the Air Vent

Because the world needs another opinion

Green Energy

Posted by Jeff Id on July 20, 2009

Calling me a skeptic on biofuels is an understatement, I’m a denier.   If you’ve invested in biofuels, my opinion is that you need to do it with the understanding that the technology doesn’t really work.  There simply isn’t enough capture of sunlight to make the process operate to the claimed levels.

Super Algae Bio-Diesel Energy

I feel similarly about solar although in the case of solar, there is a reasonably good chance that in the future it can generate much of our needs.  Geothermal is interesting though.  I’ve not studied the costs which are said to be low but in today’s  geothermal plants, temperatures are required to be quite high in order to turn water into steam. In some plants two wells are drilled (typically very deep wells), the rock between them is shattered using explosives or other methods, water is sent down one pipe and steam returns up the other which then powers a series of turbines.

img037

One of the big drawbacks of geothermal is that in many locations on earth the magma doesn’t come close enough to the surface to provide enough temperature at an achievable drilling depth.   The result is warm rock too cool to make steam but there is still a great deal of energy available.  The ability to use this lower heat efficiently could dramatically expand the use of geothermal energy by making it practical in  more areas.  From an engineering perspective, the answer to solve the problem is to use a different fluid which changes phase at a lower temperature, however finding a different fluid is a challenge.

Today on Science Daily, there  was an interesting article which used a phase changing fluid created from new materials.  They claim the efficiency of their method is similar to a steam based one using different materials at lower temperatures.

ScienceDaily (July 20, 2009) — A new method for capturing significantly more heat from low-temperature geothermal resources holds promise for generating virtually pollution-free electrical energy. Scientists at the Department of Energy’s Pacific Northwest National Laboratory will determine if their innovative approach can safely and economically extract and convert heat from vast untapped geothermal resources.

This is a description of how they did it.

To aid in efficiency, scientists have added nanostructured metal-organic heat carriers, or MOHCs, which boost the power generation capacity to near that of a conventional steam cycle. McGrail cited PNNL’s nanotechnology and molecular engineering expertise as an important factor in the development, noting that the advancement was an outgrowth of research already underway at the lab.

I’m sure that even if it works there are other problems to be considered, like the introduction of an odd chemical to the rock.  If the costs are as low as other geothermal energy, this could be a very serious improvement.

My opinion on where we should be heading with energy is that we should expand capacity and usage of CO2 producing energy to keep costs as low as possible on our economy while staying away from government funded energies who’s technology isn’t ready to be introduced.  The technology to actually stop using CO2 based energy production will be available in 50 years and already is in nuclear.  It is only our artificial limits created by politicians, and leftist organizations which will limit the introduction of these potentially newer cleaner and — cheaper, technologies.  False ideologies and a lack of economic success can do nothing but delay their introduction.

Whether you agree with me or not, one thing I am sure of is that nobody knows how much warming will occur from doubling CO2.   People in climatology who claim certainty are foolishly wrong or even occasionally dishonest in my opinion and it is a highly visible problem in climate modeling.  Models often disagree and are only as good as the knowledge put into  them.  Waiting 30 years and expanding our current usage would give the time needed to clear up the substantial and undetermined details in climate modeling and perhaps people looking to make money will find a better way in that time.  Don’t forget, it was only 110 years ago when we stopped riding horses.

Anyway, maybe these guys really have something.

The Science Daily article is at the link below.

New Geothermal Heat Extraction Process To Deliver Clean Power Generation

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img037.jpg Geothermal image by Demicus

15 Responses to “Green Energy”

  1. Jeff, I browsed the sources a little bit. All they seem to have done is got funding to look at a concept. It doesn’t look like they’ve accomplished anything.

    Another practical type of geothermal (in use today) is in heat pumps. You can put tubes into the earth/lakes to exchange heat for use in heat pumps. These can be used for both heating and air conditioning using conventional technology.

  2. peter vd berg said

    I’ve understood that geothermal’s biggest problem is you can only extract heat enough to really power a generator if you pump in massive quantities of water. You need to have the right geothermic hot-spot and a plentiful source of water to run it. It’s hard to find the 2 in the same place.

    As there’s quite bit of steam to be cooled down enough to turn it into fluid-state there’s quite a loss of water to the air.

    So once your water source runs dry, it’s done.

    The only real application would be in a closed heat exchange system, but that would only serve for heating purposes.

  3. curious said

    2- Peter – the story is they have a new working fluid other than water and they claim the process will run a turbine.

  4. Ryan O said

    Geothermal’s good for residential use. Lots of Michigan homes use geothermal. Unless you need to replace your furnace/central air system, adding it to an existing home doesn’t have a great payback, but if you start out with geothermal, the payback on the incremental expenditure (over and above what you’d have spent on a gas/propane furnace) is typically ~5-7 years.

