Saturday, September 09, 2006

Energy Payback Time for PV and Wind

Energy Payback Time for PV and Wind (life cycle analysis / embodied energy)

I`m pissed. The ammount of junk information that gets thrown my way is realy starting to get on my nerves. I mean, it's going to happen from the typical sources, from the insane neo-libs, the pro-fossil fuel lobby etc. But when it comes from fellow environmentalists and people with a stated interest in energy it just plain pisses me off!

As i have my own views on things--I have my own world view--and as I realise that world views are personal things, I don't like to dismiss claims without direct reference to evidence. The reason I get pissed with people throwing junk info my way when they should know better is because I have to do the leg work that they should have done.

And breathe...

When i was at the climate camp recently I went to a fairly impractical workshop on practical off-grid living. It was interesting up to a point, it became instantly less interesting when the guy giving the workshop started talking bollocks...and not clarifying what he was talking bollocks about!

He stated that solar PV was basically energy neutral (co2 pay off roughly within its life time).

First off, this is wrong. Secondly even if it was right he should be inspiring not making us feel hopeless...he could have empahsised other technologies. Thirdly he didn't clarify that he was talking about monocrystaline solar PV rather than amorphous or solar warter heating.

And relax...

When checking these facts I always look for an academic source/govornment advisory group not a business report/thinktank.

Here are some reports on the topic:
1. Report by Tyndall Centre for Global Climate Change (UK Research Centre)
2. Report by ECI (Oxford University, UK)
3. Report by House of Lords Science and Technology Committe (Cross Party Advisory Board)

"The semiconductor materials currently in volume production are monocrystalline silicon (crystalline), poly-crystalline silicon (crystalline), amorphous silicon (thin film), and cadmium telluride (thin film). Systems are expected to have a lifetime of at least 25 years, with low maintenance requirements.

...Depending on technology and solar radiation, the energy pay-back period
canbe between 2.5 and 4 years."

Bellow is a table with wind power payback times in terms of carbon, and bear in mind this is from 4 years ago, before the dramatic scale up and therefore lowering of carbon intensiy per unit energy of generation capacity.

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At 7:51 PM, Anonymous Anonymous said...

Absolutely right -- photovoltiac cells easily pay for themselves and "reproduce" energetically many times over their lifetime -- even crystalline silicon does well -- see this article by J. Pearce and A. Lau "Net Energy Analysis For Sustainable Energy Production From Silicon Based Solar Cells" Proceedings of American Society of Mechanical Engineers Solar 2002: Sunrise on the Reliable Energy Economy, editor R. Cambell-Howe, 2002.


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