6 ms·

As stated, that is "at most". A usual UPS is 80-89% efficient. Even still, assuming they were 90% efficient, is it worth the extra 10% energy consumption just

As stated, that is "at most". A usual UPS is 80-89% efficient. Even still, assuming they were 90% efficient, is it worth the extra 10% energy consumption just so you can run your computer for 1 hour at night when the solar energy provider ups their rate? You still need to consume the additional energy in the day to charge the battery. For me to label it efficient, I'd be looking for 95%+, but 99% would be preferable. Remember, this efficiency declines as the battery ages. You only get a few years of efficient use before it declines significantly. Then you have a disposal problem. A typical UPS uses lead-acid batteries, the same type used in cars. They're not environmentally friendly.

pfdietz 6y ago
Of course it's worth it. Losing 10% of the energy in storage is close to trivial, particularly if that energy is otherwise curtailed excess production. It would be worthwhile to use far less efficient storage for long term load leveling, if the capital cost were low enough. Hydrogen with cheap electrolysers and combined cycle turbines might have a round trip efficiency of 33% -- and that would be GREAT as a last component for getting to a fossil-fuel free grid, particularly at high latitude.
- sparkie 6y ago
  But this is missing the elephant in the living room (this thread), which is nuclear. One of the main issues with nuclear is that it isn't cost effective to turn on/off to meet demand changes in day and night. Nuclear power stations usually only generate energy for the baseload. If we were to cut energy consumption down at night (by increasing costs), the baseload would also drop, and leave an even larger gap to meet for peak, which must be met by other means like solar or fossil fuels. If anything, we want to shift some energy consumption to off-peak times like early hours, so that the baseload is higher and can be met by cheaper nuclear, along with other solutions like tidal. If this happens, the gap between peak and baseload during the day/evening will be smaller, and can be met with solutions like (concentrating) solar which are more environmentally friendly than photovoltaics + batteries.
  - pfdietz 6y ago
    No, it's not missing nuclear. Hydrogen is the stake through the heart that kills the last argument for nuclear (that batteries can't handle long term load leveling). With reasonable projections of where the costs of renewables and storage are going, nuclear gets optimized right out of the picture.
    - sparkie 6y ago
      Yeah, I can't take you seriously. GL with your blackouts and energy quotas, oh, and reliance of fossil fuels. Where do you think the energy is going to come from to perform electrolysis for hydrogen? solar? You are nowhere near meeting basic needs yet with solar, wind, tidal, geothermal combined. (3 out of the 4 can be intermittent/dependant on environmental conditions and are not reliable). Remember, energy demand is going to continue increasing. By the time your renewable utopia exists, you're going to need to double or triple its capacity. Perhaps I'm unaware of some technological breakthrough which can produce hydrogen using little energy? Nuclear is great once up-front costs are paid. Most future energy demand will be met by nuclear. Cleaner renewables will be there to provide additional capacity above baseload, but I wouldn't depend on them to meet basic needs. I have pondered whether it would be possible to generate hydrogen more cheaply via concentrating solar or geothermal. The hotter you can get water before performing electrolysis, the less electricity will be required. Above 3k Celsius, the atoms in water will dissociate without electricity. You might have a reasonable argument against nuclear if you don't need to spend 3x the electricity creating the hydrogen than you'll get back from it.
      - pfdietz 6y ago
        > You are nowhere near meeting basic needs yet with solar, wind, tidal, geothermal combined. Ah, the old "it hasn't happened yet, therefore it can't happen" argument. I'm sure if you honestly think about it you can realize why that argument is nonsense. > (3 out of the 4 can be intermittent/dependant on environmental conditions and are not reliable). We're talking here about power for hydrogen production. Intermittency doesn't matter much for that (it requires the electrolysers be cheap, but their costs have plummeted recently, so that's no longer an obstacle.) > Perhaps I'm unaware of some technological breakthrough which can produce hydrogen using little energy? Perhaps you could stop using strawman arguments? Hydrogen doesn't have to be produced with little energy in order for hydrogen storage to be viable. The energy that is used just needs to be sufficiently cheap. You know, like that $0.013/kWh power from large scale PV in the UAE? And that's only the latest in a constant string of record low bids. > Nuclear is great once up-front costs are paid. Yes, if you can get the Nuclear Fairy to wave a magic wand and make the power plant appear for free, it's much less expensive (but even then, the operating costs will be much higher than renewables). In the real world where real money has to be paid to build nuclear power plants, not so much. > I have pondered whether it would be possible to generate hydrogen more cheaply via concentrating solar or geothermal. Neither of these are competitive with PV now. Hell, it's now cheaper to make domestic solar hot water with PV and a resistive heater than it would be to use solar thermal collectors (although a heat pump water heater would be cheaper still). PV has gotten THAT cheap.

