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These liquid Norbornadiene Photoswitches have an energy storage density of up to .559 MJ/kg.[1] For comparison: Mechanical Flywheel- 0.36–0.5 Lithium-ion bat

These liquid Norbornadiene Photoswitches have an energy storage density of up to .559 MJ/kg.[1] For comparison: Mechanical Flywheel- 0.36–0.5 Lithium-ion battery- 0.36–0.875 etc...[2] [1] https://www.nature.com/articles/s41467-018-04230-8 https://www.nature.com/articles/s41467-018-04230-8 [2] https://en.wikipedia.org/wiki/Energy_density#Energy_densities_of_common_energy_storage_materials https://en.wikipedia.org/wiki/Energy_density#Energy_densitie...

verelo 8y ago
So, it's as good as a "good" flywheel? or as good as a middle of the road lithium-ion battery? That's interesting!
sjburt 8y ago
If so, storing a season's worth of heat might not be so feasible. A home in northern Europe needs about 30,000 MJ, so that would be 53,000 kg of norbornadeine. If the system absorbs energy during the day and releases energy at night, it might work with quite a bit less (maybe only a few hundred kg). It's interesting that the article doesn't suggest that. I wonder if there is a reason that wouldn't work--not enough solar energy in the winter, perhaps?
- jws 8y ago
  Your solar collectors will still be pulling in 1/3 of summer sun in the middle of winter (rough estimate, varies by latitude and weather, void above arctic circle). At the edges of winter you’d even be gaining energy still, so let’s say 40,000kg. That fits in an underground tank typically used by gasoline stations and could be filled by two tank trucks. Sounds doable in the scheme of new house construction, subject to the cost of the chemical of course. But, I have to think that if space is available, increasing the collector area to gather more winter energy and reducing the inventory of chemical and energy would make more sense. In the summer you could sell your saturated chemical to industry and have them replace it with unsaturated to offset your panel cost. Of course now that I have introduced shipping… who wants to live in a shiny reflector farm? Cover industrial buildings and car parks with reflectors, ship or pipe the chemical to houses and have a nicer domestic landscape. I wonder if there are degradation issues? They make a point of being able to store for 18 years which probably only interests survivalists, but make no mention of cycle limits.
  - extrapickles 8y ago
    Assuming the at-scale cost is similar to gasoline, it would cost ~$75k just for that much material. If you assume the useful life is 18 years, you would have to spend >$347/mo on heating/cooling for it to be worth it.
    - jvanderbot 8y ago
      You're suggesting buying pre-charged sun juice? That seems less helpful. TFA suggested you can have much less by recharging it, and did not suggest the fluid expires ever (suggested otherwise, actually). It holds energy for 18 years, but can be used in cycle forever.
- m_eiman 8y ago
  A home in northern Europe needs about 30,000 MJ Really? We live in central Sweden, just outside Gothenburg. According to the estimate from our power company, our house uses about 15,000 MJ per year - and we have a single floor 200 square meter house. It's rated "C" in energy efficiency (which is the minimum rate allowed for new housing now).
  - bjelkeman-again 8y ago
    I live in a house from 1909, with a heat pump (bergvärme). We probably use 18000 kWh for hearing in a year, 64800 MJ, at 190 m2 plus basement. 30000 MJ wouldn’t be enough for us I guess.
beefield 8y ago
Do I calculate right that plain water stores energy around 0.2 MJ/kg when heated by 50 degrees celsius? (Specific heat is 4 J/gK) If I am right, ot feels like it would likely be cheaper to just make seasonal heat storages with water.
- Someone 8y ago
  https://www.ecovat.eu/?lang=en https://www.ecovat.eu/?lang=en aims for water of 90 degrees Celsius (a 70 degree difference with room temperature), and claims heat can be stored with 95% efficiency (possibly exaggerated; the site also says ‘over 90%’) for more than 6 months in a tank 16m deep and 13m in diameter.
  - hinkley 8y ago
    And if it leaks into the groundwater you only have to worry about the anti fouling agents you put into the tank, and anything leaching out of the tank lining.
endymi0n 8y ago
Are you sure they're talking about the same thing? Norbornadiene has a formula of C7H8, while the OP team's molecule is composed of "carbon, hydrogen and nitrogen". But thanks for posting some context on current research anyway!
deleted 8y ago
[deleted]
gus_massa 8y ago
IIUC the good part of these molecules is that the energy storage is very stable. With a flywheel the friction will stop it in a few ¿hours/days? The batteries also discharge too fast to store the energy for months. In other comment, someone else proposed to store the energy in hot water, but it's also difficult to keep the hot water for too long.

