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Frankly, I wonder if we will ever be completely free from fossil fuels. Renewables have a few problems that need solving. What do you do when the sun isn't shi

Frankly, I wonder if we will ever be completely free from fossil fuels. Renewables have a few problems that need solving. What do you do when the sun isn't shining and the wind isn't blowing? Storage would fix that except we don't have a storage solution that scales to the levels we need and is widely implementable yet. What do you do if the sun decides not to shine and the wind decides not to blow for a long time? What do you do when you exhaust your energy stores? The only thing I can think of is restarting the natural gas and coal plants. Fossil fuel plants will have to be maintained (and staffed) as a backup. Nuclear will work too I guess but same problem, maintenance and staff. The only scenario I can see where we rely totally on renewables only is when we have a huge excess of renewable energy generation and a lot of extra energy storage such that it will buy us enough time to look for alternatives if the weather decides to go weird and deny us solar and wind power.

DennisP 5y ago
One solution: build enough nuclear to cover your nighttime load and run that 24/7, add enough solar to cover just the extra load during the day, and for remaining discrepancies with demand use either batteries or load-following by the nuclear plants, whichever is cheaper. A while back MIT had an electric grid cost simulator online, and that was the cheapest fossil-free combination I could find.
- pfdietz 5y ago
  Did the simulator include hydrogen? In many places, hydrogen reduces the cost of a 100% renewable grid, vs. just using batteries for storage.
  - DennisP 5y ago
    Don't remember. Is anyone doing that in production? If so, what does it cost?
    - pfdietz 5y ago
      There is some underground hydrogen storage (used to smooth output to ammonia synthesis, for example), and some hydrogen pipelines (about 1000 miles in the US), and combustion turbines have been available for 30 or more years that will burn hydrogen. So all the parts are available. Electrolyzers need to be sufficiently cheap to work well with intermittent renewables, but their cost is dropping rapidly. Integrating preexisting technologies is the easiest and surest kind of innovation, even if they haven't all been brought together yet. There are cost estimates at the reference link at https://model.energy/ https://model.energy/ , along with projections of future costs.
adrianN 5y ago
Power2Gas scales, it's just a bit expensive right now.
scottLobster 5y ago
The solution to those things is long-range transmission capability and an adaptive grid. The wind is always blowing somewhere, the sun is always shining somewhere, and at least one of those somewheres will have excess in a properly built out grid. None of that is beyond our capability, the issue is getting the will and dollars to build it. The way it's currently going we're organically building small clumps here and there where capital is available with no overall direction. That can work in the long run, but it means the build-up period will be marked with unequal outcomes by region and gluts/shortages.
- worrycue 5y ago
  Where the sun is shining/wind is blowing might be too far away. There are limits to how far we can draw power from technically, economically, and politically. Also other regions need power too so you would be straining their supply - unless you have, again, huge excess in generation capacity.
  - pfdietz 5y ago
    The cost of a simple cycle gas turbine power plant is maybe 4% of the cost of a new nuclear power plant (and combined cycle just 10%), so backing up the entire grid with turbine capacity isn't that expensive. You need fuel for those turbines, but that's where hydrogen comes in.
    - pfdietz 5y ago
      To clarify: I meant cost per unit of rated power output.
- _8j50 5y ago
  I completley agree. Being able to designate remote arid locations for power generation and being able to transmit that power elsewhere will have a huge impact on society and the environment. My crazy idea is high power lasers and satellites reflecting the sun (magnified beam/laser for minimal night sky disruption??) to the other side of the planet. I wish I had the right education to come up with good ideas, if it was up to me there would be arrays of satellites that convert the sun's light to laser or just a focused beam and literally boil the ocean to generate power! (Good thing there are smarter people working in these problems)
cesarb 5y ago
> What do you do if the sun decides not to shine and the wind decides not to blow for a long time? I always see this argument in these kinds of discussion, but does anyone have real statistics as to how often that actually happens? And how widespread these disruptions actually are, keeping in mind that solar and wind power are often distributed over a wide area? (Keep also in mind that, unless there's a solar eclipse, photovoltaic panels can still produce some power even when it's very cloudy, so that might not lead to a total loss of generation.)
- rsj_hn 5y ago
  If you need a grid that has, say, three 9s of reliability (US grid) or four 9s reliability (European grid), then it can only happen for like 15 minutes per year in Europe or 150 min per year in the US. Now if you are only using wind for 10% of your power needs, a 10% drop in wind is not a big deal. But when you are using wind for 30% of your power needs, then the same variability becomes a bigger deal and might start to impact reliability, even though the wind itself is not more variable than before. Same for solar.
- worrycue 5y ago
  Well just last month … https://www.wsj.com/articles/energy-prices-in-europe-hit-records-after-wind-stops-blowing-11631528258 https://www.wsj.com/articles/energy-prices-in-europe-hit-rec... Renewables like solar and wind depend on the weather - which we cannot control at all. Non-renewables have dependencies too like politics and economics but at least it’s something we have some control over. If solar and wind is to completely replace non-renewables, their intermittency is going to have to be dealt with somehow - and huge excess in generation and storage capacity is only way that comes to mind at the moment.
- pfdietz 5y ago
  You can play with designing a renewable + storage system to supply "synthetic baseload" using actual historical weather data at this website: https://model.energy/ https://model.energy/ (The handling of transmission is greatly simplified, but that's ok for what that is.)
pfdietz 5y ago
> Frankly, I wonder if we will ever be completely free from fossil fuels. One way or the other, this is inevitable. There's only so much fossil fuel that can be burned before the environment becomes too hostile for civilization to survive. > What do you do if the sun decides not to shine and the wind decides not to blow for a long time? What do you do when you exhaust your energy stores? Power2Gas gets you to 100% at a reasonable cost. Batteries act as short term storage, with most of the stored energy going through them; the gas provides long term storage and back up generation, with most of the energy storage capacity there (with a much longer average residence time). There may also be room for intermediate storage on the timescale of a week or so (pumped hydro, thermal, for example). Multiple levels of storage like this is analogous to the cache hierarchy of a computer, in that combining different storage technologies with different properties can provide a solution that is better than any of those just by itself.
- _8j50 5y ago
  Even setting aside the environment, there is only so much oil and natural gas. IIRC, there is only enough to last through this century.

