4 ms·

In case anyone is curious as to how bio-gassification compares to electrolysis (or a hybrid process), I found this 2009 paper [1] that sums it up decently (at l

In case anyone is curious as to how bio-gassification compares to electrolysis (or a hybrid process), I found this 2009 paper [1] that sums it up decently (at least with the technology available at the time): (Note: SEK := Swedish Krone; currently ~$0.11USD and was roughly the same in 2009) Abstract: "An integrated system for the production of hydrogen by gasification of biomass and electrolysis of water has been designed and cost estimated. The electrolyser provides part of the hydrogen product as well as the oxygen required for the oxygen blown gasifier. The production cost was estimated to 39 SEK/kg H2 at an annual production rate of 15 000 ton, assuming 10% interest rate and an economic lifetime of 15 years. Employing gasification only to produce the same amount of hydrogen, leads to a cost figure of 37 SEK/kg H2, and for an electrolyser only a production cost of 41 SEK/kg H2. The distribution of capital and operating cost is quite different for the three options and a sensitivity analyses was performed for all of these. However, the lowest cost hydrogen produced with either method is at least twice as expensive as hydrogen from natural gas steam reforming." In addition to a dollar-to-dollar comparison, however, I think a Carbon-to-Carnon byproduct comparison is also warranted. If you don't have to pay for geo-sequestration (or the messy supply of grass compared to piped in water), is the small cost increase of electrolysis over bio-gas more than compensated for? As an H2 advocate myself (as an industrial transportation battery alternative), actively looking to boost H2 fuel supply infrastructure, I would be interested to hear from Chimere (OP co-founder) on this point. I ask, because I don't know the answer. 1.) https://www.sciencedirect.com/science/article/pii/S0360319908014481 https://www.sciencedirect.com/science/article/pii/S036031990...

chimere 8y ago
Interesting question - I'm not sure I know the answer but happy to speculate. Electrolysis certainly is a much tidier process than gasification, but everyone seems to assume it's powered by 100% renewable energy. What incentives exist to make H2 production decarbonize faster than the rest of the electricity grid? I'd expect electrolysis to only be fully carbon-neutral when the rest of the grid is, which will take some time. On the other hand, our process is close to carbon neutral from day one (we've confirmed this with an external life cycle assessment), and will become significantly carbon negative when we begin sequestration. And as I mentioned elsewhere, sequestration is the primary mission and electrolysis is unremarkable at it :]
- mojomark 8y ago
  Thanks for the response! So, my point is that in the bio-gas process, you are generation H2 + CO2 and using some proceeds from H2 sales to sequester the CO2 you produce. However, with electrolysis (from renewable elect. plants), you aren't generating any CO2, so any profit that you spend on Carbon sequestration (from somebody else's process) would be a much more Carbon negative proposition overall. All this depends on the H2 production cost as to which is a mor effective Carbon sequestration scheme, right? In the paper I cite (I convert SEK to $): bio-gas costs ~$4/kg H2 (let's say this produces 5 kg of CO2), and electrolysis ~$4.50/kg H2 (producing 0 kg Carbon). Now say it costs $0.50/kg for CO2 sequestration). In the biogas process, because of the cost to sequester the CO2 byproduct, your actually spending ($0.5×$5)+$4 = $6.50/kg H2 produced just to get Carbon Neutral. However, for electrolysis (without the mess) you're only spending $4 to be Carbon Neutral, and if you want you can spend $2.50 (which you avoided by chosing elect. over gas), to go Carbon negative. These are rough numbers I guessed at based on a little googling. Am I far off on the real numbers? I'm really not trying to be a pain. What you're proposing is still light years better than the greedy bastards reforming natural gas and pocketing 100% of the profits without giving a second thought to the environment. I'm just wondering if there might be a way for you guys to do even more good, more easily.
  - pkrein 8y ago
    The economics you're looking at for biogas and electrolysis look roughly right to me. But our models suggest that thermal gasification of biomass can get down to $1/kg. So then you're looking at $4.50+/kg for electrolysis or $1/kg for gasification... and you can see how all that math changes. Electrolysis also typically costs more than you'd expect as soon as you add the requirement of renewable energy supply. Usually the renewable energy supply is solar, which has a ~30% duty cycle. So 70% of the time your electrolyzer is sitting idle. This crushes your economics and makes solar-powered electrolysis untenable in all of the analyses I've seen. We didn't have any clever ideas for how to change that situation, so after looking at it ~1.5 years ago we decided to look elsewhere.
    - mojomark 8y ago

chimere 8y ago

Interesting question - I'm not sure I know the answer but happy to speculate. Electrolysis certainly is a much tidier process than gasification, but everyone seems to assume it's powered by 100% renewable energy. What incentives exist to make H2 production decarbonize faster than the rest of the electricity grid? I'd expect electrolysis to only be fully carbon-neutral when the rest of the grid is, which will take some time. On the other hand, our process is close to carbon neutral from day one (we've confirmed this with an external life cycle assessment), and will become significantly carbon negative when we begin sequestration. And as I mentioned elsewhere, sequestration is the primary mission and electrolysis is unremarkable at it :]

mojomark 8y ago
Thanks for the response! So, my point is that in the bio-gas process, you are generation H2 + CO2 and using some proceeds from H2 sales to sequester the CO2 you produce. However, with electrolysis (from renewable elect. plants), you aren't generating any CO2, so any profit that you spend on Carbon sequestration (from somebody else's process) would be a much more Carbon negative proposition overall. All this depends on the H2 production cost as to which is a mor effective Carbon sequestration scheme, right? In the paper I cite (I convert SEK to $): bio-gas costs ~$4/kg H2 (let's say this produces 5 kg of CO2), and electrolysis ~$4.50/kg H2 (producing 0 kg Carbon). Now say it costs $0.50/kg for CO2 sequestration). In the biogas process, because of the cost to sequester the CO2 byproduct, your actually spending ($0.5×$5)+$4 = $6.50/kg H2 produced just to get Carbon Neutral. However, for electrolysis (without the mess) you're only spending $4 to be Carbon Neutral, and if you want you can spend $2.50 (which you avoided by chosing elect. over gas), to go Carbon negative. These are rough numbers I guessed at based on a little googling. Am I far off on the real numbers? I'm really not trying to be a pain. What you're proposing is still light years better than the greedy bastards reforming natural gas and pocketing 100% of the profits without giving a second thought to the environment. I'm just wondering if there might be a way for you guys to do even more good, more easily.
- pkrein 8y ago
  The economics you're looking at for biogas and electrolysis look roughly right to me. But our models suggest that thermal gasification of biomass can get down to $1/kg. So then you're looking at $4.50+/kg for electrolysis or $1/kg for gasification... and you can see how all that math changes. Electrolysis also typically costs more than you'd expect as soon as you add the requirement of renewable energy supply. Usually the renewable energy supply is solar, which has a ~30% duty cycle. So 70% of the time your electrolyzer is sitting idle. This crushes your economics and makes solar-powered electrolysis untenable in all of the analyses I've seen. We didn't have any clever ideas for how to change that situation, so after looking at it ~1.5 years ago we decided to look elsewhere.
  - mojomark 8y ago