Bardo wrote: Fri Oct 05, 2018 2:46 pm
AndyH wrote: Fri Oct 05, 2018 10:28 am
Bardo wrote: Fri Oct 05, 2018 10:08 am
Again, gravity is a battery. Sea water pumped to 10,000 ft in the day and let down to a turbine at night. There couldnt be a better place for it than CA.
There aren't enough high areas to store enough energy. That's the problem with pumped hydro anywhere in the world. That's exactly why Germany's energy transition is using excess renewable energy (that would otherwise be curtailed and unused) to generate hydrogen and methane for storage in the country's natural gas grid. They have enough storage already in place to run the country - from apartments to manufacturing Mercedes trucks - for six months with no additional energy inputs. We can do the same.
https://dothemath.ucsd.edu/2011/11/pump-up-the-storage/
While we’re having “fun,” let’s see what we could get out of the Great Lakes. The upper four lakes are all at essentially the same elevation (6 meter drop from Superior to Erie), while there is a 99 m drop between Erie and Ontario. We call this Niagra Falls, although only half the drop is developed across the falls proper.
If we drained one meter from every upper lake, we would get 54 billion kWh of energy: about a sixth of the target capacity. If performed over seven days, the flow would be 375,000 cubic meters per second, or 125 times the normal flow over the falls. Now I’d pay to see that! But I would first want to visit every town along the St. Lawrence River one last time.
If we tried to trap the water in Lake Ontario so-as to spare those downstream of the wrath, its level would rise 12 meters (39 feet). Watch out Toronto & Rochester!
The pipe delivering this water to the turbines would have to be over 125 meters in diameter (or 160 tubes each 10 m in diameter) to limit the velocity of the water through the pipes/turbines to below freeway speeds! What fun.
Im in no way an engineer or have done any kind of numbers...but if anywhere seemed perfect for gravity battery it would be the peaks of the sierras and the valleys of central california. Controlling flow is pretty easy with valves.
It's not about how easy it would be to use valves. The problem is that we need really huge amounts of storage and the cost to carve CA's mountains into lakes (in money, the environment, and maintenance) is even larger - and even then it's nowhere near enough. The post above - the piece about using the Great Lakes - is important. Start with
the area of the lakes he's using:
Superior: 31,700 square miles
Michigan: 22,300 square miles
Huron: 23,000 square miles
Erie: 9,910 square miles
Total: 86,910 square miles
Put a map of the 'upper' Great Lakes over the Sierras. Install all the pipes. Then realize that
it would only provide 1/6 of the storage we need while also reducing the snow and ice storage CA uses for some of their summer water supply. That's why pumped storage is a non-starter.
ETA. Here's a real-world example. Here's an island trying to get 100% renewable. Engineers designed the pumped storage system to do the job. The problem is, even though they have more generation than they need, the pumped storage system isn't working well enough and they still have to burn diesel to fill in the gaps.
https://www.hydropower.org/blog/case-st ... nd-systems
https://www.researchgate.net/publicatio ... rro_Island
(The good news? If we implement either the Third Industrial Revolution plan, or RMI's Reinventing Fire plan, we won't need a ton of storage. That's useful because once sea level rises, California's gonna need their mountains.
)