. If successful, the facility will turn 50 MW of power inserted into the system – to initially heat the plasma – into fusion power output of 500 MW.
A lot of doughnut
The ITER reactor will be huge:
- the ITER tokamak will be as heavy as three Eiffel Towers;
- the structure of the 1 000-tonne electromagnet in the centre of the machine must be strong enough to contain a force equivalent to twice the thrust of the Space Shuttle at take-off (60 meganewtons, or over 6 000 tonnes of force);
- there will be 18 D-shaped electromagnets around the doughnut-shaped tokamak chamber, each of them 17 metres high and 9 metres wide, weighing 310 tonnes, the approximate weight of a fully loaded Boeing 747-300 aeroplane.
But how could we get that enormous energy out of the doughnut and safely channel it into our homes as electricity? This is done via the main chamber wall and a region called the divertor, positioned at the bottom of the tokamak. The divertor controls the exhaust of heat, waste gas and impurities from the reactor and withstands the highest surface heat loads. The surface of the divertor is covered by tungsten, the metal with the highest melting point (3422°C).
In 2019, with the backing of the European Fund for Strategic Investments, the European Investment Bank signed a €250 million loan to the Italian research agency ENEA to help build the divertor and tokamak test facility. The plant will test various alternatives to exhaust the huge amount of heat flowing into the divertor component of a nuclear fusion reactor.
A glorified steam turbine
Researchers continue to look for alternatives, but as it stands now the whole process of transitioning the heat to electric power then becomes rather old-fashioned. The heat received by the plasma-facing wall and the divertor will be used to turn water into steam, which will drive a steam turbine. The turbine is connected to a generator that produces the electricity to be fed into a grid.
“The scientific advances towards fusion energy are not likely to occur like the apple falling on Newton’s head,” says Istvan Szabo, a senior engineer in the European Investment Bank’s energy security division. “You need many more resources.”
Szabo concedes it is possible that tomorrow someone will come up with a completely different solution to harness fusion energy, or a different answer to the need for sustainable energy to power us into the future. “There are other ideas to compress matter and fuse atoms. For example to use lasers or mechanical compression. And maybe someone will one day solve cold fusion,” Szabo says. “But testing these will all require immense resources. Thermonuclear fusion is furthest along the research and development phase. It offers the most hope.”
Investment to power energy
So we’re getting warmer with the quest for fusion energy, but fusion power is just one of several innovative energy projects that the EIB is financing.
The EIB invested more than €30 million in junior and senior shares of the responsAbility Access to Clean Power Fund. The fund is expected to finance companies offering pay-as-you-go solar lanterns and other off-grid solar power systems for homes and businesses, mostly in sub-Saharan Africa and Southeast Asia. These systems allow low-income families, for example, to run small refrigerators and other appliances. They can pay for the solar power system in small instalments, while the fund finances the provider for the upfront cost of purchasing the system.
Due to the high risk of the investments, the fund has several layers of shares. The most risky layer is the junior share level in which the EIB invested. The purchase of the junior shares thereby reduces the risk of the fund for other investors who buy senior shares. In this way, the EIB’s involvement attracts significant private capital to the fund. Over the lifetime of the fund, clean power is expected to be provided to more than 150 million people.
The EIB also invested €50 million, under the European Commission-supported InnovFin, in an equity fund targeting innovations that could significantly reduce greenhouse gas emissions. Other investors in this fund, called the Breakthrough Energy Ventures Europe, include Bill Gates and a number of other ultra-high net worth individuals.
The connection between these varied projects: they’re making the future more climate friendly.