A fuel with no greenhouse emissions or radioactive waste that is almost unlimited, sounds too good to be true.

But scientists have taken one more step to make fusion power useful and affordable.

Engineers have designed a concept for a fusion reactor which, when scaled up to the size of a large electrical power plant, would rival costs for a new coal-fired plant with similar electrical output.

Engineers have designed a concept for a fusion reactor (pictured) that, when scaled up to the size of a large electrical power plant, would rival costs for a new coal-fired plant with similar electrical output

Until now no-one has come up with a fusion power plant design – dubbed the ‘holy grail’ of energy generation by many - that would produce fuel cheap enough to outperform systems that use fossil fuels such as coal and natural gas.

Fusion, the process that powers the sun and other stars, entails forging the nuclei of atoms to release energy, as opposed to splitting them, which is fission - the principle behind the atomic bomb and nuclear power.

Engineers from the University of Washington have published their design and analysis findings and will present them at the International Atomic Energy Agency’s Fusion Energy Conference in St. Petersburg, Russia, this week.

‘Right now, this design has the greatest potential of producing economical fusion power of any current concept,’ said Thomas Jarboe, a professor of aeronautics and astronautics at the university.

Other designs, such as the experimental fusion reactor project called Iter (its internals are pictured in a diagram) which is currently being built in France have to be much larger than the university's because they rely on superconducting coils that circle around the outside of the device to provide a similar magnetic field

RECREATING THE SUN'S CORE Nuclear fusion is a process by which the nuclei of deuterium and tritium, both isotopes obtained from hydrogen, are fused together to create heavier particles. In theory, energy generated through fusion would leave no dangerous waste or pollute the atmosphere. And the fuel is found in abundance in seawater, which covers more than two-thirds of the planet. The process requires extreme temperatures and pressure equivalent to those found on our Sun and other active stars. Advertisement

While the idea started as a class project, Professor Jarboe and a doctoral student in reactor design, Derek Sutherland, refined the concept.

The design builds on existing technology and creates a magnetic field within a closed space to hold plasma in place long enough for fusion to occur - allowing the hot plasma to react and burn.

The reactor itself would be largely self-sustaining, meaning it would continuously heat the plasma to maintain thermonuclear conditions.

Heat generated from the reactor would heat up a coolant that is used to spin a turbine and generate electricity, similar to how a typical power reactor works.

Mr Sutherland said: ‘This is a much more elegant solution because the medium in which you generate fusion is the medium in which you’re also driving all the current required to confine it.’

There are several ways to create a magnetic field, which is crucial for keeping a fusion reactor going.

The new design is known as a spheromak, meaning it generates the majority of magnetic fields by driving electrical currents into the plasma itself.

This reduces the amount of required materials and allows researchers to shrink the overall size of the reactor.

Other designs, such as the experimental fusion reactor project called Iter, which is currently being built in France have to be much larger than the UW’s because they rely on superconducting coils that circle around the outside of the device to provide a similar magnetic field.

The researchers estimated the cost of building a fusion reactor power plant using their design compared to building a coal power plant (stock image). Mr Sutherland said: ‘If we do invest in this type of fusion, we could be rewarded because the commercial reactor unit already looks economical. It’s very exciting'

When compared with the fusion reactor concept in France, the new design is much less expensive at roughly one tenth of the cost of Iter and would produce five times as much energy.

The researchers estimated the cost of building a fusion reactor power plant using their design compared to building a coal power plant.

They explained that building a fusion power plant producing 1 gigawatt (1 billion watts) of power would cost $2.7 billion (£1.7 billion), while a coal plant of the same output would cost $2.8 billion (£1.8 billion), according to their analysis.

Mr Sutherland said: ‘If we do invest in this type of fusion, we could be rewarded because the commercial reactor unit already looks economical. It’s very exciting.’

The concept that has been created is around one-tenth the size and power output of a final product, which will take years to develop. IT was funded by the US Department of Energy.