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#11
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Rechargeable Zinc-Air battery moves closer to commercialization
On Sat, 29 Sep 2018 16:38:53 -0700, Bill.Daniels wrote:
But, an electric motor is more than three times as efficient as an internal combustion engine - 98% vs. 33% - so they don't need as much 'fuel'. Well, getting on that way - but certainly no better if you include the generation and charging efficiencies. Actually, all I was looking to do was to put numbers to the overall efficiency of electric storage in terms of weight or volume compared with hydrocarbon fuels. Batteries are much worse here than petrol. And there's another demerit too: run the tank dry on a turbo or jet and the empty tank is nice and light for the rest of the flight home, while a battery that has been run flat is no lighter than when it was fully charged. A quick scan for zinc-air battery characteristics suggests they are only suitable for low power applications, tend to have a high self-discharge rate and don't like high temperatures or humidity. Nobody, that I found anyway, is quoting energy density (kWh/kg) or volumetric efficiency (kWh/ litre). Bottom line: I like the idea of electric powered vehicles. But in this application the volume and weight of energy storage systems is all- important, but electrochemistry is against any large improvement, at least for rechargeable batteries using currently proven chemistry. So far nobody has gotten better results from fuel-cells either, or we'd be seeing them in cars. -- Martin | martin at Gregorie | gregorie dot org |
#12
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Rechargeable Zinc-Air battery moves closer to commercialization
On Saturday, September 29, 2018 at 6:30:20 PM UTC-7, Martin Gregorie wrote:
On Sat, 29 Sep 2018 16:38:53 -0700, Bill.Daniels wrote: But, an electric motor is more than three times as efficient as an internal combustion engine - 98% vs. 33% - so they don't need as much 'fuel'. Well, getting on that way - but certainly no better if you include the generation and charging efficiencies. Actually, all I was looking to do was to put numbers to the overall efficiency of electric storage in terms of weight or volume compared with hydrocarbon fuels. Batteries are much worse here than petrol. And there's another demerit too: run the tank dry on a turbo or jet and the empty tank is nice and light for the rest of the flight home, while a battery that has been run flat is no lighter than when it was fully charged. A quick scan for zinc-air battery characteristics suggests they are only suitable for low power applications, tend to have a high self-discharge rate and don't like high temperatures or humidity. Nobody, that I found anyway, is quoting energy density (kWh/kg) or volumetric efficiency (kWh/ litre). Bottom line: I like the idea of electric powered vehicles. But in this application the volume and weight of energy storage systems is all- important, but electrochemistry is against any large improvement, at least for rechargeable batteries using currently proven chemistry. So far nobody has gotten better results from fuel-cells either, or we'd be seeing them in cars. -- Martin | martin at Gregorie | gregorie dot org Here is an interesting 2015 presentation on zinc-air batteries that indicates the possibility for very high energy densities (1200+ WHr/kg): https://www.csm.ornl.gov/BLI8/presen...UNIST-BYI8.pdf Tom |
#13
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Rechargeable Zinc-Air battery moves closer to commercialization
On Friday, September 28, 2018 at 5:58:43 PM UTC+2, Martin Gregorie wrote:
On Fri, 28 Sep 2018 07:48:13 -0700, Soartech wrote: Ultra capacitors ! A gallon of gasoline contains 120 million Joules of energy. A more useful equivalent for comparison is that a litre of petrol is as near as dammit 10 kWh in energy terms - and petrol spiked with methanol will be a bit less: 9-9.5 kWh at a guess, So a US gallon (3.78l) would be the equivalent of 37.8 kWh of unadulterated petrol or 34-36 kWh if its a gasoline/methanol blend. By comparison, the Gen 2 FES battery has 14 cells, each of 2.1 kWh, or 29.4 kWh for the standard 14 cell pack, so an hPh Shark (dual packs carried has just less than 60kWh of energy onboard, or 1.6 US gallons of avgas equivalent. The dual packs are about 18 litres total volume, so on a volumetric basis they're about 1/3 as good as petrol when it comes to storing energy in limited space. -- Martin | martin at Gregorie | gregorie dot org He did the Math.. |
