Solar-thermal power touted as energy solution

Discussion in 'Designing, building, making and powering your life' started by bazman, Mar 31, 2006.

  1. bazman

    bazman Junior Member

    Joined:
    Jul 4, 2005
    Messages:
    802
    Likes Received:
    2
    Trophy Points:
    0
    Now this sounds like a bloody good idea. I wonder how Australias coal industry will react.

    https://www.abc.net.au/news/newsitems/200603/s1605734.htm

    Australian scientists have developed a new form of electricity that could provide all of Australia's electricity needs in 2020.

    It has been developed by mixing solar energy, heat and natural gas.

    In the search to find a cleaner, more efficient form of power, scientists at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) have developed what is called solar-thermal energy.

    Two hundred mirrors track the sun, and focus the sun's rays towards a tower.

    The heat can reach temperatures of more than 1000 degrees Celsius, producing 500 kilowatts of power.

    This is then mixed with natural gas and water to produce a renewable energy.

    Wes Stein from the CSIRO says the new development could provide for Australia's future energy needs.

    "It would only require about 50 kilometres by 50 kilometres in the centre of Australia somewhere to provide all of Australia's electricity needs in 2020," he said.

    "That's not very much of Australia."
     
  2. ho-hum

    ho-hum New Member

    Joined:
    Sep 15, 2005
    Messages:
    1,590
    Likes Received:
    0
    Trophy Points:
    0
    Baz,

    As far as I know a project like this is under way near Mildura, Vic and has been for a number of years. I do believe the land was purchased about 5 years ago.

    I am not sure of the technologies used in Mildura. Here is a valid link https://www.solarmissiontechnologies.com/index.html

    This one uses super salt water as receptors, not sure how they move the heat up the chimney.

    All good stuff we really have to decide as a nation that coal-fired power generation has to stop sometime and put a timeline on it.
     
  3. Ian Gordon

    Ian Gordon Junior Member

    Joined:
    Apr 2, 2006
    Messages:
    4
    Likes Received:
    0
    Trophy Points:
    0
    The solar power tower has been in the process of being built for years. It has raised money from stock options on a number of occasions. It's decidedly depressing that a good idea that has been tested and shown to work in Europe, Manzanares in Spain to be exact, should not produce any worthwhile results in Australia. This is big solar power rather than the infinitely preferable small solar power that puts energy firmly in the hands of the general public as well as encouraging a sense of civic responsibility.
     
  4. heuristics

    heuristics Junior Member

    Joined:
    Oct 19, 2005
    Messages:
    519
    Likes Received:
    0
    Trophy Points:
    0
    solar energy

    Of course there is always the nuclear option – good to see that the ALP policy of “no new uranimum mines” of decades standing has now been declared “out dated by unionist Martin Ferguson (seen on Ch 9 Sun am). More uranium mines, more jobs, and that's gotta be good for the lucky country!.....
    (why do I watch these things... it makes me so sick.....)
     
  5. scooter1962

    scooter1962 Junior Member

    Joined:
    Jul 11, 2005
    Messages:
    16
    Likes Received:
    0
    Trophy Points:
    0
    the mob building the thermal tower are called Enviromission, and I understand they have several projects like this in other parts of the world. The tower to create the termal pull was set to be 1 km high, but they've improved the technology and can now make it smaller. The flare at the bottom of the tower is 5 km across, it collects the heat and this is funnelled across turbines set at the base of the tower.
     
  6. bazman

    bazman Junior Member

    Joined:
    Jul 4, 2005
    Messages:
    802
    Likes Received:
    2
    Trophy Points:
    0
  7. SueinWA

    SueinWA Junior Member

    Joined:
    Feb 25, 2005
    Messages:
    1,251
    Likes Received:
    1
    Trophy Points:
    0
    I don't understand.... how is natural gas renewable? Isn't it somehow associated with oil (petroleum) drilling? Or have I got this all wrong? (Could be... I don't understand electricity at all -- it's the same as magic to me.)

    If you understand it, please explain in small words and short sentences for the scientifically-challenged!

    Sue
     
  8. Jim Bob

    Jim Bob Junior Member

    Joined:
    Feb 18, 2006
    Messages:
    258
    Likes Received:
    1
    Trophy Points:
    0
    Sue, your instincts are correct.

    Tradtionally, we burn fossil fuels to create heat, and this heat expands a gas, moving a piston. The piston turns a wheel. The wheel can then move a car, or it can move past magnets, generating electricity, as in power stations. Nuclear power by the way uses the same principle - nuclear reactor heats liquid, liquid moves and moves piston/wheel, etc.