DennisP 5y ago

One solution: build enough nuclear to cover your nighttime load and run that 24/7, add enough solar to cover just the extra load during the day, and for remaining discrepancies with demand use either batteries or load-following by the nuclear plants, whichever is cheaper. A while back MIT had an electric grid cost simulator online, and that was the cheapest fossil-free combination I could find.

pfdietz 5y ago
Did the simulator include hydrogen? In many places, hydrogen reduces the cost of a 100% renewable grid, vs. just using batteries for storage.
- DennisP 5y ago
  Don't remember. Is anyone doing that in production? If so, what does it cost?
  - pfdietz 5y ago
    There is some underground hydrogen storage (used to smooth output to ammonia synthesis, for example), and some hydrogen pipelines (about 1000 miles in the US), and combustion turbines have been available for 30 or more years that will burn hydrogen. So all the parts are available. Electrolyzers need to be sufficiently cheap to work well with intermittent renewables, but their cost is dropping rapidly. Integrating preexisting technologies is the easiest and surest kind of innovation, even if they haven't all been brought together yet. There are cost estimates at the reference link at https://model.energy/ https://model.energy/ , along with projections of future costs.

adrianN 5y ago

Power2Gas scales, it's just a bit expensive right now.

scottLobster 5y ago

The solution to those things is long-range transmission capability and an adaptive grid. The wind is always blowing somewhere, the sun is always shining somewhere, and at least one of those somewheres will have excess in a properly built out grid. None of that is beyond our capability, the issue is getting the will and dollars to build it. The way it's currently going we're organically building small clumps here and there where capital is available with no overall direction. That can work in the long run, but it means the build-up period will be marked with unequal outcomes by region and gluts/shortages.