pfdietz 6y ago

Of course it's worth it. Losing 10% of the energy in storage is close to trivial, particularly if that energy is otherwise curtailed excess production. It would be worthwhile to use far less efficient storage for long term load leveling, if the capital cost were low enough. Hydrogen with cheap electrolysers and combined cycle turbines might have a round trip efficiency of 33% -- and that would be GREAT as a last component for getting to a fossil-fuel free grid, particularly at high latitude.

sparkie 6y ago
But this is missing the elephant in the living room (this thread), which is nuclear. One of the main issues with nuclear is that it isn't cost effective to turn on/off to meet demand changes in day and night. Nuclear power stations usually only generate energy for the baseload. If we were to cut energy consumption down at night (by increasing costs), the baseload would also drop, and leave an even larger gap to meet for peak, which must be met by other means like solar or fossil fuels. If anything, we want to shift some energy consumption to off-peak times like early hours, so that the baseload is higher and can be met by cheaper nuclear, along with other solutions like tidal. If this happens, the gap between peak and baseload during the day/evening will be smaller, and can be met with solutions like (concentrating) solar which are more environmentally friendly than photovoltaics + batteries.
- pfdietz 6y ago
  No, it's not missing nuclear. Hydrogen is the stake through the heart that kills the last argument for nuclear (that batteries can't handle long term load leveling). With reasonable projections of where the costs of renewables and storage are going, nuclear gets optimized right out of the picture.
  - sparkie 6y ago
    Yeah, I can't take you seriously. GL with your blackouts and energy quotas, oh, and reliance of fossil fuels. Where do you think the energy is going to come from to perform electrolysis for hydrogen? solar? You are nowhere near meeting basic needs yet with solar, wind, tidal, geothermal combined. (3 out of the 4 can be intermittent/dependant on environmental conditions and are not reliable). Remember, energy demand is going to continue increasing. By the time your renewable utopia exists, you're going to need to double or triple its capacity. Perhaps I'm unaware of some technological breakthrough which can produce hydrogen using little energy? Nuclear is great once up-front costs are paid. Most future energy demand will be met by nuclear. Cleaner renewables will be there to provide additional capacity above baseload, but I wouldn't depend on them to meet basic needs. I have pondered whether it would be possible to generate hydrogen more cheaply via concentrating solar or geothermal. The hotter you can get water before performing electrolysis, the less electricity will be required. Above 3k Celsius, the atoms in water will dissociate without electricity. You might have a reasonable argument against nuclear if you don't need to spend 3x the electricity creating the hydrogen than you'll get back from it.
    - pfdietz 6y ago
      > You are nowhere near meeting basic needs yet with solar, wind, tidal, geothermal combined. Ah, the old "it hasn't happened yet, therefore it can't happen" argument. I'm sure if you honestly think about it you can realize why that argument is nonsense. > (3 out of the 4 can be intermittent/dependant on environmental conditions and are not reliable). We're talking here about power for hydrogen production. Intermittency doesn't matter much for that (it requires the electrolysers be cheap, but their costs have plummeted recently, so that's no longer an obstacle.) > Perhaps I'm unaware of some technological breakthrough which can produce hydrogen using little energy? Perhaps you could stop using strawman arguments? Hydrogen doesn't have to be produced with little energy in order for hydrogen storage to be viable. The energy that is used just needs to be sufficiently cheap. You know, like that $0.013/kWh power from large scale PV in the UAE? And that's only the latest in a constant string of record low bids. > Nuclear is great once up-front costs are paid. Yes, if you can get the Nuclear Fairy to wave a magic wand and make the power plant appear for free, it's much less expensive (but even then, the operating costs will be much higher than renewables). In the real world where real money has to be paid to build nuclear power plants, not so much. > I have pondered whether it would be possible to generate hydrogen more cheaply via concentrating solar or geothermal. Neither of these are competitive with PV now. Hell, it's now cheaper to make domestic solar hot water with PV and a resistive heater than it would be to use solar thermal collectors (although a heat pump water heater would be cheaper still). PV has gotten THAT cheap.