Raveen wrote:QUOTE (Raveen @ Feb 21 2019, 05:04 AM) Scotland has had days where they used only renewable energy as I understand it. Not to say there isn't a long way to go, and Scotland has lots of energy resources combined with low population density but the road is there waiting for us to take the steps along it.
One of the problems here (and you can see it in the graph of German power production) is the unpredictability of power generation by renewables. On the link I posted above, on the 11th they generated 42GW from solar+ wind, the next day 23, the next day 33, then 26... stability in your power grid is kind of important.
It's also worth noting that you can't install 100GW of solar panel production and get 100GW out. For example, the installed capacity of solar power in Germany is ~43 GW, which if operated for the 1625 hours (mean annual sunshine hours) would get ~70 TWH while their reported actual generation was ~35 TWH. Assuming pump storage is feasible and is 90% efficient, assuming pump storage is not needed during the 1625 daylight hours, and assuming off-peak demand is ~60GW, the installed capacity for Germany's solar power via pump storage would have to be 585GW.
Wind is better because it can be run longer, but you're still looking at efficiencies of around 20%, meaning that to cover the 60GW off-peak time where solar is not available, you would have to install 300GW of capacity.
Nuclear can run at about 90% max capacity safely (provided you don't, like, hit the plant with a tsunami or something), so to cover the 60GW off-peak time when solar is not available, you would need to install 67GW of capacity.
It takes about 3 acres of solar power to generate 1GWH/year, which translates to about .0002 GW/acre, so getting up to 585GW (excluding pump storage locations) would be 293,000 acers of solar panels, or 1200 square kilometers of solar panels. Compare to, say, Diablo Canyon power generation facility in California (which happens to be close to a fault line) located on a 90-acre facility that has a nameplate capacity of 2.2GW and has historically run at 87% capacity for 30+ years (with no incidents): .02 GW/acre.
Cost of production of Diablo Canyon was ~$13000m, which means startup costs are about $6800m per GW. Cost of production of Solarpark Meuro was ~$158m with nameplate capacity of 168MW which will operate at the ~12% (more like 10) capacity for a total cost of $7800m per GW. Collgar wind farm, in Australia, cost about $530m for installed capacity of 206MW with projected 40% actual, or $6400m per GW.
