Linear generator running on hydrogen, ammonia

Mainspring Energy has adapted its linear generators so they can run on hydrogen or ammonia fuel, on top of widely available fuels such as natural gas and biogas.

“The generator has passed key tests to directly run 100% hydrogen and 100% ammonia fuels at high efficiencies,” said company spokesperson Maria Amundson. “It may be used to displace intensive diesel generators at data centers, hospitals, grocery stores, and in behind-the-meter applications as well as in large grids and microgrids.”

The company says the linear generator can ramp up and down quickly via solar. It also has the ability to dynamically switch between different kinds of fuels.

In order to make the generator work with hydrogen and ammonia, the company created a new design incorporating new power electronics.

“Our generator automatically adapts to the composition of incoming fuels and responds accordingly with precise control of the reaction to maximize efficiency,” said Amundson.

Mainspring Energy offers the solution in 230 kW packages with two linear generator cores. It claims the generators can be linked with similar devices to reach a capacity of up to 15 MW.

“Projects greater than 1.5 MW can be optimally designed with the use of external inverters,” it sad. Each generator measures 20.5 meters x 8.5 meters x 9.5 meters, weighs 20 tons, and can operate at temperatures ranging from -20 C to 50 C.

The generator, like its previous version running on natural gas or biogas, uses a low-temperature reaction of air and fuel to drive magnets through copper coils to produce electricity. The electrically controlled linear motion of oscillators embedded in the system compresses the fuel and air mixture until the mixture reacts uniformly and instantaneously without a flame or burning.

This reaction drives the two oscillators carrying magnets through copper coils and produces electricity through linear motion. Outer springs are then compressed to return the oscillators for the next cycle.

She claimed that the generator is particularly efficient when it runs on ammonia.

“When running on ammonia, Mainspring can use off-the-shelf technology that is currently deployed with gas turbines to yield low nitrogen oxide (NOx) emissions and can meet any permitting standard,” she said. “Our ability to run directly on pure ammonia is a significant performance and cost advantage for customers because it avoids an energy loss of up to 30% to convert it back to hydrogen, depending on the application. It also completely eliminates the need for additional fuel and fuel generation equipment such as fuel cells, which would be needed to convert ammonia back to hydrogen.”