5 ms·

I am waiting for the day when there is an affordable (<$5k? <$10k as an absolute maximum) residential system that can run on home solar and produce ethanol/hydr

I am waiting for the day when there is an affordable (<$5k? <$10k as an absolute maximum) residential system that can run on home solar and produce ethanol/hydrogen/ammonia/whatever combustible fuel from excess electricity. Round trip efficiency can be horrible, so long as the system is low maintenance and can be configured to run exclusively off of spare generation. Is anything like that on the horizon? Or do all of these liquid fuel synthesis options require industrial pressures/volumes/input electricity so as to forever be out of reach from residential synthesis?

ben_w 4y ago
> combustible fuel from excess electricity. Round trip efficiency can be horrible If that's really all you want, you can get a 9 year old to put together some kitchen waste and art supplies to achieve this. That's how I did it at that age. I did use a battery though, so you might want to check the wiring and add a voltage divider, but those are also easy to build even without understanding. And I have no idea if you even can, let alone should, just pour gaseous hydrogen into, for example, a gas heater's fuel input pipe. But actually making hydrogen is utterly trivial.
- Schroedingersat 4y ago
  Low maintenance, safe, compact, and high enough output is a different story. For the second, you probably want a methanol, methane or ammonia output and they all require high temperatures or exotic materials.
asien 4y ago
In my opinion you are mistaken , affordability does not mean home appliance. Hydro is pretty cheap , does not mean it’s fit for home. Here the best scenario is similar to Singapore - Australia or UK - Morocco remote solar grid. This innovation is very interesting compared to Water- Hydrogene electrolysis that is a bit expensive and needs metals that are going to become difficult to source in the coming decades. Gallium is quiet abundant from my understanding.
35mm 4y ago
This is currently the Lavo hydrogen electrolysis product for home use [1] However the storage tanks are quite small. I would prefer if they made the hydrogen production and storage separate, so you could save up hydrogen in the summer to use in the winter. [1] https://www.lavo.com.au/ https://www.lavo.com.au/
- miahi 4y ago
  Hydrogen storage is not something that you really want to do at home, especially in "saving up" quantities. It is quite happy to explode, you need tremendous pressures and low temperatures for efficient storage, and also hard to contain (many "normal" materials are permeable to hydrogen). [1] [1] https://en.wikipedia.org/wiki/Hydrogen_safety https://en.wikipedia.org/wiki/Hydrogen_safety
  - pkphilip 4y ago
    There are ways of storing hydrogen in metal hydrides at room temperature and pressure. This makes a LOT of sense for people who may want to have an option of buying stored energy - such as those who live in apartments without access to the terraces where solar panels can be deployed. If these metal hydride storage is used similar to how changeable batteries are used, it is conceivable that you could drive up to a place like a fuel station just to change out your metal hydride storage in a matter of a couple of minutes and perhaps even get additional supplementary units packed at the back of the vehicle if they intend to go on a long journey. https://www.frontiersin.org/articles/10.3389/fenrg.2021.616115/full https://www.frontiersin.org/articles/10.3389/fenrg.2021.6161... There has also been recent advances in using Boron Nitride for storage - a perfectly safe chemical. https://www.geelongmanufacturingcouncil.com.au/2022/07/innovative-breakthrough-in-hydrogen-storage-and-transport https://www.geelongmanufacturingcouncil.com.au/2022/07/innov...
    - defrost 4y ago
      There is a case for portable storage, sure. Hydrogen at scale is going to look more like a means to export sunlight energy from equatorial climes (Australia, Sahel, etc) to Europe, the northern US, Canada as required. Efficiencies dictate the most likely roll out is large central generation of electricity and dispersal via the existing electrical grid system. In a similar view individual per apartment solar panels make little sense, panels should be built into entire buildings .. across roofs and across any required parking structures, etc.
xxs 4y ago
10k is an absolutely wishful thinking - 10k is just the low end of a bog standard geothermal pump. Also what's the purpose of the ethanol (the rest are not useful, esp. hydrogen which has to be stored somewhere, ammonia is rather dangerous)? I can imagine making vodka alike - but beyond that, using internal combustion engine to burn it means an extremely very low efficiency to conserve enegy. The energy density is there but the efficiency is not.
- fbdab103 4y ago
  Heh. Yeah, I was thinking that any kind of home synthesis operation was unlikely to offer a financial payback. Hence the low aspirational cost, but you are right that figure is laughably low. Ethanol - easier to synthesize than gasoline (which is a complicated mixture of hydrocarbons). It has ~2/3 energy density of gasoline, which I do not think is horrible. I believe it is also less volatile and easier to store long-term.
- Pigalowda 4y ago
  Couldn't it just burn off excess hydrogen? It would just be H20 byproduct.
jacquesm 4y ago
If you do and you're my neighbor please wait with switching it on until I can move away.
midasuni 4y ago
Why not just a 20kWh battery for energy time shifting. Or are you looking to sell the hydrogen?
- noogle 4y ago
  This will last less than a day. What to do in the winter? If the answer is "use the grid", then we just kick the can to someone else, who will probably use fossil fuels to provide the energy. The basic problem remains - solar/wind are intermittent and fluctuating.
  - midasuni 4y ago
