Thermal (cryogenic):

http://isentropic.co.uk/
http://www.highview-power.com/wordpress/?page_id=1320f
http://www.rwe.com/web/cms/en/365478/rwe/innovation/projects-technologies/energy-storage/project-adele-adele-ing/

Electrostatic (solid-state supercapacitors) :
http://cleantechnica.com/2013/03/12/a-breakthrough-in-energy-storage-graphene-micro-supercapacitors/
(hey, that was published here!)

Electrochemical, power-to-gas for seasonal storage:
http://www.zsw-bw.de/en/support/press-releases/press-detail/weltweit-groesste-power-to-gas-anlage-zur-methan-erzeugung-geht-in-betrieb.html

And, for when there’s surplus renewable power and to displace fossil fuels and environmentally-questionable biofuels in applications like aviation and seafaring (or even some land transport in the shorter term) where batteries and overhead catenary transmission of electricity don’t quite cut it:
http://www.carbonrecycling.is/
http://www.dotyenergy.com/

IBM and other companies are working on zinc-air batteries. But if we go with lithium-ion there is no shortage of lithium. We’ve got lithium here in the US, right now we’re getting ready to extract it from Salton Sea geothermal waste water.

Additionally we could extract all the lithium we would ever need from ocean water and add only a modest amount to the cost of EV batteries.

No one has been able to get the weight of ultracapacitors down to an acceptable level to date. It’s possible we would see hybrid battery UC packs for EVs as UCs can take a quick charge and would be great for regenerative braking.

Interesting things are happening in storage batteries. I suspect flywheels won’t be where we go if promising battery tech pans out.

Another idea I heard for individuals homes would be inertial rather than chemical energy capture: using daytime solar energy to spin massive rotating drums at very high speeds under low-friction conditions, thereby giving the drums enough rotational energy to generate electricity through the night.
(I think this would be a very cool and interesting shift towards a garage-inventor-style energy grid)

” The price of electricity is moving in only one direction: steeply up. ”
The price of electricity produced by solar panels is heading down, rapidly.
Even if solar doesn’t always make electricity cheaper, decreasing the rise in electricity prices is a good thing….

There seems to be a range of opinion about that.

The price of electricity is moving in only one direction: steeply up. For the Krefeld plant, the cost of a kilowatt hour of electricity has tripled since 2000.
…
According to a recent survey by the DIHK, almost one in five industrial companies plans to shift capacities abroad — or has already done so. The study also finds that almost 60 percent fear power outages or voltage fluctuations in the power grid, because wind and solar power are still too unreliable.

http://www.spiegel.de/international/business/0,1518,816669,00.html

Or maybe not. According to the first graph of the IZES study, 2011 prices were substantially higher than 2007 prices — 50-60 E/MW-h vs. 30-40 E/MW-h.
http://www.solarwirtschaft.de/fileadmin/media/pdf/120131_Pr%C3%A4sentation_Preiseffekte_von_PV.pdf

“Additionally, as noted above, peak demand isn’t at night, and what solar is most useful for (at the moment) is covering peak demand. …”

According to ENTSOE, peak demand in 2011 was in the evening during the winter months, over 80 GW, of which roughly 0% was provided by solar. In the summer months, demand peaked in midday at about 75 GW; solar was a pretty good match for that. Given the seasonal variation, it’s probably a mistake to lump the whole year together.
https://www.entsoe.eu/resources/data-portal/consumption/

“Solar power from Germany is sometimes exported and electricity from other power sources is sometimes imported.”

I was surprised to find that Germany exports power in the winter, despite higher demand around the clock — about 3 TW-h per month, net. In the summer, imports and exports are balanced. (Or were until last year, when its net exports were down about 1 TW-h/month after March.)
https://www.entsoe.eu/resources/data-portal/exchange/

“Germany’s solar policy has been a wild success.”

If the goal of the policy is to get large amounts of solar capacity, yes. But if the goal is to have “a tremendous, positive impact on CO2 emissions”, not so much.

In Germany, solar is by far the most inefficient technology among renewable energy sources, and yet it receives the most subsidies. Some 56 percent of all green energy subsidies go to solar systems, which produce only 21 percent of subsidized energy.

… To avoid a ton of CO2 emissions, one can spend €5 on insulating the roof of an old building, invest €20 in a new gas-fired power plant or sink about €500 into a new solar energy system.
…
For a time, it seemed that at least the German solar industry was benefiting from the generous subsidy rates. But the green economic miracle has, in the case of the solar industry, turned out to be a subsidy bubble.

http://www.spiegel.de/international/germany/0,1518,809439,00.html

Worth noting.

“A Day in the Life of the Grid

July 21, 2011 is a day that will live in infamy.

Not really. But it was the hottest day of the year in the Midwest and the Midwest Independent System Operator (MISO) territory, which spans 13 states, has 140,000 megawatts of generation under its control, and sells $27 billion of electricity per year.

