Wednesday, April 20, 2011

Filling the power vacuum in Japan

I mentioned that there were a couple of hurriedly-arranged sessions on the Tohoku earthquake and tsunami at the EGU. Well, we were basically twiddling our thumbs for the last couple of days before leaving for Vienna - the computers were off due to the power cuts, and our posters had been printed - so we thought we might as well chuck together another poster to take with us for this new session. While most people were naturally focussing on the geophysics, our particular perspective was on the potential for solar power generation - especially if promoted by the Govt - to fill the gap left by the shut-down of Fukushima power plant (and others, though they will probably come back on line sooner or later). Current projections are that the peak summer production will be about 45GW in the TEPCO area, but the usual demand is...60GW. Meaning that the power cuts (which are in abeyance for now) will be back with a vengeance in a a couple of months, and might take place next summer too. So everyone is desperately looking for ways both to cut consumption and to find new resources.

Our poster is here (warning - 5MB). A few quick calculations suggest that a sustained push for installation of solar power could make a significant impact. Firstly, although I didn't actually find a precise statistic for total production capacity, it seems that Japan makes several GW of solar panelling per year (one factory alone makes 1GW). Also, Japan builds a ridiculous number of houses each year - over a million, about the same as the (much larger) USA. So there is a lot of new roof space under construction, and it may be reasonable to expect that build-integrated solar power could probably add about 2.5GW of capacity per year in the TEPCO area.

These capacity figures are all peak rather than average power, and the typical problem with solar (that makes it relatively expensive at least on a capital cost basis) is that it only generates power part of the time. A typical capacity factor is 15%, meaning that a 1kW panel will generate not 24kWh per day but more like 4 - or conversely, you need to build and install 7kW of panelling, and a storage system, to get an average 1kW output. But here's the key insight - the Japanese power demand peaks precisely when the solar power is actually producing, during summer daytime hours. So since the current concern is not the total power production, but rather the summer daytime peak, solar is suddenly a rather attractive solution. In fact the capital cost seems to be not far out of line of other more conventional power supplies, at maybe $5 per W (peak). Right now, it's also a distress purchase - if people want their A/C on during the summer (which I certainly do) then the price may not be a primary factor.

Apparently the Governor of Kanagawa (our prefecture) is pushing for solar power, and the national govt also has a policy goal of 30% by 2030. So it will be interesting to see what, if anything, happens.


EliRabett said...

True, but the peak for solar also is the peak for electrical demand (summer days) and nuclear (ok, now a no no) is great for baseload.

James Annan said...


That was our point! We already have enough now to cover the base load (though perhaps not in the most cost- or carbon-efficient manner).

Anonymous said...

Australia is in a similar position. They can spend billions on a baseload powerstation, that will effectively be sitting idle for most of the year, just to cope with the very hot days when the sun is shining at it's brightest.

Or, they can subsidise solar panels for individuals, which is exactly what they have done. It is expensive, and they are cutting back on the scheme in these economically 'hard' times. If anything, the scheme has been too successful, with far more people lining up to buy panels, and blowing the budget. The panels are a common sight now on house rooftops.

It will be interesting to see how the figures work out in a few years time, after some more hot summers. La Nina has just given many cities a cooler and wetter summer than usual.


James Annan said...

In the poster session, we had a bunch of comments from Germans (being in Austria and all) who have a lot of solar panelling these days and were rather sceptical as to its value. But of course a lot of their demand is for heating in winter, when it's dark and cloudy...

Japan used to have a subsidy scheme a few years ago, which was popular but (therefore?) has been discontinued. If the alternative is factory shutdowns and residential power cuts then that rather changes the whole climate.

EliRabett said...

It's windy as hell in Germany in the winter. Every damn farmer has a wind mill