    Compressed air has a higher round trip efficiency than storage, and pumped hydro is twice as efficient as compressed air. However until zero kWh is generated from fossil fuels in summer, solar/wind and battery is a massive gain, even if gas is still used for 2 months a year.
    - noogle 4y ago
      But gas is used also in the summer. And energy is not only electricity - heating is currently done mostly by natural gas, and is often absent from those calculations. Efficiency is irrelevant. The only thing that matter is cost and feasibility. The cost of energy from solar is ~$0.02/kwh and sometimes even $0.00/kwh (when the grid curtails production). Even with 30% efficiency each kwh retrieved from storage will cost a record-low of $0.06/kwh (3-10 times lower than the consumer price). The biggest factor here is the capex and ease-of-use of the equipment. Not the energy input cost.
- ajross 4y ago
  The commenter's goal is presumably season-shifting, which is two orders of magnitude off from feasible battery capacity. In most areas in the US, a full-roof solar system will produce enough energy in aggregate to power the home's use year-round, but there's no way to get all those summertime watt-hours into the lines in winter when the panels are dark. But indeed, no, this just doesn't work. Best available efficiency for round-trip electrolytic fuel production / electricity generation is 40% or so, meaning that those roof panels wouldn't be enough anyway. (Also there's the problem of having every home store a winter's worth of pressurized hydrogen or whatever on-premises. Yikes.) It's not worth it. Home solar is attractive because unlike most infrastructure it scales down really well and is actually feasible to do at the level of an individual user. But, like most infrastructure, seasonal power management is a grid-wide problem and needs to be solved at the utility level. There are plenty of tricks available there that homeowners don't have access to.
michpoch 4y ago
I think the closest to what you need would be some sort of pico hydro with pumped storage.
yummypaint 4y ago
You can effectively accomplish the same thing from an environmental perspective by running your house as efficiently as possible. If you already have home solar, you are reducing the amount of carbon put into the air by power plants. Since CO2 molecules are indistinguishable from each other, that carbon reduction could just as well have come from burning renewable synthetic fuel made at home. If you have a big solar setup and sell excess back to the grid, that carbon reduction will be larger than if you used the same energy to inefficiently synthesize fuel.
- cduzz 4y ago
  You can't operate a car / tractor / hot air balloon with just an efficient house. Also, you can't run your house on an efficient house + solar over the 2-6 months the sun isn't in the right place (in the sky) for very long or when your panels are covered in snow for a week. An efficient house gets you to the table and is a multiplier, but long term energy storage is also really important for lots of people. Hydrogen, though, that stuff's tough. I think 99% of Hydrogen advocates don't understand just how nasty the stuff is.
  - blisterpeanuts 4y ago
    Interestingly, our solar panels seem to shed the snow pretty fast, in fact faster than the plain roof. I guess the black cells warm up in the sunlight and the snow just slides off them after a couple of days. Pre-solar, we used to have to rake the roof to prevent ice dams from building up, but no longer.
  - adrianN 4y ago
    It's probably more efficient to centralize storing weeks worth of energy.
    - chiefalchemist 4y ago
      Perhaps. But then that means the power lines need to be maintained, even when not in use. I'm not sure what the amount is, but it's probably not insignificant.
api 4y ago
A composter costs very little and can product a decent amount of methane. Animals like goats and pigs can produce a lot of dung that will turbocharge that quite a bit. A little searching yields stuff like: https://www.motherearthnews.com/sustainable-living/renewable-energy/biogas-generator-zm0z14aszrob/ https://www.motherearthnews.com/sustainable-living/renewable... The low tech route is far cheaper and easier at small scale if you want to make combustible fuel.
brilee 4y ago
Just use the grid, they can move energy through time a lot more efficiently than you can ever hope to do. https://www.moderndescartes.com/essays/factobattery/ https://www.moderndescartes.com/essays/factobattery/
- natmaka 4y ago
  Even the grid's may benefit from green hydrogen, without any major overhaul: https://www.ge.com/gas-power/future-of-energy/hydrogen-fueled-gas-turbines https://www.ge.com/gas-power/future-of-energy/hydrogen-fuele... Also conceptually related (small-scale): https://news.ycombinator.com/item?id=32694644 https://news.ycombinator.com/item?id=32694644
kseistrup 4y ago
There are also things like MAGFLY that stores electricity (from e.g. solar panels) as kinetic energy in flywheels: - https://www.flywheel.dk/ https://www.flywheel.dk/ - https://wattsuppower.com/flywheel/ https://wattsuppower.com/flywheel/
conradev 4y ago
It’s just a matter of cost. Cost savings will come from improved efficiency and manufacturing innovation. You can make a lot of electrofuels in a distributed way: Hydrogen (Water + Electricity): There are many containerized electrolysers Ammonia (Air + Electricity): https://www.nitricity.co/ https://www.nitricity.co/ Methane (Air + Electricity): https://terraformindustries.com/ https://terraformindustries.com/
- pstuart 4y ago
  Looks promising!
ephbit 4y ago
This [1] comment mentions https://homepowersolutions.de/ https://homepowersolutions.de/ There's also a recent HN topic [2] about it, but without any comments yet. [1] https://news.ycombinator.com/item?id=34298804 https://news.ycombinator.com/item?id=34298804 [2] https://news.ycombinator.com/item?id=34302276 https://news.ycombinator.com/item?id=34302276

