I want to thank Richard Katz for his thoughtful and extensive discussion regarding renewable energy. Alex Luta already did an excellent job addressing some of the points he raised, so I will not focus on those points, except toward the end of this post. First I want to focus on one issue Rick raises where I feel well placed to contribute some knowledge, namely electricity storage. According to RK:

"Then there is the scientific problem of electricity storage. These problems are not easily overcome just by making today's solar cells more cheaply."

I interpret this passage to mean that fundamental and uncertain scientific advances are needed before we can store electricity, and because we cannot count on such advances this is another reason not to rely on renewables. In answer to this I will show that electricity storage is, strictly speaking, not necessary for renewable energy to replace nuclear in producing 30% of Japan's electricity within the next 25 years, that Japan already has significant electricity storage capacity, and that there are at least two major storage technologies available today that are already being used and only need to be scaled up until increasing economies of scale kick in.

Electricity storage is not needed for Japan to reach the modest goal of producing 30% of its electricity from renewables because today wind and solar plants are backed up with natural gas generators (natural gas generators are the fastest and cheapest fossil fuel
backup) that kick on when these renewables electricity production dips. This is not an ideal solution to be sure, and this method would by definition prevent renewables from producing 100% of Japan's electricity (the limit would probably be somewhere between half and two-thirds of Japan's electricity production), but as 30% is such a modest level, renewables could easily supply an average of 30% of Japan's electricity using this method alone, and without relying on storage.

Second, Japan already has substantial electricity storage capacity in the form of pump storage hydro:
25.5 gigawatts, or nearly a quarter of global capacity.
Moreover, Japan can use its conventional hydro dams for electricity storage as well: electricity production can be increased and decreased as renewable production falls or rises (and there tends to be a complementary relationship between the availability of solar and
hydro: sunny hot days tend to produce less hydro potential, and cloudy rainy days produce less solar energy).

Third, and most importantly, there are two other commercially used technologies available today for electricity storage that only need to be scaled up:
flywheel storage and hydrogen storage. Flywheel storage involves storing electricity as kinectic energy inside of a vacuum cylinder where a flywheel spins.
Solar and wind power the flywheel, and when its energy is needed it in turn powers a generator. Flywheel storage has been in use commercially in the US for the last few years. Beacon Power runs a flywheel plant for the grid in New York state and is preparing to build a second plant in Pennsylvania.

The second technology involves storing electricity as
hydrogen: renewable energy powers electrolysis to make hydrogen, this hydrogen is stored, and when needed, is used to power fuel cells that produce electricity. How revolutionary are these two technologies? Both electrolysis and fuel cells are mid 19th century technology. Of course, both have developed considerably since then (I have seen the advances that Japanese-Norwegian groups are reporting in this area, especially for cars), but there are no significant technological hurdles to employing these technologies to store renewable energy in the form of hydrogen for the grid. Indeed, fuel cells have been widely used commercially for a long time: the Space Shuttle, many satellites, remote light houses, forklifts, etc. What is needed is product development to scale up to a level needed to provide significant storage capacity for the grid, and investment to put hydrogen storage infrastructure in place and realize economies of scale.
Germany already has a number of pilot projects under way that provide hydrogen storage of electricity.

This brings me to the last paragraph of Richard Katz's most recent post:

"Personally, at present, I'm inclined to see nuclear as a bridging technology until renewals are ready for prime time. I'm for subsidizing renewables, particularly research to accelerate their commercial feasibility, but the amount of subsidy needs to have some reasonable limit, as does the pacing of their introduction.

What strikes me about this passage is that although RK seems to be ostensibly challenging the Noda administration policy, his position is pretty much their policy: gradually phasing out nuclear power while gradually phasing in renewables over the next quarter of a century. On the other hand, renewables are way past the stage of basic research (although new and better forms are constantly under development).
What they need for "commercial feasibility" is to realize economies of scale through broader adoption, and that is something basic research cannot achieve.
This is why mechanisms like the Feed-in-Tariff makes sense.

The main problem with the German Feed-in-Tariff to date is not that it has been too optimistic (cost overruns are impossible by definition, since those who cannot produce at the gradually-falling subsidized price provided are left to go bankrupt), but too pessimistic.
The cost of renewable energy has dropped much faster than the designers of the FIT imagined, and consequently those investing in this area have been realizing wind-fall profits. As a result Germany slashed its FIT subsidies for new renewable capacity this year by 20-30%, and eliminated them altogether for solar PV plants producing more than 10 megawatts, as the later had already reached market parity. They did this, even though the average family has only been paying approximately 4 Euros extra a month in electricity rates due to the FIT. Here is another indicator of how competitive solar has become: solar electricity is estimated to have cut peak summertime wholesale prices in Germany by as much as 40% compared to prices before the advent of large-scale solar:
http://www.crikey.com.au/2012/03/27/why-generators-are-
terrified-of-solar/

Regarding Japan and its FIT, the level of subsidy may well have been set too high, but the difference with Germany undoubtedly reflects, in part, Japan's higher electricity rates. As I wrote earlier, the way to deal with Japan's high electricity rates is to break up the de facto regional electricity monopolies by divesting them of the grid and allowing competition via equal access to the grid for Japanese and foreign suppliers.
The other thing Japan should do is adopt more rational pricing policies: users, especially large scale users, should have to pay a lot more when they use electricity at peak demand, and reward users with cheaper electricity when demand is low. If Toyota wants the absorbent priviledge of producing cars on a hot weekday afternoon in August, it should have to pay the absorbent cost, but if it wants to produce cars on a Sunday morning in May it should be rewarded with dirt cheap power. The lack of effective congestion or peak charges is one reason why electricity is so expensive in Japan. With more rational pricing there will be less need to subsidize renewables.

Then again, if installed solar electricity capacity surges thanks to Japan's new FIT, electricity supply will also likely surge on hot summer days (as is already happening in Germany), easing the very danger of shortage that was used to justify restarting the two Oi reactors this summer. Indeed, one reason for why we now know that the Oi reactors did not need to be restarted to prevent a shortage is because solar electricity production exceeded government estimates by 67% (Asahi Shimbun, September 5, 2012).

Paul Midford
Norwegian University for Science and Technology