And on this particular day in July, the region would experience a new peak of 104 gigawatts.

Wellinghoff gave an hour-by-hour status of the MISO region with imaging help from ABB’s Ventyx Velocity software. He looked at the impact on big-box stores, aluminum smelters, data centers, and electric vehicle charging. He noted that consumers are paying $0.09 per kilowatt-hour despite the wholesale rate ranging from $0.00 to $1.00 per kilowatt-hour.

2:00 a.m.: Despite low energy prices across the region, there is no rate incentive for consumers to charge their electric vehicles at this time of day. Electric vehicles could provide regulation service — if they could participate in the market, according to Wellinghoff.

3:00 a.m.: Prices are near zero.

4:00 a.m.: Wind resources are still trapped in the western portion of the region because of transmission issues. The average wholesale energy price is about $0.023 cents per kilowatt-hour. At this time, an EV could charge at 40 cents per gallon gasoline equivalent, according to Wellinghoff.

5:00 a.m.: People in Detroit are waking up, and as power ramps up, pricing starts to rise.

7:00 a.m.: Wind starts to ramp.

8:00 a.m.: Trapped wind prices rise in constrained areas, but 100 miles away, prices are 10 cents per kilowatt-hour. The grid has generators inefficiently ramping-up when it would be more efficient for customers to change their loads. Wellinghoff said that this is an inefficient way of operating the grid.

9:00 a.m.: MISO declares a maximum energy event.

9:35 a.m.: Frequency on some lines drops to 59.964 cycles.

10:00 a.m.: Wind “is falling off a cliff” but ramp is rising. Peak wind is 3 gigawatts less than the previous day.

11:00 a.m.: High prices above $0.10 per kilowatt-hour start to hit the system as imports from PJM dry up.

12:00 p.m.: The wholesale markets are indicating the true costs of energy but there is a disparity between the wholesale price and the price the customer is paying.

1:00 p.m.: The temperature is 100 degrees but wind is down to 1 gigawatt. Only 1,800 of 30,000 turbines are producing power.

2:00 p.m.: Maximum energy warning declared.

4:00 p.m.: PJM sets an all-time peak record of 160 gigawatts while wind drops to a low point. There is a west-to-east price shift that shows a need for transmission build-out.

5:00 p.m.: The maximum energy event is terminated, but people are still making energy decisions with no knowledge of real-time electricity pricing.

6:00 p.m.: Temperatures are starting to cool off in the Midwest and prices have halved.

7:00 p.m.: Higher temperatures are holding firm in some areas and keeping the supply-demand balance tight.

8:00 p.m.: The heat index near the Lake Michigan shoreline and in eastern Michigan drops and demand falls.

9:00 p.m.: Streetlights come on and generating resources go down. MISO brings on more expensive power.

12:00 a.m.: The system becomes unconstrained as the load continues to drop.”

http://www.greentechmedia.com/articles/read/A-Day-in-the-Life-of-the-Grid-with-Jon-Wellinghoff-Chairman-of-FERC/

The first thing I thought when reading that was “Dude! Where’s your solar?” Hot day and wind goes down, that’s no surprise. However with the upper Midwest’s long summer days solar would be pumping out the power.

Because they don’t have solar input they are paying as much as $1/kWh to purchase power.

And take a look at the cost of ‘fueling’ an EV – $0.40/gallon late at night when most EVs would be parked and plugged.

I have thought about that a bit at the occasion of reading this, and came up with another point. Solar peaks at day, when most energy is needed. And it also peaks in summer (in places where there are differences between the seasons).

Now, remember that with global warming, winters will on average become milder and summers hotter. The last winter was mild in Europe as well as in the U.S., leaving natural gas reserves full and prices low as a consequence.

That of course means that one would want to peak solar in summer rather than in winter, as it helps to deal with added demand from global warming, as opposed to peaking in seasons where energy demand will go down as a consequence.

And air conditioning in summer will always be most necessary when there is much sun.

Today peakload & baseload prices have been the same, as solar & wind power covered almost the entire daytime increase of demand.

(EDIT)
Thanks Hermann Scheer.
Unfortunatly we are now in the struggle between:
-Fast & slow transformation
-decentralized & centralized renewable generation

Here’s what I read in the piece above…

“Lomborg is infamous for denying the need for clean energy action to stop human-caused global warming, and for claiming that scientists’ concerns about global warming are overblown.”

That’s pretty consistent with everything that I’ve read from him over the years. “Sure, there’s a tiger in the yard, but don’t worry about it. It isn’t likely to eat you.”

Of course Lomborg’s now changed his tune. He’s now saying that the tiger is likely to eat us. He just doesn’t have the background to tell us how to avoid it. He’s spent so much time trying to defend doing nothing that he’s not kept up with what we need to do.