verelo 8y ago

So, it's as good as a "good" flywheel? or as good as a middle of the road lithium-ion battery? That's interesting!

sjburt 8y ago

If so, storing a season's worth of heat might not be so feasible. A home in northern Europe needs about 30,000 MJ, so that would be 53,000 kg of norbornadeine. If the system absorbs energy during the day and releases energy at night, it might work with quite a bit less (maybe only a few hundred kg). It's interesting that the article doesn't suggest that. I wonder if there is a reason that wouldn't work--not enough solar energy in the winter, perhaps?

jws 8y ago
Your solar collectors will still be pulling in 1/3 of summer sun in the middle of winter (rough estimate, varies by latitude and weather, void above arctic circle). At the edges of winter you’d even be gaining energy still, so let’s say 40,000kg. That fits in an underground tank typically used by gasoline stations and could be filled by two tank trucks. Sounds doable in the scheme of new house construction, subject to the cost of the chemical of course. But, I have to think that if space is available, increasing the collector area to gather more winter energy and reducing the inventory of chemical and energy would make more sense. In the summer you could sell your saturated chemical to industry and have them replace it with unsaturated to offset your panel cost. Of course now that I have introduced shipping… who wants to live in a shiny reflector farm? Cover industrial buildings and car parks with reflectors, ship or pipe the chemical to houses and have a nicer domestic landscape. I wonder if there are degradation issues? They make a point of being able to store for 18 years which probably only interests survivalists, but make no mention of cycle limits.
- extrapickles 8y ago
  Assuming the at-scale cost is similar to gasoline, it would cost ~$75k just for that much material. If you assume the useful life is 18 years, you would have to spend >$347/mo on heating/cooling for it to be worth it.
  - jvanderbot 8y ago
    You're suggesting buying pre-charged sun juice? That seems less helpful. TFA suggested you can have much less by recharging it, and did not suggest the fluid expires ever (suggested otherwise, actually). It holds energy for 18 years, but can be used in cycle forever.
m_eiman 8y ago
A home in northern Europe needs about 30,000 MJ Really? We live in central Sweden, just outside Gothenburg. According to the estimate from our power company, our house uses about 15,000 MJ per year - and we have a single floor 200 square meter house. It's rated "C" in energy efficiency (which is the minimum rate allowed for new housing now).
- bjelkeman-again 8y ago
  I live in a house from 1909, with a heat pump (bergvärme). We probably use 18000 kWh for hearing in a year, 64800 MJ, at 190 m2 plus basement. 30000 MJ wouldn’t be enough for us I guess.

beefield 8y ago

Do I calculate right that plain water stores energy around 0.2 MJ/kg when heated by 50 degrees celsius? (Specific heat is 4 J/gK) If I am right, ot feels like it would likely be cheaper to just make seasonal heat storages with water.

Someone 8y ago
https://www.ecovat.eu/?lang=en https://www.ecovat.eu/?lang=en aims for water of 90 degrees Celsius (a 70 degree difference with room temperature), and claims heat can be stored with 95% efficiency (possibly exaggerated; the site also says ‘over 90%’) for more than 6 months in a tank 16m deep and 13m in diameter.
- hinkley 8y ago
  And if it leaks into the groundwater you only have to worry about the anti fouling agents you put into the tank, and anything leaching out of the tank lining.

endymi0n 8y ago

Are you sure they're talking about the same thing? Norbornadiene has a formula of C7H8, while the OP team's molecule is composed of "carbon, hydrogen and nitrogen". But thanks for posting some context on current research anyway!

deleted 8y ago

[deleted]

gus_massa 8y ago

IIUC the good part of these molecules is that the energy storage is very stable. With a flywheel the friction will stop it in a few ¿hours/days? The batteries also discharge too fast to store the energy for months. In other comment, someone else proposed to store the energy in hot water, but it's also difficult to keep the hot water for too long.