ben_w 4y ago

> combustible fuel from excess electricity. Round trip efficiency can be horrible If that's really all you want, you can get a 9 year old to put together some kitchen waste and art supplies to achieve this. That's how I did it at that age. I did use a battery though, so you might want to check the wiring and add a voltage divider, but those are also easy to build even without understanding. And I have no idea if you even can, let alone should, just pour gaseous hydrogen into, for example, a gas heater's fuel input pipe. But actually making hydrogen is utterly trivial.

Schroedingersat 4y ago
Low maintenance, safe, compact, and high enough output is a different story. For the second, you probably want a methanol, methane or ammonia output and they all require high temperatures or exotic materials.

asien 4y ago

In my opinion you are mistaken , affordability does not mean home appliance. Hydro is pretty cheap , does not mean it’s fit for home. Here the best scenario is similar to Singapore - Australia or UK - Morocco remote solar grid. This innovation is very interesting compared to Water- Hydrogene electrolysis that is a bit expensive and needs metals that are going to become difficult to source in the coming decades. Gallium is quiet abundant from my understanding.

35mm 4y ago

This is currently the Lavo hydrogen electrolysis product for home use [1] However the storage tanks are quite small. I would prefer if they made the hydrogen production and storage separate, so you could save up hydrogen in the summer to use in the winter. [1] https://www.lavo.com.au/ https://www.lavo.com.au/

