Hydrogen and Carbon Capture Together at Last

Planetary Hydrogen stores carbon while it generates hydrogen with renewable electricity.

Mike Kelland in lab
Mike Kelland in Lab.

Planetary Hydrogen

Treehugger has often been skeptical of two "silver bullets" for the climate crisis: the hydrogen economy and carbon capture and storage (CCS). However, a company in Dartmouth, Nova Scotia called Planetary Hydrogen mashes the two together in a double-barrelled approach that makes a lot of sense.

In the pre-industrial natural carbon cycles, most atmospheric carbon dioxide (CO2) was absorbed by plants, but about a quarter of it was absorbed by the ocean in a process where CO2 in rainwater dissolves calcium and other minerals in rocks and washes into the ocean. This is converted by animals into calcium carbonate for their shells, which when pressed together over millions of years stores CO2 in limestone. Needless to say, such a process happens in geological time, millions of years, a very slow carbon cycle. However, now we are putting so much CO2 into the atmosphere – 7% of it by undoing this process by cooking limestone to get the CO2 back out of it and making cement – that the ocean can't keep up and is acidifying.

This is all a very slow process, and as Planetary Hydrogen CEO Mike Kelland notes, "we don't have 100,000 years to fix this problem." His company takes fossil-fuel-free electricity from wind, solar, or water power and uses an electrolyzer to separate water into hydrogen and oxygen, building on the work of Dr. Greg Rau, who has written a number of papers on the subject going back to the 1990s. Planetary Hydrogen adds a little something to the mix, turning it into negative emissions hydrogen or NE H2.

"Our innovation is that by adding a mineral salt, we force the electrolysis cell to also create an atmosphere-scrubbing compound called mineral hydroxide as a waste product. That hydroxide actively binds with carbon dioxide, producing an “ocean antacid” very similar to baking soda. The net effect is the direct capture and storage of CO2 while producing valuable pure hydrogen. The system can consume as much as 40kg of CO2 and permanently stores it for every 1kg of hydrogen it produces."

This is very different from the carbon capture and storage processes that we usually see, where one of the big problems is what to do with the CO2. Here, sodium hydroxide is produced in the electrolyzer, which combines with CO2 in seawater to produce sodium bicarbonate, It's also literally just a drop in the ocean. Planetary Hydrogen continues:

"This system accelerates “The Earth’s Natural Thermostat” which is the geological process that removes excess CO2 from the atmosphere via rock weathering that is otherwise very slow and inefficient. Excess CO2 in the atmosphere acidifies rainwater that on contact with alkaline minerals (exposed on much of the Earth’s land surface), dissolves the rock and consumes CO2, forming dissolved mineral bicarbonate which is washed into the ocean. This process is the reason that some 90% of the Earth’s surface carbon is in this form as seawater bicarbonate." 

Producing hydrogen through electrolysis is not very efficient, and a report from S&P Global says it has to drop in cost by over 50% to be a viable alternative to hydrogen made from fossil fuels. That's where Planetary Hydrogen comes into its own; its hydrogen is seriously carbon negative, which can generate valuable carbon credits. This is not just CO2 emissions avoided by using hydrogen, it's CO2 that is seriously sequestered in the sea. In fact, Mike Kelland tells Treehugger that it is really more of a carbon storage business than a hydrogen business, using the Gillette analogy: "Hydrogen is the razor but carbon is the blade."

In his study, The Global Potential for Converting Renewable Electricity to Negative-CO2-Emissions Hydrogen, Rau concludes:

"With the potential to utilize a broad range of renewable energy sources, NE H2 significantly expands global, negative-emissions energy generation potential, assuming greatly increased H2 and negative-emissions markets can be realized. It could also be useful in reducing the carbon footprint of conventional fuel and electricity production and of energy storage. It achieves these features by merging three separate technologies: renewable electricity, saline water electrolysis, and enhanced mineral weathering."

That is why this is all so interesting. Whether or not one thinks there will ever be a hydrogen economy, vast quantities of the stuff are used for making ammonia and it could clean up steelmaking. The price of renewable energy is dropping so quickly that one of the proposed ways of dealing with intermittency is to overbuild the system, so there may well be lots of surplus renewable energy around, particularly in windy places like Nova Scotia. And of course, storing 40 kilograms of CO2 for every kilogram of hydrogen produced while deacidifying the ocean is pretty remarkable.

Next to growing trees, growing the stuff of seashells seems like a pretty good place to store carbon.

Kelland tells Treehugger that they have a long way to go before commercialization; that's why they moved the company to Nova Scotia, where researchers at Dalhousie University can work with them to test its impact on the ocean and local sea life, But this is one to watch.

View Article Sources
  1. "Cement Produces More Pollution Than All the Trucks in the World." Bloombery, 2019.

  2. Caldeira, Ken, and Greg H. Rau. "Accelerating Carbonate Dissolution to Sequester Carbon Dioxide in the Ocean: Geochemical Implications." Geophysical Research Letters, vol. 27, no. 2, 2000, pp. 225-228, doi:10.1029/1999gl002364

  3. Edwardes-Evans, Henry. "Green hydrogen costs need to fall over 50% to be viable: S&P Global Ratings." S&P Global, 2020.

  4. Rau, Greg H., et al. "The Global Potential For Converting Renewable Electricity To Negative-CO2-Emissions Hydrogen." Nature Climate Change, vol. 8, no. 7, 2018, pp. 621-625, doi:10.1038/s41558-018-0203-0