An acquaintance recently posted a picture of a retail hydrogen pump in Sacramento on social media. The solitary pump, lonely in its sea of asphalt under a suitably gloomy sky, was charging $16.85 USD per kilogram of hydrogen.
Why is that important? Well, a kilogram of hydrogen is the energy equivalent of a gallon of gas. Hydrogen fuel cells are about three times as efficient at converting hydrogen to energy as internal combustion engines are at turning gasoline into energy, so you go about three times as far on a kilogram of hydrogen despite it having the same energy. The Toyota Mirai gets about 66 miles per gallon out of its 5 kg fuel tank.
So really, you are paying about $5.50 to travel the same distance as you could with a $2.50 gallon of gasoline. Hmmm… in a car that costs a lot more than an internal combustion car too.
That might get better sometime, but maybe not. The best resource I found recently when structuring out an end-to-end air-to-fuel system to show why that’s such a poor idea, especially when fed with natural gas as Carbon Engineering does, is that mass production of clean hydrogen in the best case might get down to $5.00 per kg. That’s just the generation cost. That’s not storage, distribution, or markup, and is not the price a consumer would pay.
And hydrogen fuel pumps cost a million or two for a couple and more for the storage tanks. They are much more expensive than gas pumps, so hydrogen stations have to mark up the hydrogen a lot more than gas stations have to mark up the gas.
And those hydrogen stations don’t exist. They all have to be built on somebody’s nickel.
Meanwhile, making clean hydrogen is energy intensive and you throw away a lot of the energy. Let’s assume they get 10 MWh of electricity from a wind farm. Then they convert water to hydrogen and oxygen with the electricity. High-efficiency PEM electrolysis is about 80% efficient (projected to rise to a theoretical peak of 86%). That takes about 50 kWh per kilogram, so you have a couple of hundred kilograms of hydrogen.
You’ve thrown away 20% of the electricity and are left with 8 MWh embodied in the hydrogen.
Then you compress it, store it, ship it, and pump it. All of those things take energy. Let’s say another 10%. So now you have about 8 MWh in the 200 kg of hydrogen that you have spent 11 MWh on far.
And then you put it in a Toyota Mirai at its best case 60% efficiency and throw away another 40%. That means you get 4.8 MWh of energy out of the 11 MWh you’ve spent. Those 200 kg will allow a Toyota Mirai to drive about about 13,000 miles. Let’s be nice and say the retail price of hydrogen gets down to $10 per kg. That will cost you $2,000 to drive those 13,000 miles.
What if you put that 11 MWh in to a Tesla Model S P100D? Well, that car travels about 100 miles for every 30 kWh of electricity you feed it. That means 11 MWh will allow a Tesla Model S to drive about 37,000 miles. That’s about three times as far for the same energy input. And the average cost of electricity in the USA (not the night time cost when you actually charge) is 12 cents per kWh, so those 11 MWh will only cost you about $1,300.
Just to finish this off, the gas car at 28 miles per gallon and 200 gallons will travel about 5,600 miles at a cost of about $500.
The hydrogen-powered Mirai (if you could buy one where you are and if there were hydrogen pumps where you wanted to go, and neither of those things are true) would cost you about four times what just using the electricity would cost and almost twice what just driving a gas car would cost (and hydrogen cars are expensive of course).
Of course, this is the nicest possible way of making hydrogen. Most of it actually comes from steam reformation of natural gas, which has a CO2 debt of its own. The source I quickly found for steam reformation of hydrogen indicates that industrial processes emit 25,808 kgs of CO2 for every 2,551 kgs of hydrogen produced. As the authors from the Gas Research Division, Research Institute of Petroleum note: “In most cases CO2 is purged to the atmosphere because of its useless and harmful nature.“ So that’s not good. What does that look like over a year?
Gasoline produces about 9.1 kg of CO2 for every gallon. Wind energy produces about 8 kg per MWh full lifecycle including all mining, refinement, manufacturing, distribution, construction, operation and decommissioning (and that’s getting better as more of those elements decarbonize).
hydrogen from steam reformation of natural gas is still better than burning gasoline, but that’s still a couple of tons of CO2 from the hydrogen process. And then you look at the wind energy (or solar) going into a Tesla battery and you say, wait a minute. Is that right? Would it really be that much better for the planet to drive a Tesla instead? And that much cheaper too?
Yes and yes.
Even if you just plugged into the wall in California, you’d still only be around 1,200 kg of CO2 per year and improving annually. CAISO just announced that California exceeded 100% of net demand from carbon-neutral electricity sources (wind, solar, hydro, and nuclear) for a bit over an hour on April 21, 2019. There are provisos on that, in that it was a low-demand period during the shoulder season, but that was 17 GW of low-carbon electricity pumping through the wires of California. If you’d been recharging your Tesla then, you would have been averaging about 12 kg CO2 per MWh, and you’d be under 50 kg CO2 for the year.
Gas stations make a couple of grand a week on gas typically, running about 3% profit margin on gasoline. Hydrogen pumps and tanks cost millions. Gas stations in cities are a dying breed because the only way for land that valuable to pay for itself is to build upward, and refueling stations with highly flammable substances require their own, single-story footprint. There’s no way to square that circle.
There are other reasons, but this is the reality of hydrogen for cars. It’s a dumb idea economically for individuals and it’s a dumb idea for the environment too.