[ExI] Comment for Scientific American

John Clark johnkclark at gmail.com
Sun Oct 4 17:25:32 UTC 2015

On Sun, Oct 4, 2015 at 10:55 AM, Keith Henson <hkeithhenson at gmail.com>

​> ​
> I am not particular as to which way we replace fossil fuel except that
> ​ ​
> it needs to be less expensive.

I don't see solar power satellites providing energy cheaper than fossil
fuel anytime in the immediate future, to me even terrestrial solar and wind
seem too dilute and intermittent to compete with coal economically. The
only fuels I
​can ​
​of that ​
have a chance to beat coal in both the short term and the long are Uranium
and Thorium. In the case of Thorium by long term I mean billions of years,
and Thorium reactors are the very opposite of dilute, they run hotter and
​ thus ​
more efficiently than Uranium reactors.

​ John K Clark​

I wrote this as a comment to "Climate Model Shows Limits of Global
> Pollution Pledges" on the Scientific American web site.
> Alas, the comment system seems to be down.
> If anyone sees a good place to post it, welcome to use some or all of it.
> Keith
> Why is it so hard to get agreement about cutting CO2?  The
> consequences of not doing so are clearly bad.  We expect weather
> disruptions and rising sea level to cause awful problems in the
> future.  But those problems are in the relatively long-term future.
> Sharply reducing the CO2 output will cause huge problems in the
> near-term future.  Reducing CO2 emissions will cause the cost of
> energy to rise, and anyone who remembers 1974 knows what that does to
> the economy.  Governments are not going to cause their economies to
> crash in the short term to cope with a long term problem.  Most of the
> people who are in power today count on being gone to the grave before
> the "CO2 chickens” come home to roost.
> So what could we do?  The only way that I can see that makes sense is
> to find a cheaper replacement for fossil fuels.  The current
> candidates--PV solar and wind--are too expensive, too limited or both.
> They both require very expensive storage.
> Nuclear is carbon free (more or less).  It won't last forever, but it
> would be good for a number of decades to centuries.  If we can solve
> the cancer problem (which seems likely) we can put up with an
> occasional meltdown.  It takes about 15,000 one GW reactors to
> displace fossil fuel.
> Two ways (at least) might be able to get the cost of solar down.  One
> of them is StratoSolar where you put the collectors on buoyant
> platforms at 20 km and use massive weights (gravity storage) to supply
> power at night.  That high, you never are troubled with clouds making
> sunlight completely predictable.
> The other is solar power satellites.  Invented in 1968, they have seen
> a lot of study, but the economics just didn't work.  With recent
> developments in low cost transport to LEO and low-cost, beamed-energy,
> electric propulsion to GEO they could provide electricity about 25%
> cheaper than coal.
> It would take about 3000 five GW power plants in GEO to displace
> fossil fuel with less expensive, abundant energy from space (and there
> is room for a lot more).  On a fast track humans could be off fossil
> fuel soon enough (early 2030s) to keep the temperature rise down.
> Further, with oceans of cheap energy, we could take CO2 out of the
> atmosphere to any level we want.
> I am not particular as to which way we replace fossil fuel except that
> it needs to be less expensive.  If there was a less expensive source
> of energy, there would not be concerns or the need for international
> agreements.  People would just quit using expensive fossil fuel and
> switch without being forced.
> Examining low-cost, no carbon energy solutions is not part of the
> mandate of the IPCC.  Perhaps it should be.
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