[mythtv-users] [Slightly OT] solar power for all our gadgets

[Simon Hobson]

Jon Bishop wrote:

>Yes and no. I'm not saying everyone should produce ALL their own 
>energy. That would be impractical, and fall right in line with what 
>you're saying... but SOME of the energy - that's easy. It might be 
>that it needs to be a socialized system (oh no, I said the S word) 
>where everyone pays for the electricity that they use, and rather 
>than building huge solar farms in the desert, the utilities take the 
>surplus and offer incentive programs to install solar on rooftops. 
>Instead of lobbying to build huge dams that might have irreversible 
>impacts on the environment, they could use that money to install 
>micro-hydro facilities in every creek and river in the US. Many of 
>these facilities would be on private land, and none of them would 
>disrupt the flow of the water. By doing this, we also gain the 
>benefit of a decentralized grid, and when grid-tied systems are 
>hooked up properly (that transfer switch is very important) with 
>battery banks in many of these people's homes, we won't NEED to 
>build huge nuclear reactors to make up for the energy that we're 
>currently producing from coal.
>
>>Making every individual generate some energy creates huge inefficiencies
>>which, when simplified, translates to making everyone needlessly poorer.
>
>I don't see how you figure that. By having energy placed into the 
>grid WHERE it is BEING USED instead of generating it in Arizona and 
>shipping it over high voltage lines across hundreds of miles, you're 
>reducing inefficiencies in the grid.

In general (and yes, it's a sweeping generalisation), people in the 
electricity industry aren't keen on large levels of embedded 
generation. In small amounts it's "OK", but there are real worries 
about what large amounts of embedded generation will do to control 
and stability. As it is, I believe in the US the main distribution 
system is split (with DC links) to avoid the problem of trying to 
control and keep stable an AC system the size of the North American 
continent (or at least, last time I looked it was like that).

How much embedded generation is tolerable before system stability is 
at risk is something that's "keenly debated" !

So the distribution companies aren't keen as it complicates their 
switching and protection. Generators aren't keen as it either takes 
some of their base load (the most profitable) or makes them vary 
output more, or both. And the people running the grid and responsible 
for it being stable don't like it because it's hard to control.

And there is the detail every pro<whatever> campaigner seems to 
ignore - certainly for wind, for every kW of wind capacity, you need 
a kW of conventional capacity to back it up when the wind stops 
blowing. The usual counter argument is that the wind will blow 
somewhere - but historical figures show that a few years ago, the 
whole of Europe was more or less becalmed for 10 days ! Now, if you 
are a generator, being asked to provide 'back up' capacity that won't 
be called on much, and will be required to cycle a lot, then you 
aren't going to put in the cleanest, most advanced gas turbines 
(about the only technology with the speed of response required) - 
you'll put in the cheapest on the basis that it's not going to earn 
much revenue when it's not generating, and it's not going to last too 
long when constantly cycled. Result ? Wind results in more emissions !

Not saying wind is bad, but you have to think of the WHOLE picture. 
Of course, solar is even worse, you know that EVERY day, all solar in 
the US will stop generating. Just like ALL solar in Europe will stop 
generating a few hours earlier.
So you either have to have storage (and apart from hydro we don't 
have a reasonably cheap, large capacity storage technology), or we 
cycle other plant to take the load. Since we've already used just 
about all the <politically> possible pumped-hydro storage sites, that 
means we have to cycle conventional plant more if we have large 
amounts of solar.


Now we're even more off topic !

-- 
Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
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