#14
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Rechargeable Zinc-Air battery moves closer to commercialization
On Sat, 29 Sep 2018 23:07:27 -0700, 2G wrote:
On Saturday, September 29, 2018 at 6:30:20 PM UTC-7, Martin Gregorie wrote: On Sat, 29 Sep 2018 16:38:53 -0700, Bill.Daniels wrote: But, an electric motor is more than three times as efficient as an internal combustion engine - 98% vs. 33% - so they don't need as much 'fuel'. Well, getting on that way - but certainly no better if you include the generation and charging efficiencies. Actually, all I was looking to do was to put numbers to the overall efficiency of electric storage in terms of weight or volume compared with hydrocarbon fuels. Batteries are much worse here than petrol. And there's another demerit too: run the tank dry on a turbo or jet and the empty tank is nice and light for the rest of the flight home, while a battery that has been run flat is no lighter than when it was fully charged. A quick scan for zinc-air battery characteristics suggests they are only suitable for low power applications, tend to have a high self-discharge rate and don't like high temperatures or humidity. Nobody, that I found anyway, is quoting energy density (kWh/kg) or volumetric efficiency (kWh/ litre). Bottom line: I like the idea of electric powered vehicles. But in this application the volume and weight of energy storage systems is all- important, but electrochemistry is against any large improvement, at least for rechargeable batteries using currently proven chemistry. So far nobody has gotten better results from fuel-cells either, or we'd be seeing them in cars. -- Martin | martin at Gregorie | gregorie dot org Here is an interesting 2015 presentation on zinc-air batteries that indicates the possibility for very high energy densities (1200+ WHr/kg): https://www.csm.ornl.gov/BLI8/presen...UNIST-BYI8.pdf Interesting stuff but, unless I totally misunderstood the presentation: - the theoretical energy density of ZAB is around 170% of what LiFePO4 can do (0.3 kWh/kg vs 0.18 kWh/kg). no comparison with Li-ion made. (page 4). - page 18 quotes a measured 1 kWh/kg. - page 32 quotes 0.0357 kWh/kg (0.41 kWh/litre) for an experimental ZAB rig. - page 36 quotes 1.9 kWh/kg (0.0036 kWh/litre) for a flexible cable format battery. .... all quite a way short of the 10 kWh/litre (12.5 kWh/kg) of hydrocarbon energy storage. The sort of high power performance needed for a car or aircraft motor wasn't really discussed or apparent in the accompanying numbers, charts and graphs. Still, looks to be worth watching and the possibility of almost instant recharge by replacing the zinc becomes interesting if a cell with high power output can be designed for easy 'slip out/slip in' zinc replacement without needing special equipment, e.g to deal with the (highly alkaline) potassium hydroxide electrolyte. The possibility of recycling the 'used' zinc externally sounds good too. -- Martin | martin at Gregorie | gregorie dot org |
#15
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Rechargeable Zinc-Air battery moves closer to commercialization
On Sunday, September 30, 2018 at 4:23:22 AM UTC-7, Martin Gregorie wrote:
On Sat, 29 Sep 2018 23:07:27 -0700, 2G wrote: On Saturday, September 29, 2018 at 6:30:20 PM UTC-7, Martin Gregorie wrote: On Sat, 29 Sep 2018 16:38:53 -0700, Bill.Daniels wrote: But, an electric motor is more than three times as efficient as an internal combustion engine - 98% vs. 33% - so they don't need as much 'fuel'. Well, getting on that way - but certainly no better if you include the generation and charging efficiencies. Actually, all I was looking to do was to put numbers to the overall efficiency of electric storage in terms of weight or volume compared with hydrocarbon fuels. Batteries are much worse here than petrol. And there's another demerit too: run the tank dry on a turbo or jet and the empty tank is nice and light for the rest of the flight home, while a battery that has been run flat is no lighter than when it was fully charged. A quick scan for