miahi 4y ago
Hydrogen storage is not something that you really want to do at home, especially in "saving up" quantities. It is quite happy to explode, you need tremendous pressures and low temperatures for efficient storage, and also hard to contain (many "normal" materials are permeable to hydrogen). [1] [1] https://en.wikipedia.org/wiki/Hydrogen_safety https://en.wikipedia.org/wiki/Hydrogen_safety
- pkphilip 4y ago
  There are ways of storing hydrogen in metal hydrides at room temperature and pressure. This makes a LOT of sense for people who may want to have an option of buying stored energy - such as those who live in apartments without access to the terraces where solar panels can be deployed. If these metal hydride storage is used similar to how changeable batteries are used, it is conceivable that you could drive up to a place like a fuel station just to change out your metal hydride storage in a matter of a couple of minutes and perhaps even get additional supplementary units packed at the back of the vehicle if they intend to go on a long journey. https://www.frontiersin.org/articles/10.3389/fenrg.2021.616115/full https://www.frontiersin.org/articles/10.3389/fenrg.2021.6161... There has also been recent advances in using Boron Nitride for storage - a perfectly safe chemical. https://www.geelongmanufacturingcouncil.com.au/2022/07/innovative-breakthrough-in-hydrogen-storage-and-transport https://www.geelongmanufacturingcouncil.com.au/2022/07/innov...
  - defrost 4y ago
    There is a case for portable storage, sure. Hydrogen at scale is going to look more like a means to export sunlight energy from equatorial climes (Australia, Sahel, etc) to Europe, the northern US, Canada as required. Efficiencies dictate the most likely roll out is large central generation of electricity and dispersal via the existing electrical grid system. In a similar view individual per apartment solar panels make little sense, panels should be built into entire buildings .. across roofs and across any required parking structures, etc.

xxs 4y ago

10k is an absolutely wishful thinking - 10k is just the low end of a bog standard geothermal pump. Also what's the purpose of the ethanol (the rest are not useful, esp. hydrogen which has to be stored somewhere, ammonia is rather dangerous)? I can imagine making vodka alike - but beyond that, using internal combustion engine to burn it means an extremely very low efficiency to conserve enegy. The energy density is there but the efficiency is not.

fbdab103 4y ago
Heh. Yeah, I was thinking that any kind of home synthesis operation was unlikely to offer a financial payback. Hence the low aspirational cost, but you are right that figure is laughably low. Ethanol - easier to synthesize than gasoline (which is a complicated mixture of hydrocarbons). It has ~2/3 energy density of gasoline, which I do not think is horrible. I believe it is also less volatile and easier to store long-term.
Pigalowda 4y ago
Couldn't it just burn off excess hydrogen? It would just be H20 byproduct.

jacquesm 4y ago

If you do and you're my neighbor please wait with switching it on until I can move away.

midasuni 4y ago

Why not just a 20kWh battery for energy time shifting. Or are you looking to sell the hydrogen?

noogle 4y ago
This will last less than a day. What to do in the winter? If the answer is "use the grid", then we just kick the can to someone else, who will probably use fossil fuels to provide the energy. The basic problem remains - solar/wind are intermittent and fluctuating.
- midasuni 4y ago
  Compressed air has a higher round trip efficiency than storage, and pumped hydro is twice as efficient as compressed air. However until zero kWh is generated from fossil fuels in summer, solar/wind and battery is a massive gain, even if gas is still used for 2 months a year.
  - noogle 4y ago
    But gas is used also in the summer. And energy is not only electricity - heating is currently done mostly by natural gas, and is often absent from those calculations. Efficiency is irrelevant. The only thing that matter is cost and feasibility. The cost of energy from solar is ~$0.02/kwh and sometimes even $0.00/kwh (when the grid curtails production). Even with 30% efficiency each kwh retrieved from storage will cost a record-low of $0.06/kwh (3-10 times lower than the consumer price). The biggest factor here is the capex and ease-of-use of the equipment. Not the energy input cost.
ajross 4y ago
The commenter's goal is presumably season-shifting, which is two orders of magnitude off from feasible battery capacity. In most areas in the US, a full-roof solar system will produce enough energy in aggregate to power the home's use year-round, but there's no way to get all those summertime watt-hours into the lines in winter when the panels are dark. But indeed, no, this just doesn't work. Best available efficiency for round-trip electrolytic fuel production / electricity generation is 40% or so, meaning that those roof panels wouldn't be enough anyway. (Also there's the problem of having every home store a winter's worth of pressurized hydrogen or whatever on-premises. Yikes.) It's not worth it. Home solar is attractive because unlike most infrastructure it scales down really well and is actually feasible to do at the level of an individual user. But, like most infrastructure, seasonal power management is a grid-wide problem and needs to be solved at the utility level. There are plenty of tricks available there that homeowners don't have access to.

