dmcmahon wrote:. The best storage technology in use today is pumped hydro - you need a convenient dam/reservoir somewhere to buffer your excess power. Wind power leader Denmark effectively uses Nordic hydropower as their "battery". It's a good solution (about 70% efficient) until you reach the limits of your hydro capacity - but then what? The UK is confronting this reality now as it tries to craft a lower-carbon energy policy for the next few decades. Solar thermal plants aren't as efficient as PV, but there is the potential to bank energy in "thermal mass" (e.g. a molten salt) - this technology can't really be called "commercialised" yet. Without a solution to power storage, renewables will only take us so far before the grid becomes unstable. Demand shifting could potentially get us a bit farther. After that, we need to be honest about where baseload power is going to come from, especially since that power is likely to be what goes into any EVs. Right now, at least in the USA, half of it comes from coal. We could switch away from coal to nat gas, or to nukes
.
Lots to reply to on the transport side.
But let's look at wind. The wind goes through 'lulls' but they are anything but continent-wide, and long distance DC power is widely used (less in USA, but widely used everywhere else). Just because Texas is cut off from the rest of the US grid, is not an argument that Texas cannot have more than x wind power because during heat waves Texas doesn't get much wind-- the ERCOT separation from the US grid is deliberate and could be altered. And the wind cycle just offshore in Texas is different.
Offshore wind is on its own cycle, and 150' above the ocean the winds are a lot more constant than they are at sea level.
On pumped storage you don't 'run out of' hydro. The UK is in North American terms basically flat (highest peak something like 1800 feet) and we have major pumped storage facilities. the problem of local fights over flooding valleys is more serious. And the Canadians are looking at using mines to do this-- drop the water down when you need it, pump it up when you have spare capacity.
And there is still compressed air, flywheels, fuel cells, hydrogen etc.
All technologies have their downsides. Nuclear is not despatchable in grid terms either: nuclear shutdowns are either sudden and unplanned, or happen for weeks on months. That's not so very different from a diversified portfolio of wind assets.
Solar is of course almost entirely predictable (bad weather causes production to drop, but not drop to zero).
Whether we can get wind over 50% of kwhr from wind is an interesting point. The National Grid in the UK is on record as saying it could take c. 40%. After that your requirement for backup gas turbines starts to grow very quickly. But we are aiming for 40GW+ of wind capacity, and that would imply at least 15% of all electricity burned.
yes the UK is confronting all this. The dynamic to go nuclear however is largely political and will involve a 'fix' on the electricity market to guarantee high enough prices for the plants to get built. So much for 'free' electricity markets. And it's unlikely the 10 plants (about 20% of total demand) will all get built: one of the big utilities has just pulled out. At least not without further intervention via loan guarantees from the UK government. We'll probably build 4-6 plants and by that time the ever falling cost curves of renewable energy (plus Carbon Capture and Storage) will pick up the slack. And none of those nukes will be running this side of 2020 it doesn't look like.
Gas their seems to be a lot more around that we thought but we'll still need CCS on it. Coal is the low hanging fruit on CCS, but gas will also require it.
(roughly speaking, coal take you from 1kg CO2/ kwhr, gas to 0.5 kg/ kwhr, and CSS will take you down below 0.1 kg/kwhr).
In essence in chasing the nuclear chimera the UK wind up 80% gas, and then wind will pick up the slack. Ocean power as well (the decision not to build the Severn Barrier is wrong, as that would be c. 8% UK power consumption, but I don't expect it to be revisited for a decade or two).
The 'realist' view that it can't be done by renewables (plus CSS) ignores the 'unrealistic' problem that nuclear cost inflation is severe (and post Fukushima will get worse), the waste problem is still not solved. As to coal, well it's essentially a crime against the future to build a coal plant without CSS, and eventually (in 20 or so years) I suspect it will become impossible-- utilities are already beginning to worry about the liablity issue.