[Graeme]

Wiki suggests that the most economical way to utilize unused grid electricity is to find an alternative market using HVDC.

[kublikhan]

It seems to me an even cheaper option would be to just use exisiting coal/natural gas plants as a stand in for solar/wind power. As we build up more solar/wind, shutdown existing coal/natural gas plants. Then start 'em up again when solar/wind die down or demand spikes up. Australia is already doing this with some of it's coal plants. Natural gas is a good contender as well as it can rapidly cycle up/down.

Also, Solar PV is especially good at following the demand curve. IE, it produces the most power when demand is highest. Reducing the demand for new peaker plants.

Graeme's solution is high on my list as well. Build new grid interconnects so we can balance surplus/shortages across our regional electric grids and/or neighboring nations. Germany does this, exporting surplus wind/solar energy and importing energy from it's neighbors when supply falls short or demand spikes up.

$this->bbcode_second_pass_quote('', '[')b]Backup for Renewables
One area where natural gas excels is as a back up for intermittent renewable energy, since it can ramp up and down quickly. So this is one area where a person might expect growth.
....

A grid that has ample off-peak generation will find addtional coal or nuclear to have zero value during those hours. At the same time it can find solar to be very valuable as it provides peak hour power, off-setting expensive peaking generation. Additonally solar production highly coorrelates to increased demand from air conditioning.

A few years back it was found that the US grids could convert to 25% (eastern grid) to 35% (western grid) wind and solar without adding any fill-in generation or storage.

Since that study was completed we have cut our coal generation from 49% (2006) to under 40% (36% for first half of 2012). We have replaced a good piece of that 13% total with dispatchable natural gas. Our generation from NG has risen from 20.1% (2006) to 31% (first half 2012).

That means that we could boost the 25%- 35% by at least another 10%, using the extra NG geneation only when the Sun was not shining and the wind not blowing.

All of the US grids could be more than 1/3rd wind and solar without requiring us to build a single gas plant.

As we move from a fossil fuel grid to a renewable energy grid we will call on fossil fuels at time. For example, Southern Australia has closed some of its coal plants but put one in mothballs for use during times of the year when demand is the highest. Gas plants will likely see some service for decades, first as everyday fill-in and later as 'last player' reserve.

[Newfie]

The problem is not technology. I'm not sure there is a technological fix for the fix we are in, but stipulating so for the sake of argument, the problem become our inability to utilize the fix.

HVDC is a prime example. No reason to not do it. Congress even has the special power to force grid right of way. It save nearly 30% of transmission loss, existing infrastructure is in a bad way and need redo anyway.

Yet we fiddle.

[sparky]

.
A compressed air/water device exist exactly in the opposite direction
rather than having gravity storage for water tower
for esthetic reason and height restriction there is a system of a big pressure vessel where the water is pumped in a closed reservoir
it act as a dampening for main pressure fluctuations