[clug] OT: Solar power recommendations and advice

Paul Wayper paulway at mabula.net
Tue Apr 20 05:16:52 MDT 2010

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On 20/04/10 18:22, felix.karpfen at gmail.com wrote:
> The main problem with electricity (AC current) is that it cannot be
> stored. This holds true both for solar panels (after conversion to AC)
> and for power-stations. Power stations that are based on hydro-electric
> power can just use their unwanted electricity to pump water uphill, back
> into the reservoir. Other power stations (and domestic producers) hook
> up to a grid and hope that someone, somewhere will use that electricity
> and pay for it. When electricity production from non-fossil-fuels
> becomes sufficiently high (and price-competitive) the demand for
> conventional-power-station-generated electricity will drop;. Until such
> electricity generation reaches a point at which commercial (fossil-fuel)
> producers are forced to shut down some of their generators - part-time
> or totally - the greenhouse gases that they pump into the atmosphere
> will not get any less.

We agree on all but the last sentence.  As far as I'm aware, most power
stations consume fuel in rough proportion to the power they produce.  So a
coal-fired power station generating 100MW would produce about twice the waste
compared to if it was generating 50MW.

There's a minor technicality there - power stations can't just ramp up power
linearly.  Each generator will have a point at which it generates power most
efficiently and this efficiency will reduce as you go higher or lower than
that point.  So for a power station it's probably better to run five 10MW
generators at their optimum efficiency (let's say 10MW) than run ten
generators at their less efficient 5MW.  Each generator set takes a while to
get up to speed - for a big turbine this can be a matter of hours, as you have
to wait for everything to heat up evenly otherwise things tend to burst - and
cool down is a similar time.  But I say this is a minor technicality because
the power companies work hard to produce power optimally; they'll be choosing
what selection of generators they'll use over time to get good efficiency.

Therefore we can assume that as we turn off the stadium lights, or switch off
our lights, this directly contributes to reducing the greenhouse gas
emissions.  Obviously, making long-term choices such as changing electric hot
water for solar or heat-exchanger water heaters, or replacing ones
incandescent bulbs with fluorescent, or replacing one's quad-core 600W
computobeast with a dual-core 50W laptop, are going to make differences over
time too.

One thing you've said resonated with me.  That is that I think we all have to
act on this.  We can't wait for governments to enact emissions trading schemes
or businesses to turn off their building lights at night in order to reduce
power.  Each of us can do this.  And when we do, and we spread the word of
what we're doing (e.g. on this list), we convince other people to act.  Like
advocating FOSS over proprietary software, each person does what they can in
their own work and home environments and gradually the word spreads until
everyone does it.

Me, I can't wait to see the last coal-fired power station turned off. :-)

Have fun,

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