Re: Guardian: Solar power from Sahara could provide Europe's electricity, says EU

On Wed, 23 Jul 2008 10:56:02 -0700 (PDT), Mel Rowing
<mel.rowing@xxxxxxxxxxxxxx> wrote:

On Jul 23, 6:32 pm, Steve Wallis
<revolutionarysocialistst...@xxxxxxxxxxx> wrote:

The grid proposal, which has won political support from both Nicholas
Sarkozy and Gordon Brown,

Endorsement indeed!

answers the perennial criticism that
renewable power will never be economic because the weather is not
sufficiently predictable. Its supporters argue that even if the wind
is not blowing hard enough in the North Sea, it will be blowing
somewhere else in Europe, or the sun will be shining on a solar farm
somewhere.

This is perfectly true but think of the duplication involved.

The reality is that even in the Sahara the sun shines only 50% of the
year and even in the remaining 50% probably for 10-20% of the time it
is probably so low in the sky to be of only limited use. This will
mean extra conventional capacity being held in reserve. Critics to
this point of view always point out that this reserve exists anyway.
They are in confusion with the requirement to hold mainly "spinning
reserve" so as to ensure continuity of supply. That will be necessary
in addition.

Windmills, photovoltaics, solar furnaces will be fine so long as their
output can be stored in some way either through the production of
hydrogen or pumping water against gravity. However, as regards being a
primary source of electricity for the public supply either will be
expensive or precarious. There is no way they can be neither.

I like the idea of a flywheel that is spun up once, on installation,
then kept spinning during daylight by means of solar energy. The
flywheel is then "tapped" for energy when the sun isn't shining.

Another approach: Use solar energy to pump water (in a closed system,
so that the same water is used over and over again) to a tank mounted
high above the ground, then use the power of the water to drive a
turbine when the sun isn't shining.

MM
.

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