Foghorn aimed to reduce emissions of carbon dioxide into the atmosphere that contribute to climate change, by developing “sea fuel” – a new type of liquid fuel created from seawater.

The Moonshot

Huge Problem

Transportation generates 14% of global greenhouse emissions

The increased greenhouse gases in our atmosphere trap in heat and warm our planet. Globally, nearly 97 percent of the transportation-related greenhouse gas emissions come from direct combustion of fossil fuels in vehicles like cars, trucks and planes.

Radical Solution

“Sea fuel” – a carbon-neutral liquid fuel alternative

What if we could extract carbon dioxide from seawater to produce a new liquid fuel with the same advantages of fuels used today, without putting more carbon dioxide into the atmosphere?

Breakthrough Technology

Electrochemical processes to create hydrocarbons from seawater

Seawater contains hydrogen and oxygen (water is H2O), but also carbon dioxide that has been naturally absorbed over time from the earth’s atmosphere. Electrochemical processes could pull the existing carbon and hydrogen out of seawater, which could then be combined to make hydrocarbons for liquid fuel: a clean “sea fuel”.

The Investigation

In early 2014, we collaborated with PARC to complete our first task: build an end-to-end prototype of the system. It worked! Using new chemical processes, the prototype successfully created methanol out of seawater. But proving that the technology works was just the first part of the problem. Real world costs such as labor, taxes, shipping and others can be surprising. We would need to be convinced that we could make fuel from seawater cost competitive with gasoline to proceed.

The critical next step for our investigation: create as accurate a cost model as possible. Early theoretical models based on academic sources suggested that it would be possible to make this fuel for somewhere between $5-10 per gasoline gallon equivalent or (gge). So when we began our work, we set our cost target at $8 per gge and outlined a path to $5 per gge within five years, which would make our sea fuel cost competitive in expensive markets like the Nordic countries.

Was it possible to extract carbon dioxide cheaply from seawater?

After observing our initial system prototype, we were concerned by salt water mineral deposits that had accumulated on the membranes inside the system during the carbon dioxide extraction process. These membranes were one of the most critical parts of the system, so having to replace them frequently would impact the cost of production. So we built several prototypes to improve our methods and found a way to preserve the membranes in the process. With this technical progress, we felt optimistic to continue.

Could our system produce a cost-competitive fuel?

While refining our prototype, we started to think about how we could scale the system. We knew we’d need to pump a lot of seawater, so we began learning as much as we could about desalination plants who already handle this challenge. It turns out that pumping seawater at scale is expensive. So to keep our sea fuel costs down, we’d need to make other processes in the system more efficient.

By August 2015, we saw a path to $8-16 per gge, but still needed to find a cheap source of hydrogen.

Could we find a cheap source of hydrogen?

We investigated existing hydrogen creation processes, but discarded those that were either cost prohibitive or would emit carbon dioxide as a byproduct. That led us to a promising new technique called solid oxide electrolyzer cell (SOEC) which uses electricity to break apart steam into hydrogen and oxygen. After meeting with experts in the field, we realized it could take more than 5 years and significant capital investment to become a viable, cheap source of hydrogen. That time horizon isn’t a fit for X.

Flipping the Kill Switch

In January 2016, after 2 years of work, we decided to end our investigation. The cost models sent a clear message: sea fuel wasn’t worth pursuing at the current and projected cost of hydrogen.

Along the way, we learned that it’s probably possible to build sea fuel production system that yields $15 per gge in the next few years. That’s not a highly unreasonable production price for fuel. But the hydrogen production process would need to advance significantly before sea fuel could become truly cost competitive with today’s hydrocarbon liquid fuels. Hydrogen production is a research endeavor that is far outside X’s core competencies in rapid prototyping and product development, so we determined this wasn’t a reasonable risk for X to take. Instead, we’re directing our resources at more promising technologies for now.

You can find our research and analysis in the International Journal of Greenhouse Gas Control here and here. We hope builders, inventors, scientists, and engineers around the world, from various industries and backgrounds, can review our work and use it to find new ideas that could bring this moonshot of carbon-neutral fuel to the world.

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