A fusion start-up has managed to generate temperatures hotter than the core of the Sun with a “unique” approach it claims can deliver limitless clean power at a fraction of the cost and complexity of competitors.
US-based Zap Energy claims its fusion concept has now joined the “rarefied ranks” of technologies that have generated thermal fusion plasma with electron temperatures hotter than 10 million degrees Celsius.
Zap said in a press release on Tuesday that its unique approach, known as a sheared-flow-stabilised Z pinch, has now blasted past this milestone – achieving temperatures roughly equivalent to 11 to 37 million degrees Celsius.
“This feat is a key hurdle for fusion systems,” said Zap, claiming that its Z pinch reactor is the “simplest, smallest and lowest cost device to have achieved it.”
Ben Levitt, vice president of research and development at Zap “These are meticulous, unequivocal measurements, yet made on a device of incredibly modest scale by traditional fusion standards.”
“We can now stand shoulder to shoulder with some of the world’s pre-eminent fusion devices, but with great efficiency, and at a fraction of the complexity and cost.”
Fusion uses the same process that generates light and heat from stars, fusing hydrogen and other light elements to release huge amounts of power that pioneers in the sector hope to tap for unlimited zero-carbon electricity, sometimes referred to as the 'Holy Grail' of the energy transition.
Seattle-based Zap was spun out of the US Department of Energy’s Advanced Research Projects Agency – Energy.
Its backers include Bill Gates’ energy innovation fund Breakthrough Energy Ventures and Shell Ventures, which handed Zap $160m in a Series C funding round in 2022.
Zap says that, unlike tokamaks and stellarators, the two mainstream fusion approaches that have been the focus of the majority of fusion research in recent decades, its technology “does not require expensive and complex superconducting magnets or powerful lasers.”
“Zap tech is orders of magnitude less expensive and quicker to build than other devices, allowing us to iterate rapidly and produce the cheapest thermal fusion neutrons out there,” said the start-up’s CEO and co-founder Benj Conway.
To generate a fusion reaction you first need plasma. Zap’s fusion device first puffs gas into a chamber. An intense pulse of energy ionises the gas into what becomes a two-foot filament of plasma, which carries an electrical current more than 10 times stronger than a bolt of lightning.
Next, a wave of fusion reactions transforms the deuterium and tritium fuel into high-energy helium and neutrons, which can be captured to generate heat and electricity.
This approach, known as Z-pinch fusion, was tested as far back as the 1950s, but Zap said researchers were “stymied by how quickly the plasmas fizzled out.”
Zap says it has solved the problem through sheared-flow stabilisation — a plasma physics innovation that can theoretically extend the lifetime of a Z-pinched plasma almost indefinitely.
“The dynamics are a wonderful balancing act of plasma physics,” said Levitt.
“As we climb to higher and higher plasma currents, we optimize the sweet spot where the temperature, density and lifetime of the Z pinch align to form a stable, high-performance fusing plasma.”
Zap's choice of fuel, tritium, is wildly expensive – reportedly $30,000 a gram in 2022, almost as precious as a diamond. Zap, however, plans to generate the isotope within its reactor using neutrons cast off by fusion reactions.