worrycue 5y ago
Where the sun is shining/wind is blowing might be too far away. There are limits to how far we can draw power from technically, economically, and politically. Also other regions need power too so you would be straining their supply - unless you have, again, huge excess in generation capacity.
- pfdietz 5y ago
  The cost of a simple cycle gas turbine power plant is maybe 4% of the cost of a new nuclear power plant (and combined cycle just 10%), so backing up the entire grid with turbine capacity isn't that expensive. You need fuel for those turbines, but that's where hydrogen comes in.
  - pfdietz 5y ago
    To clarify: I meant cost per unit of rated power output.
_8j50 5y ago
I completley agree. Being able to designate remote arid locations for power generation and being able to transmit that power elsewhere will have a huge impact on society and the environment. My crazy idea is high power lasers and satellites reflecting the sun (magnified beam/laser for minimal night sky disruption??) to the other side of the planet. I wish I had the right education to come up with good ideas, if it was up to me there would be arrays of satellites that convert the sun's light to laser or just a focused beam and literally boil the ocean to generate power! (Good thing there are smarter people working in these problems)

cesarb 5y ago

> What do you do if the sun decides not to shine and the wind decides not to blow for a long time? I always see this argument in these kinds of discussion, but does anyone have real statistics as to how often that actually happens? And how widespread these disruptions actually are, keeping in mind that solar and wind power are often distributed over a wide area? (Keep also in mind that, unless there's a solar eclipse, photovoltaic panels can still produce some power even when it's very cloudy, so that might not lead to a total loss of generation.)

rsj_hn 5y ago
If you need a grid that has, say, three 9s of reliability (US grid) or four 9s reliability (European grid), then it can only happen for like 15 minutes per year in Europe or 150 min per year in the US. Now if you are only using wind for 10% of your power needs, a 10% drop in wind is not a big deal. But when you are using wind for 30% of your power needs, then the same variability becomes a bigger deal and might start to impact reliability, even though the wind itself is not more variable than before. Same for solar.
worrycue 5y ago
Well just last month … https://www.wsj.com/articles/energy-prices-in-europe-hit-records-after-wind-stops-blowing-11631528258 https://www.wsj.com/articles/energy-prices-in-europe-hit-rec... Renewables like solar and wind depend on the weather - which we cannot control at all. Non-renewables have dependencies too like politics and economics but at least it’s something we have some control over. If solar and wind is to completely replace non-renewables, their intermittency is going to have to be dealt with somehow - and huge excess in generation and storage capacity is only way that comes to mind at the moment.
pfdietz 5y ago
You can play with designing a renewable + storage system to supply "synthetic baseload" using actual historical weather data at this website: https://model.energy/ https://model.energy/ (The handling of transmission is greatly simplified, but that's ok for what that is.)

pfdietz 5y ago

> Frankly, I wonder if we will ever be completely free from fossil fuels. One way or the other, this is inevitable. There's only so much fossil fuel that can be burned before the environment becomes too hostile for civilization to survive. > What do you do if the sun decides not to shine and the wind decides not to blow for a long time? What do you do when you exhaust your energy stores? Power2Gas gets you to 100% at a reasonable cost. Batteries act as short term storage, with most of the stored energy going through them; the gas provides long term storage and back up generation, with most of the energy storage capacity there (with a much longer average residence time). There may also be room for intermediate storage on the timescale of a week or so (pumped hydro, thermal, for example). Multiple levels of storage like this is analogous to the cache hierarchy of a computer, in that combining different storage technologies with different properties can provide a solution that is better than any of those just by itself.

_8j50 5y ago
Even setting aside the environment, there is only so much oil and natural gas. IIRC, there is only enough to last through this century.