Nerdy news of the day: Solar energy higher efficiency at parity with fossil fuels?

by darthfader 18 Replies latest social current

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  darthfader

  http://www.ispyce.com/2011/03/solar-energy-telescopeare-are-efficient.html

  A University of Arizona engineering team led by Roger Angel has designed a new type of solar concentrator that uses half the area of solar (PV) cells used by other optical devices and delivers a light output/concentration that is over 1000 times more concentrated before it even hits the cells. This comes as a result of a broader goal to make solar energy cost competitive with fossil fuels (target = 1$/W) without the “need for government subsidization.”
  
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  JeffT

  Interesting, but they still run up against an upper limit: the amount of solar energy available at the earth's surface. Very large scale generation is going to cover a big area with something.
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  Satanus

  As well, there's the hurdle of the dissappearing sun problem.

  S
• 

  villabolo

  JeffT:

  "Interesting, but they still run up against an upper limit: the amount of solar energy available at the earth's surface. Very large scale generation is going to cover a big area with something."

  Yes, solar energy is very diffuse, but that is not really an "upper limit". Only a fraction of the state of Nevada would be needed to provide enrgy for this nation in abundance.

  Villabolo
• 

  beksbks

  Again Germany is way ahead. And they are not a particularly sunny country. I have to assume it's because they have little oil industry working against the sustainable energy market.
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  freeman

  I’ve been a big solar energy fan since I was a kid. I remember having a working solar thermo powered motor, photo voltaic cells wired all over the place and it was neat stuff to play with, but I found out when I wanted to power my bike that it was also not practical in the real world, a lesson that stuck with me. That was years ago when I was a kid, but even now many years latter I find most of the green energy h oopla is still more pipedream then reality.

  Jeff is correct, no matter what the efficiency may be in the future; the raw photon energy concentrations per meter of space make sunlight derived power expensive and very limited. As a supplemental form of energy and for use in areas not well served by outside utilities, excellent I say go for it! But as for being any type of viable contender for fossil fuel, no chance whatsoever. It’s a simple matter of physics combined with economics.

  IMHO a better idea would be to employ a smart use of old-school green technology combined with cheap and abundant fossil fuels. I suggest the use of proven fuel cell technology which has now advanced to the point of being able to burn not just pure hydrogen as before, but now can convert impure hydrocarbon fuels like natural gas and bio-gas directly into electricity.

  Such devices are right now on the job producing electricity at less then the cost of commercial power utilities and with reduced emissions. A unit the size of an average parking space will power about 100 average size homes or one small office building. Such units have been on the job powering the likes of Google, Bank of America, Walmart etc. They report they are saving money.

  Considering we have an abundance of natural gas reserves and the price of natural gas is well below that of other fules and trending lower, we could easily cut our dependence on imported fuels quite a bit and reduce our emissions all at the same time. And unlike many green alternatives, this is not a pipe dream, not a promise of some future breakthrough that never seems to come, but a practical working solution with real-world working examples right now.

  And should the other green solutions one day become practical in the real world, great! We can always switch over to the new green technology as they become available.

  Check out this fuel cell startup company as an example (Bloom Energy). http://www.bloomenergy.com/

  Freeman
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  darthfader

  Any system that consumes natural gas, coal or other fossil fuels will eventually consume the fixed amount we have on earth. Even converting natural gas into electricity using Bloom Energy's fuel cell produces CO2 (yes it's really limited, but it adds to the total CO2 in the atmosphere).

  I'm not a big advocate of photovoltaic cells. Their efficiency is still too low (about 15%) to be really cost effective. Instead, I think Solar Dish Stirling ( http://en.wikipedia.org/wiki/Stirling_engine ) is a more approachable solutions. Basically it's a heat differential engine - keep one side hot (focused sunlight) and the other side cool (in the shade with radiator fans) and you get movement which can turn a generator for electricity. These run at about 35% to 40% efficiency.

  If you need energy for running vehicles (not our current gas guzzlers, but proton exchange membrane fuel cells) then you can generate hydrogen using high temperature electrolysis ( http://en.wikipedia.org/wiki/High-temperature_electrolysis ) to crack water into O2 and H. Using concentrated solar power (again mirrored dishes or troughs) and a lot less electricity, you can get a conversion ratio of about 40% to 64%. This hydrogen can be bottled and placed into cars.
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  darthfader

  If you really want to make the hydrogen into something useable by current cars (think natural gas conversions) there is a process for converting hydrogen and Co2 into Methane ( http://en.wikipedia.org/wiki/Sabatier_process ). I think it’s still experimental, but the chemistry is pretty straight forward.
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  Mad Sweeney

  Here's an idea I had. If you're an engineer, feel free to run with it. Just donate to freeminds.org when you strike it rich and mention Mad Sweeney.

  Develop some sort of carpet or groundcover that generates electricity when people walk on it. Every step actuates the mini-generator units beneath it. Place it in high-traffic areas, hallways, walkways, sidewalks, etc. Each square meter would need to have hundreds or even thousands of mini-generators in it, but when all put together, they could charge batteries that would power the lights overnight.
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  freeman

  I like the idea of a Stirling engine. I believe this is the very same device I experimented with when I was a kid but I didn’t remember it by that name. It works on temperature differentials, so solar powering it is one option, really anything that produced sufficient heat would work.

  You are of course correct Dart, natural gas or any other hydrocarbon does produce undesirable emissions and there is a finite supply of it. But the supply we have here in the US is tremendous, more then most nations I believe. It can’t be the final solution for sure, but I could see it as a possible bridge until the technology breakthrough we all long for comes about. If nothing else, it could help us to move away from dirty coal and oil fired power plants right now without the sticker shock. Just a thought.

  Freeman