6 ms·

Thanks! Yes, and our research agrees that the short-life of Li-ion is a problem, and it's one of the reasons why we believe our solution has so much more promis

Thanks! Yes, and our research agrees that the short-life of Li-ion is a problem, and it's one of the reasons why we believe our solution has so much more promise than Li-ion for grid scale storage. The pump/turbine technology we use is the same that's been used for a hundred plus years for traditional pumped hydro dams, and the maintenance cost is very low. The life of a project is 40+ years. And in reality it can be 100 years with relatively low amount of maintenance. The San Diego County research posted on our website has good figures on this. thanks!

JoeAltmaier 7y ago
Hydro has more loss, which is worrisome. Maybe 5X the loss per cycle than battery?
- jlevers 7y ago
  Interesting, I didn't know that. Are there practical ways to decrease the amount of loss? Do you know what the actual loss percentages are for each?
- syllable_studio 7y ago
  Hmm, I think what you're alluding to is that pumped hydro is about 70-85% efficient and Li-ion is sometimes quoted at 100% efficient (in theory). But here are some more details. In reality, when Li-ion batteries are installed in a large system, I believe the round-trip efficiency is quoted much closer to PHS. Sorry, i can't find the best research to cite right now, but here are a couple sources i found with a quick search. "lithium-based ESS rated for two hours at rated power will have an AC round-trip efficiency of 75 to 85%." https://www.windpowerengineering.com/how-three-battery-types-work-in-grid-scale-energy-storage-systems/ https://www.windpowerengineering.com/how-three-battery-types... https://www.sciencedirect.com/science/article/abs/pii/S0306261917315696 https://www.sciencedirect.com/science/article/abs/pii/S03062... "Conversion round-trip efficiency is in the range of 70–80%" This one says 90-95% https://researchinterfaces.com/lithium-ion-batteries-grid-energy-storage/ https://researchinterfaces.com/lithium-ion-batteries-grid-en... I've heard that Li-ion installations can get up to 90-95% round trip, which is fantastic, and better than PHS for sure. But it's not the most important detail in the equation. Here's why: One thing to remember is that power is lost all over the system in conversion and transmission. So raw efficiency can be less important than getting the right capacity to the right place on the grid. And that brings us to cost. Even though PHS is a little less efficient than Li-ion, 85% for PHS is still really good. (see other my other comment below about 70% vs 85%) And the math shows that investing in PHS is simply cheaper -- even after assuming that Li-ion will drop in price by 3x in the coming decades. This is partly because Li-ion has a much shorter life span and needs to be replaced about every decade. Li-ion is still great and super important! But it's not looking like the best contender right now for grid-scale storage.

JoeAltmaier 7y ago

Hydro has more loss, which is worrisome. Maybe 5X the loss per cycle than battery?

jlevers 7y ago
Interesting, I didn't know that. Are there practical ways to decrease the amount of loss? Do you know what the actual loss percentages are for each?
syllable_studio 7y ago
Hmm, I think what you're alluding to is that pumped hydro is about 70-85% efficient and Li-ion is sometimes quoted at 100% efficient (in theory). But here are some more details. In reality, when Li-ion batteries are installed in a large system, I believe the round-trip efficiency is quoted much closer to PHS. Sorry, i can't find the best research to cite right now, but here are a couple sources i found with a quick search. "lithium-based ESS rated for two hours at rated power will have an AC round-trip efficiency of 75 to 85%." https://www.windpowerengineering.com/how-three-battery-types-work-in-grid-scale-energy-storage-systems/ https://www.windpowerengineering.com/how-three-battery-types... https://www.sciencedirect.com/science/article/abs/pii/S0306261917315696 https://www.sciencedirect.com/science/article/abs/pii/S03062... "Conversion round-trip efficiency is in the range of 70–80%" This one says 90-95% https://researchinterfaces.com/lithium-ion-batteries-grid-energy-storage/ https://researchinterfaces.com/lithium-ion-batteries-grid-en... I've heard that Li-ion installations can get up to 90-95% round trip, which is fantastic, and better than PHS for sure. But it's not the most important detail in the equation. Here's why: One thing to remember is that power is lost all over the system in conversion and transmission. So raw efficiency can be less important than getting the right capacity to the right place on the grid. And that brings us to cost. Even though PHS is a little less efficient than Li-ion, 85% for PHS is still really good. (see other my other comment below about 70% vs 85%) And the math shows that investing in PHS is simply cheaper -- even after assuming that Li-ion will drop in price by 3x in the coming decades. This is partly because Li-ion has a much shorter life span and needs to be replaced about every decade. Li-ion is still great and super important! But it's not looking like the best contender right now for grid-scale storage.