Thursday, May 26, 2005

solar energy uber alles

Most of our energy is derived indirectly from the sun, which is a nuclear energy producer, (to say the least).

So, Peak Oil Optimist, posts on a good idea vis a vis solar energy:
The Endless Energy Well in the Deep Sea
Via Wired, a pretty interesting story about one Dr. John PiƱa Craven, the "brilliant psychotic" behind the Navy's Polaris program, and now with an equally half-crank, half-why-didn't-I-think-of-that solution to the world's energy problems: placing pipes to the ocean deeps to harvest the temperature differential between the upper (warm) layers of the oceans and the lower (near freezing) depths.

If we must invest billions in a new infrastructure, this kind of idea I can get wholeheartedly behind; it doesn't pollute. Viability - who knows, got to get cracking, "civilization" is way behind the eight ball when it comes to investing in sources of energy that don't fang back.

Update:
I got smacked down in the comments for this one, which will teach me to link to the techno fabulists at Wired. This technology has about as much promise as fusion - it is fifteen to twenty years out, now and yesterday.

Engineer-Poet said:
Examine the technology. For all the recent hype about OTEC, the technology seems to have advanced but little since its last turn in the news spotlight. All the available energy in the universe counts for zilch if we can't capture and convert it affordably.

6 Comments:

At 5:29 AM, May 27, 2005, Anonymous Anonymous said...

If we must invest billions in a new infrastructure, this kind of idea I can get wholeheartedly behind; it doesn't pollute.

Go look into the idea of what happens when the ocean water stops moving from the equator to the poles.

In addition, go research the 'frozen' methane at the bottom of the ocean.

Then, think about the exactly how good an idea this 'cold water/hot water' pipe is.

 
At 9:10 AM, May 27, 2005, Blogger monkeygrinder said...

Those are some good points.

Save the lectures, all I need is information.

Obviously, no one wants to warm up the methane, (except the USGS), so you wouldn't want to put one of these over a methane hydrate deposit.

 
At 10:01 PM, May 27, 2005, Blogger Engineer-Poet said...

Before going further with this idea, do the following:

1.  Examine the foundations.  Look to see how much cold water is generated in the environment, and how much humans can use without disturbing the equilibrium of the oceanic thermoclines.  (Warming continental shelves by pushing the thermocline down would destabilize methane hydrates.)
2.  Examine the technology.  For all the recent hype about OTEC, the technology seems to have advanced but little since its last turn in the news spotlight.  All the available energy in the universe counts for zilch if we can't capture and convert it affordably.

 
At 3:37 PM, May 28, 2005, Blogger Engineer-Poet said...

I just went through one of the OTEC papers (can't recall where I got the link) and it mentioned 3500 m^3/day of fresh water per megawatt of capacity.  The heat of vaporization of water at 5°C is 2489.6 kJ/kg, so condensing that much vapor would produce about 101 megawatts of heat.

In other words, OTEC is around 1% efficient.

 
At 10:53 AM, June 05, 2005, Anonymous Robert said...

That's right, the efficiency of the OTEC scheme is somewhere between 1 and 2%. This efficiency should be compared with the efficiency of the photosynthetic process going on in plants which is in my estimate more than 1%. In comparison, solar panels achieve almost a tenfold efficiency (around 15%). Wind turbines, depending on size achieve efficiency rates of over 50%. The problem of solar and wind energy is that they are not avaiable 24 hours a day. They require a storage device which will further decrease efficiency. Please note that plants convert solar energy into sugars and store at the same time that energy in biomass. It could well be that the overall efficiency of plants is very close to the technological optimum which can be achieved in harvesting of solar energy on a large scale. (How could it be otherwise given the fact that plants evolved over billions of years while our technology is at best 100 years old?) If that is true, than we should reforest every piece of land which is not used for agriculture.

In my opinion, the future of human civilization will be in solar and wind together with dramatically improved levels of efficiency. However, there is no way that we will be able to continue consuming the huge amounts of energy per head of population as we do today. That is simply not sustainable regardless the type of technology we might invent. It is a scandal that almost every house build today still requires a heating system. We know how to build superinsulated houses in such a way that no heating is required. The present energy crisis is actually a crisis caused by our collective stupidity in designing and constructing the infrastructure of our cities and transportation networks. In order to save a buck we risk the future of the planet.

 
At 10:20 PM, June 06, 2005, Blogger monkeygrinder said...

Robert, some good points. Thank you.

I believe we can make hay with conservation. People wont be turning up the heat in the future, they'll be putting on a parka.

Hopefully, this will get us through the first pulse of depletion.

 

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