    I like geothermal. Much cool. As with all this stuff, the promises are usually MUCH greater than what can actually be delivered, but this one seems feasible, at least.

  5. Page48 said

    Jeff – somewhat OT but related; I wish you would bring up a post on Carbon Sequestration, a really bad idea. I would like to hear what your readers think about this. The idea is bandied around a lot in the government and might actually get some play.

  6. Jeff Id said

    #5, It’s not a bad idea. I’ll do some reading.

  7. Rebar said

    Jeff,

    I’m only a sometimes reader – I usually come over from WUWT – but I’m suprised to read that you believe solar power has the potential to provide a significant amount of power. At only about 1350 w/m2 at the top of the atmosphere, and then losses for atmosphere, weather, NIGHT, and whatever conversion medium used, it doesn’t seem like its very pratical at all. Even getting rid of all the losses, 1350 w/m2, doesn’t seem like an efficient use of space, when compared to fission, or in the future, fusion.

  8. Jeff Id said

    If solar get’s to 20 or 30% as some research cells have done and the cost is under $1/watt in today dollars, I would put a system on my house. My preference is improved nuclear power but it turns out that nobody asks me :)

  9. DeWitt Payne said

    Since this is a heat engine, aren’t you always limited by Carnot cycle efficiency? If the rocks aren’t hot enough to generate steam pressure on the order of 1200 psi or so, the thermal efficiency is going to suck. You’re going to generate a lot of heat pollution and not much electricity even if you recycle 100% of your operating fluid.

    My son-in-law’s grandfather had a house on a river and used river water in his heat pump heat exchanger. He even rigged it to heat his swimming pool. Very efficient when it worked and wasn’t leaking all over the basement.

    As far as carbon sequestration with algae, the numbers I’ve seen are that you might be able to remove about 40% of the CO2 from a typical fossil fuel power plant if you have 14 square miles of pond area.

  10. Jeff Id said

    The Carnot cycle efficiencies cannot be violated. Don’t mix up efficiency with function. The point is using a different material than water, it may be possible to drive these temp sources at a good return.

    It may take the time to work the numbers but a 14 mi^2 pond would be one of the biggest lakes I’ve seen and I grew up in Michigan – yes it’s dwarfed by the great lakes but there are 10,000ish other lakes inland which are smaller than 14 sq miles. Not that it’s necessarily impractical to use a huge lake.

    My guess is that 14 sq miles for algae is impractically too small. Photosynthesis can’t keep up. no numbers from me tonight but perhaps tomorrow.

  11. AEGeneral said

    #4

    My brother is building a new house & we’ve been exchanging e-mails about this as well as solar panels (which I think I talked him out of with an estimated ROI of 18-20 years by my calculation). He talked to a local contractor in Memphis, and to my surprise, 30% of his business is now geothermal. I didn’t know it was feasible in this area of the country.

    He figured an ROI in the neighborhood of what you’ve stated, which included federal tax incentives of some kind.

    I only questioned the maintenance costs. Still haven’t heard back from him on that part.

    Only negative I’ve ever read about with geothermal was a town in Germany that is sinking because they didn’t do it correctly (yikes).

    This is the only “alternative” energy that has any real potential in the short-term, IMO. But I’m still not comfortable with these alternatives being subsidized 5 to 1 over oil, natural gas & coal, and yet they only contribute 2.4% to the electrical grid. I suppose if cap & trade becomes a reality, though, getting partially off the grid would at least provide a degree of personal energy independence.

  12. If you’re relying on tax breaks to make something economical, you’re on dodgy ground!
    Anyone living in Yosemite should be able to use geothermal, but I’d bet that you’d never get permission to drill, incase it upsets Old Faihful’s output.

  13. curious said

    AEGeneral – Passive design and good insulation are IMO the best starting point for a new build. Look at some of the performance that the PassivHaus approach achieves:

    http://www.passivhaus.org.uk/

    http://www.passiv.de/

  14. curious said

    Jeff – From memory I think there were schemes using lakes as district heat stores in Scandanavia but I don’t have a ref. Quick first Google gives this Wiki entry with US/Canadian examples:

    http://en.wikipedia.org/wiki/Deep_lake_water_cooling

  15. curious said

    Rebar – you need to average your solar input over the course of a year and have data relevant to your location. I think typical US figures are 300-500W/m2. As a decentralised energy source well worth having but for PV cost is high – thermal is generally better cost/benefit. Lots depends on what you need it for and how efficient you are with use. Suggest Rocky Mountain Institute as a good US start point on this:

    http://www.rmi.org/sitepages/pid23.php

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