zinc-air battery characteristics suggests they are only suitable for low power applications, tend to have a high self-discharge rate and don't like high temperatures or humidity. Nobody, that I found anyway, is quoting energy density (kWh/kg) or volumetric efficiency (kWh/ litre). Bottom line: I like the idea of electric powered vehicles. But in this application the volume and weight of energy storage systems is all- important, but electrochemistry is against any large improvement, at least for rechargeable batteries using currently proven chemistry. So far nobody has gotten better results from fuel-cells either, or we'd be seeing them in cars. -- Martin | martin at Gregorie | gregorie dot org Here is an interesting 2015 presentation on zinc-air batteries that indicates the possibility for very high energy densities (1200+ WHr/kg): https://www.csm.ornl.gov/BLI8/presen...UNIST-BYI8.pdf Interesting stuff but, unless I totally misunderstood the presentation: - the theoretical energy density of ZAB is around 170% of what LiFePO4 can do (0.3 kWh/kg vs 0.18 kWh/kg). no comparison with Li-ion made. (page 4). - page 18 quotes a measured 1 kWh/kg. - page 32 quotes 0.0357 kWh/kg (0.41 kWh/litre) for an experimental ZAB rig. - page 36 quotes 1.9 kWh/kg (0.0036 kWh/litre) for a flexible cable format battery. ... all quite a way short of the 10 kWh/litre (12.5 kWh/kg) of hydrocarbon energy storage. The sort of high power performance needed for a car or aircraft motor wasn't really discussed or apparent in the accompanying numbers, charts and graphs. Still, looks to be worth watching and the possibility of almost instant recharge by replacing the zinc becomes interesting if a cell with high power output can be designed for easy 'slip out/slip in' zinc replacement without needing special equipment, e.g to deal with the (highly alkaline) potassium hydroxide electrolyte. The possibility of recycling the 'used' zinc externally sounds good too. -- Martin | martin at Gregorie | gregorie dot org Here is an excellent paper that discusses the current state-of-the-art in zinc-air batteries: https://www.researchgate.net/profile...rspectives.pdf I haven't had time yet to read the full paper, but what I have read so far is most instructive. Tom |
#16
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Rechargeable Zinc-Air battery moves closer to commercialization
On Sun, 30 Sep 2018 22:37:42 -0700, 2G wrote:
On Sunday, September 30, 2018 at 4:23:22 AM UTC-7, Martin Gregorie wrote: On Sat, 29 Sep 2018 23:07:27 -0700, 2G wrote: On Saturday, September 29, 2018 at 6:30:20 PM UTC-7, Martin Gregorie wrote: On Sat, 29 Sep 2018 16:38:53 -0700, Bill.Daniels wrote: But, an electric motor is more than three times as efficient as an internal combustion engine - 98% vs. 33% - so they don't need as much 'fuel'. Well, getting on that way - but certainly no better if you include the generation and charging efficiencies. Actually, all I was looking to do was to put numbers to the overall efficiency of electric storage in terms of weight or volume compared with hydrocarbon fuels. Batteries are much worse here than petrol. And there's another demerit too: run the tank dry on a turbo or jet and the empty tank is nice and light for the rest of the flight home, while a battery that has been run flat is no lighter than when it was fully charged. A quick scan for zinc-air battery characteristics suggests they are only suitable for low power applications, tend to have a high self-discharge rate and don't like high temperatures or humidity. Nobody, that I found anyway, is quoting energy density (kWh/kg) or volumetric efficiency (kWh/ litre). Bottom line: I like the idea of electric powered vehicles. But in this application the volume and weight of energy storage systems is all- important, but electrochemistry is against any large improvement, at least for rechargeable batteries using currently proven chemistry. So far nobody has gotten better results from fuel-cells either, or we'd be seeing them in cars. -- Martin | martin at Gregorie | gregorie dot org Here is an interesting 2015 presentation on zinc-air batteries that indicates the possibility for very high energy densities (1200+ WHr/kg): https://www.csm.ornl.gov/BLI8/presen...UNIST-BYI8.pdf Interesting stuff but, unless I totally misunderstood the