3 ms·

So what is the idea? You place a bunch of solar panels in a sunny place that also has water. Then you directly power the grid when it is sunny and all power i

So what is the idea? You place a bunch of solar panels in a sunny place that also has water. Then you directly power the grid when it is sunny and all power is needed. When not needed, you power the catalyst, storing the hydrogen. When it is dark, you use the hydrogen to create power and (maybe) heat.

ProCynic 14y ago
Pretty much. One of the biggest problems with a lot of renewable energy is it's not reliable. Sun doesn't shine, wind isn't blowing, etc. So you need a way to store energy in a buffer to smooth out fluctuations. Hydrogen is looking like the best long term bet for that. You might even be able to use it for hydrogen cars, but then you run into problems with transportation and crash-proof storage that you don't have with just a tank in your back yard.
uvdiv 14y ago
Besides the current costs (especially the solar PV part), there's the problem that you're throwing away most of your energy in the [electricity => hydrogen => electricity] loop. Electrolysis isn't perfect [1], but the big waste is electricity generation, with the best hydrogen fuel cells being only 50-60% efficient [2, SOFC "predicted"] (turbines smaller than utility scale would be far worse). In the most optimistic case you lose half of your stored energy (more likely 2/3rd). Realistically you'd have to store almost all of your electricity -- compare solar output, a very short midday peak, with electricity demand, which in many places is nearly constant over time. Almost of all of it would go through the 50%+ storage losses, which means the solar part (PV + inverter + etc.) of your costs are more than doubled, amortized per kWh. So economically, practically anything is better than local hydrogen storage. (Under the premise that solar PV is not effectively free, which is an understatement to put it mildly). [1] http://en.wikipedia.org/wiki/Electrolysis#Electrolysis_of_water http://en.wikipedia.org/wiki/Electrolysis#Electrolysis_of_wa... [2] http://www1.eere.energy.gov/hydrogenandfuelcells/fuelcells/fc_types.html http://www1.eere.energy.gov/hydrogenandfuelcells/fuelcells/f...

ProCynic 14y ago

Pretty much. One of the biggest problems with a lot of renewable energy is it's not reliable. Sun doesn't shine, wind isn't blowing, etc. So you need a way to store energy in a buffer to smooth out fluctuations. Hydrogen is looking like the best long term bet for that. You might even be able to use it for hydrogen cars, but then you run into problems with transportation and crash-proof storage that you don't have with just a tank in your back yard.

uvdiv 14y ago

Besides the current costs (especially the solar PV part), there's the problem that you're throwing away most of your energy in the [electricity => hydrogen => electricity] loop. Electrolysis isn't perfect [1], but the big waste is electricity generation, with the best hydrogen fuel cells being only 50-60% efficient [2, SOFC "predicted"] (turbines smaller than utility scale would be far worse). In the most optimistic case you lose half of your stored energy (more likely 2/3rd). Realistically you'd have to store almost all of your electricity -- compare solar output, a very short midday peak, with electricity demand, which in many places is nearly constant over time. Almost of all of it would go through the 50%+ storage losses, which means the solar part (PV + inverter + etc.) of your costs are more than doubled, amortized per kWh. So economically, practically anything is better than local hydrogen storage. (Under the premise that solar PV is not effectively free, which is an understatement to put it mildly). [1] http://en.wikipedia.org/wiki/Electrolysis#Electrolysis_of_water http://en.wikipedia.org/wiki/Electrolysis#Electrolysis_of_wa... [2] http://www1.eere.energy.gov/hydrogenandfuelcells/fuelcells/fc_types.html http://www1.eere.energy.gov/hydrogenandfuelcells/fuelcells/f...