What set of topics involve the following: Billionaires. High tech. Clean energy. Negative cash flow. Electric power. Government subsidies.

Solar energy? Wind power? Electric vehicles? All correct, but now we can add another one to the list: Nuclear fusion, which we all remember from high-school science class, is the process of how stars generate light and heat by smashing atoms together. It is the opposite of fission, where heavy isotopes are split apart.

Fusion works by forging lighter elements, such as hydrogen, together to form heavier ones, such as helium. This process liberates vast amounts of energy. However, fusion produces energy only at temperatures of hundreds of millions of degrees – hotter than any solid material can withstand. To get around this, scientists use powerful magnetic fields to hold the plasma in place to prevent it from coming into contact with any part of the containment vessel.

The promise of fusion is huge: the fuel source (water) is inexhaustible and ubiquitous, and the reaction does not create greenhouse gases or produce radioactive waste of the sort made by conventional nuclear fission reactors. The problem is that every fusion experiment so far has used more energy to create the magnetic field than it produces - making it useless as a form of power generation.

However, nearly a dozen startups are designing new kinds of reactors and power plants they say can come online long before and far more cheaply – even if the requisite technology isn’t there yet.

Commonwealth Fusion Systems is a MIT spin-off tied to the university’s Plasma Science and Fusion Center and partially funded by ENI. Commonwealth recently announced that they think they can put fusion power on the grid within 15 years. They are using new superconducting materials – a steel tape coated with a compound called yttrium-barium-copper oxide, or YBCO – to allow scientists to produce smaller, more powerful magnets, which reduces the amount of energy needed to get the fusion reaction off the ground.

The planned reactor is set to be far smaller – about 1/65th of the volume – than that of the International Thermonuclear Experimental Reactor (ITER) project in southern France, which draws in India, Japan, Russia, South Korea and the US and is expected to start testing in 2025. The UK, Germany and China are also pursuing nuclear fusion research on their own.
 
General Fusion, a venture backed by Amazon founder Jeff Bezos, wants to build a spherical reactor in which hydrogen plasma would be surrounded by liquid metal and compressed with pistons to cause a burst of fusion. The burst heats the liquid metal to generate steam and spin a turbine generator, producing massive amounts of electricity.

Silicon Valley is also involved in these efforts as supercomputing has helped to advance the state of fusion technology over the past 20 years by allowing researchers to precisely model the behavior of plasma under different conditions.

Until recently economies have always moved from low-density (btu/lb), high cost ($/btu) energy sources – think livestock to pull plows – to high-density, low-cost energy sources such as coal, petroleum and nuclear. The main fuel for fission, Uranium-235, has 2 million times the energy per pound that oil does; fusion may deliver up to seven times that or more.

The current emphasis on low-density solar and wind power has reversed that trend, but cost-efficiency will always be a powerful factor in energy use. And if nuclear fusion can be made to work, it will transform the power sector in terms of its reliance on coal, gas, nuclear fission and renewables.

Change happens slowly, until it happens fast.