[ExI] The silent PV revolution

[Eugen Leitl]

On Fri, Mar 30, 2012 at 02:01:36PM +0200, Alfio Puglisi wrote:

> > Large scale electrochemical storage is coming.
> 
> 
> What is the form of this storage? I thought that batteries (li-ion or
> whatever) couldn't be scaled up enough.

For one we have a recent revival of putting peak into hydrogen
(PEM water electrolysis) and methane (Sabatier) which can be fed
into the existing natural gas infrastructure (mixes 5-15% without
changes in infrastructure), with ability to buffer (Germany up to 
3 months). This will become critical as renewable input will
rise faster than the grid can absorb it, particularly during
peak (think sunny and blustery day across much of Europe --
use it, or lose it).

Notice that both hydrogen and methane are not just useful as
energy carriers, but are also critical inputs into industry (e.g. metal
oxide reduction), high-temperature processes, synthetic input
(e.g. methanol from CO2 and hydrogen), air nitrogen fixation
and the like. Many people seem to think that electricity is
the only thing that counts -- nothing could be further from
the truth, though degree of electrification *will* increase,
doubling to tripling the current electricity usage.

Further there are new developments in large scale (>>MWh) batteries
based on lithium iron phosphate, zinc-air, liquid redox flow 
and molten metal/salt batteries based on abundant elements
and materials. Potentially lower power density and weight is 
irrelevant for grid buffer applications.

For home and vehicle (peak cache) uses I do think that newer 
electrochemical supercapacitors which manage NiMH-like energy 
densities yet allow very large number of cycles would become
intesting. Also, the same batteries that are being used in EVs
could handle homes.

I have no idea which particular technology will win, long-term.
As I've said multiple times, we're unnecessarily late in developing
these basic processes. Starting in 1970s would have given us
usable technology in a suitable time frame. Now, we have to rush.