michpoch 4y ago

I think the closest to what you need would be some sort of pico hydro with pumped storage.

yummypaint 4y ago

You can effectively accomplish the same thing from an environmental perspective by running your house as efficiently as possible. If you already have home solar, you are reducing the amount of carbon put into the air by power plants. Since CO2 molecules are indistinguishable from each other, that carbon reduction could just as well have come from burning renewable synthetic fuel made at home. If you have a big solar setup and sell excess back to the grid, that carbon reduction will be larger than if you used the same energy to inefficiently synthesize fuel.

cduzz 4y ago
You can't operate a car / tractor / hot air balloon with just an efficient house. Also, you can't run your house on an efficient house + solar over the 2-6 months the sun isn't in the right place (in the sky) for very long or when your panels are covered in snow for a week. An efficient house gets you to the table and is a multiplier, but long term energy storage is also really important for lots of people. Hydrogen, though, that stuff's tough. I think 99% of Hydrogen advocates don't understand just how nasty the stuff is.
- blisterpeanuts 4y ago
  Interestingly, our solar panels seem to shed the snow pretty fast, in fact faster than the plain roof. I guess the black cells warm up in the sunlight and the snow just slides off them after a couple of days. Pre-solar, we used to have to rake the roof to prevent ice dams from building up, but no longer.
- adrianN 4y ago
  It's probably more efficient to centralize storing weeks worth of energy.
  - chiefalchemist 4y ago
    Perhaps. But then that means the power lines need to be maintained, even when not in use. I'm not sure what the amount is, but it's probably not insignificant.

api 4y ago

A composter costs very little and can product a decent amount of methane. Animals like goats and pigs can produce a lot of dung that will turbocharge that quite a bit. A little searching yields stuff like: https://www.motherearthnews.com/sustainable-living/renewable-energy/biogas-generator-zm0z14aszrob/ https://www.motherearthnews.com/sustainable-living/renewable... The low tech route is far cheaper and easier at small scale if you want to make combustible fuel.

brilee 4y ago

Just use the grid, they can move energy through time a lot more efficiently than you can ever hope to do. https://www.moderndescartes.com/essays/factobattery/ https://www.moderndescartes.com/essays/factobattery/

natmaka 4y ago
Even the grid's may benefit from green hydrogen, without any major overhaul: https://www.ge.com/gas-power/future-of-energy/hydrogen-fueled-gas-turbines https://www.ge.com/gas-power/future-of-energy/hydrogen-fuele... Also conceptually related (small-scale): https://news.ycombinator.com/item?id=32694644 https://news.ycombinator.com/item?id=32694644

kseistrup 4y ago

There are also things like MAGFLY that stores electricity (from e.g. solar panels) as kinetic energy in flywheels: - https://www.flywheel.dk/ https://www.flywheel.dk/ - https://wattsuppower.com/flywheel/ https://wattsuppower.com/flywheel/

conradev 4y ago

It’s just a matter of cost. Cost savings will come from improved efficiency and manufacturing innovation. You can make a lot of electrofuels in a distributed way: Hydrogen (Water + Electricity): There are many containerized electrolysers Ammonia (Air + Electricity): https://www.nitricity.co/ https://www.nitricity.co/ Methane (Air + Electricity): https://terraformindustries.com/ https://terraformindustries.com/

pstuart 4y ago
Looks promising!

ephbit 4y ago

This [1] comment mentions https://homepowersolutions.de/ https://homepowersolutions.de/ There's also a recent HN topic [2] about it, but without any comments yet. [1] https://news.ycombinator.com/item?id=34298804 https://news.ycombinator.com/item?id=34298804 [2] https://news.ycombinator.com/item?id=34302276 https://news.ycombinator.com/item?id=34302276