Arbor’s ‘vegetarian rocket engine’ power plant is actually an omnivore

Two years ago, former SpaceX engineers used rocket tech to develop a power plant capable of removing carbon dioxide from the atmosphere, with a small asterisk. To draw down CO₂, it burned plant waste, making it a sort of “vegetarian rocket engine” for the grid.

This week, Arbor Energy said it had raised a $55 million Series A led by Lowercarbon Capital and Voyager Ventures on the heels of a partial pivot. Its power plant, rather than sticking to a strict vegetarian diet, is going to be more of an omnivore, capable of burning natural gas in addition to biomass. 

The shift happened this year as electricity demand from data centers has boomed. The existing design was fully capable of powering AI servers, but its reach would be limited by sources of wood and agricultural waste. Natural gas is more widely available.

Arbor still plans to capture CO₂ from the power plant, which uses oxy-combustion, which transforms hydrocarbons into syngas and then burns it in the presence of pure oxygen. The result is CO₂ that doesn’t need much preparation for sequestration.

Because of tax credits, storing the CO₂ will be cheaper than dumping the pollutant into the atmosphere, Arbor spokesperson Patrick Mahoney told TechCrunch. The company does not plan to sell its technology to businesses that don’t plan on capturing the carbon for use or sequestration, he said.

But waste CO₂ isn’t the only climate consideration when it comes to burning natural gas. The main component of natural gas is methane, which is a potent greenhouse gas that generates 84 times more warming than carbon dioxide over 20 years. 

Because of that, any leaks in the natural gas supply chain can have an outsized effect on the climate impact of a natural gas-fired power plant. Leakage rates as low as 0.2% mean the carbon footprint of a gas-fired power plant could be the same as a coal plant, according to recent research. The U.S. government has estimated that leakage rates throughout the oil and gas supply chain to be around 1%, while satellite measurements show rates of about 1.6% across the U.S.

Arbor said it is working with natural gas providers that are certified to have low leakage rates, with a goal of getting the climate impact of one kilowatt of electricity it generates below 100 grams (about a quarter of a pound). 

The startup confirmed that it is still in the process of building a power plant in Louisiana that will burn biomass. That plant is being funded in part by a $41 million deal with Frontier, the advanced market commitment backed by Stripe, Google, and others. Under that agreement, Arbor must remove 116,000 tons of carbon dioxide by 2030.