4 ms·

> it only makes sense to spend energy on sucking CO2 out of the atmosphere, once you've already de-carbonised everything which you possibly can. Except possibl

by _rpd 7y ago

> it only makes sense to spend energy on sucking CO2 out of the atmosphere, once you've already de-carbonised everything which you possibly can. Except possibly when energy prices are negative due to wind and solar intermittency - although that is also a signal that you need more storage in the grid, additional storage may not be economic for some reason.

strainer 7y ago
Some captured CO2 might be used with cheap electricity to make carbon neutral fuel - which is of course a form of stored energy itself. A pilot project in Germany is doing this[1]: > The green hydrogen will be combined with carbon dioxide captured from the cement plant to produce synthetic methanol, which would then be refined into carbon-neutral synthetic kerosene (ie, aviation fuel), for use at the nearby Hamburg airport. The airport is hoping that 5% of all fuel used there will be carbon-neutral by 2025. [1] https://www.rechargenews.com/transition/offshore-wind-to-power-giant-green-hydrogen-carbon-neutral-aviation-fuel-plant/2-1-696907 https://www.rechargenews.com/transition/offshore-wind-to-pow...
gwbas1c 7y ago
Honestly, I suspect that long-term storage will be inefficient for a long time. For example, batteries exceed 90% efficiency for storage, but they are only cost effective for day-to-day storage. (Charge when the sun is out, discharge at night.) In contrast, charge during long summer days, and discharge during shorter winter days will probably be lower efficiency at first. For example, generating hydrogen by electrolysis is about 75% efficient (https://en.wikipedia.org/wiki/Hydrogen_production#Electrolysis https://en.wikipedia.org/wiki/Hydrogen_production#Electrolys...), and then pressurizing it will also consume energy. This means it may be more cost efficient to extract CO2 from the atmosphere as "storage" and then burn natural gas... At least until we find a better way to store energy than hydrogen!

by _rpd 7y ago

strainer 7y ago

Some captured CO2 might be used with cheap electricity to make carbon neutral fuel - which is of course a form of stored energy itself. A pilot project in Germany is doing this[1]: > The green hydrogen will be combined with carbon dioxide captured from the cement plant to produce synthetic methanol, which would then be refined into carbon-neutral synthetic kerosene (ie, aviation fuel), for use at the nearby Hamburg airport. The airport is hoping that 5% of all fuel used there will be carbon-neutral by 2025. [1] https://www.rechargenews.com/transition/offshore-wind-to-power-giant-green-hydrogen-carbon-neutral-aviation-fuel-plant/2-1-696907 https://www.rechargenews.com/transition/offshore-wind-to-pow...

gwbas1c 7y ago

Honestly, I suspect that long-term storage will be inefficient for a long time. For example, batteries exceed 90% efficiency for storage, but they are only cost effective for day-to-day storage. (Charge when the sun is out, discharge at night.) In contrast, charge during long summer days, and discharge during shorter winter days will probably be lower efficiency at first. For example, generating hydrogen by electrolysis is about 75% efficient (https://en.wikipedia.org/wiki/Hydrogen_production#Electrolysis https://en.wikipedia.org/wiki/Hydrogen_production#Electrolys...), and then pressurizing it will also consume energy. This means it may be more cost efficient to extract CO2 from the atmosphere as "storage" and then burn natural gas... At least until we find a better way to store energy than hydrogen!