presentation: - the theoretical energy density of ZAB is around 170% of what LiFePO4 can do (0.3 kWh/kg vs 0.18 kWh/kg). no comparison with Li-ion made. (page 4). - page 18 quotes a measured 1 kWh/kg. - page 32 quotes 0.0357 kWh/kg (0.41 kWh/litre) for an experimental ZAB rig. - page 36 quotes 1.9 kWh/kg (0.0036 kWh/litre) for a flexible cable format battery. ... all quite a way short of the 10 kWh/litre (12.5 kWh/kg) of hydrocarbon energy storage. The sort of high power performance needed for a car or aircraft motor wasn't really discussed or apparent in the accompanying numbers, charts and graphs. Still, looks to be worth watching and the possibility of almost instant recharge by replacing the zinc becomes interesting if a cell with high power output can be designed for easy 'slip out/slip in' zinc replacement without needing special equipment, e.g to deal with the (highly alkaline) potassium hydroxide electrolyte. The possibility of recycling the 'used' zinc externally sounds good too. -- Martin | martin at Gregorie | gregorie dot org Here is an excellent paper that discusses the current state-of-the-art in zinc-air batteries: https://www.researchgate.net/profile...6/publication/ 311098275_Electrically_Rechargeable_Zinc- Air_Batteries_Progress_Challenges_and_Perspectives/links/ 59da6e38458515a5bc2b43b1/Electrically-Rechargeable-Zinc-Air-Batteries- Progress-Challenges-and-Perspectives.pdf I haven't had time yet to read the full paper, but what I have read so far is most instructive. Tom Thanks for that. Saved for reading later. -- Martin | martin at Gregorie | gregorie dot org |
#17
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Rechargeable Zinc-Air battery moves closer to commercialization
perjantai 28. syyskuuta 2018 18.58.43 UTC+3 Martin Gregorie kirjoitti:
By comparison, the Gen 2 FES battery has 14 cells, each of 2.1 kWh, or 29.4 kWh for the standard 14 cell pack, so an hPh Shark (dual packs carried has just less than 60kWh of energy onboard, or 1.6 US gallons of avgas equivalent. I think FES battery has 14 cells at 41 Ah per cell. With 58 Volts you get the 2,1 kWh number (per battery back, and with some internal power loss). Two batteries and you end up 4,2 kWh of energy which gives you advertized hour flight duration with minimal power (4-5kW). |
#18
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Rechargeable Zinc-Air battery moves closer to commercialization
One of the funny things with true metal air batteries is that they gain weight as they discharge (Zn = ZnO2), and surprisingly (cough) no promoter of the tech quotes Wh/kg for discharged batteries, which is what you'll be carrying around... they partially look so attractive because of that little cheat!
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#19
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Rechargeable Zinc-Air battery moves closer to commercialization
Wow!Â* Looking at the atomic mass of each, that would be about a 50%
increase (~65 for Zn and 16 or O) if all of the zinc was oxidized! Now I'm no chemist, that that looks HUGE to me! On 11/15/2018 10:19 PM, wrote: One of the funny things with true metal air batteries is that they gain weight as they discharge (Zn = ZnO2), and surprisingly (cough) no promoter of the tech quotes Wh/kg for discharged batteries, which is what you'll be carrying around... they partially look so attractive because of that little cheat! -- Dan, 5J |
#20
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Rechargeable Zinc-Air battery moves closer to commercialization
On Fri, 16 Nov 2018 07:36:18 -0700, Dan Marotta wrote:
Wow!Â* Looking at the atomic mass of each, that would be about a 50% increase (~65 for Zn and 16 or O) if all of the zinc was oxidized! Now I'm no chemist, that that looks HUGE to me! Yep - thats approximately a 25% weight increase. The zinc electrode will expand too: Zinc has a density of 7.14 vs 5.6 for ZnO, which implies something like a 28% volume increase if all the zinc in the battery of is oxidised when fully discharged. However, 100% oxidation is rather unlikely in any practical battery, and dealing with the volume increase means designing the case so it doesn't split when the battery is fully discharged. -- Martin | martin at Gregorie | gregorie dot org |
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