    There are two problems with burning things to get energy. The first is that we'll eventually run out of things to burn. Even if the whole planet were made of oil, still we'd eventually run out. The second is that what we burn produces things which are bad for us, and which affect the world in other ways, like acid rain and the greenhouse effect.

    The basic reaction is C (carbon) + O2 (oxygen in the air) => CO2 + energy. When the carbon joins to the oxygen, it lets go energy - like when you burn a candle, the flame is hot.

    Now, we can burn lots of things. The carbon doesn't usually sit around by itself, it's in the form of hydrocarbons, the "hydro" meaning "hydrogen." So for example methane - "natural gas" - is CH4, a carbon atom with four hydrogen atoms attached to it. When we burn it, we get the reaction, CH4 + O2 => CO2 + H2O (water) + energy

    But we can have more complex hydrocarbons. The carbons atoms join into little chains, with hydrogen atoms hanging off them. These chains are like long strings, they get tangled with each-other. That's why methane - CH4 - is a gas, while decane - CH3-(CH2)8 - CH3 is a liquid. In crude oil, we boil the stuff in big columns, and the lighter fractions burn off first. So we separate out the lighter stuff for plane fuel, then the next heavier for car fuel, and so on and so forth all the way to bitumen, which we put on our roads.

    And then of course there's coal, which is a lot of the longer and more complex hydrocarbons mixed together with chunks of pure carbon. Because that stuff's not one pure kind of molecule, when it burns, you get all kinds of crap in the air, and get acid rain and so on. The sulphur makes sulphuric acid, etc. Same goes for burning wood.

    Okay, so much for making energy by burning carbon. Are there other things we can burn to make energy? Well, yes. We can burn hydrogen.

    H2 + O2 => H2O + energy (more energy than burning C)

    Looks great, eh? The only waste is water! So if we change to burning hydrogen, then no worries!

    Well, there are a couple of problems. The first is an engineering problem. H2 in gas form takes up a LOT of space. You'd need a fuel tank the size of a bus. We can make it a liquid, but that's like -260C where it becomes liquid, so then we need expensive refrigeration equipment. At least our modern cars don't use power when they're not running. But a car powered by liquid hydrogen would use power all the time, just to keep the fuel liquid!

    Still, that's an engineering problem, and people are working on solutions to it. So let's imagine that's solved. We still have another problem. Where do we get H2 from? Carbon, in oil and coal and gas and wood, that's everywhere, just pick it up, easy. But H2? Well... it doesn't sit around by itself. It reacts so easily that hydrogen is sitting around locked up in molecules. Okay, what do we have a lot of in the world? Water! H2O. Hey, that has a hydrogen atom in it, doesn't it? So,

    energy + H2O => H2 + O2

    Notice that's the reverse of the reaction above. If mixing hydrogen and oxygen to make water gives us energy, then splitting water into hydrogen and oxygen will take energy.

    So, where do we get this energy from? Because remember, one of our reasons for wanting to burn H2 is because the C will run out, yeah? If the C's run out, how do we get the energy to burn H2? We can't burn H2 to split water to get more H2, we'll always end up with less H2, that's a law of physics. You don't spin a wheel and it ends up going faster by itself.

    Okay, so we need some way to get electricity to split H2O into hydrogen and oxygen. Hmmmm...

    So the CSIRO guys have said, hey, even without electricity, there's another reaction. You don't have to go, energy + H2O => H2 + O2, in fact you can go,

    CH4 + H2O + energy => CO2 + H2

    So what they've done is set up big mirrors to concentrate heat on a tower. This heat raises the temperature of the methane and the water. See, methane is a gas, and water's a liquid, so they don't normally mix enough to react to form carbon dioxide and hydrogen. But if we make them both really hot gases - say, by heating them with the sun in a tower - then they'll react, and we'll get hydrogen!

    Of course, we'll also get CO2. And we'll use natural gas, a fossil fuel.

    Now, since the WHOLE POINT of burning hydrogen was because we're going to RUN OUT of fossil fuels, and so we DON'T produce more CO2... this is the most stupid idea the CSIRO has ever had. By far. It's entirely pointless. It's exactly equivalent to simply buring the methane, it produces exactly as much CO2. Only it requires us to build these solar towers and develop new kinds of car engines, etc etc.

    It's a longer way around to the same destination: Destination No More Fossil Fuels, and Hot World.

    Notice that on their page describing the project, they note the CO2 created and say "to be disposed of by geosequestration or other technology." "Geosequestration" is fancy-talk for "um, we'll bury it, I guess."

    The whole thing is a stupid idea. If we're to burn hydrogen, then this isn't the way to generate the hydrogen. Better would be solar and wind-generated energy splitting the water by electricity, "electrolysis" (different process to what the beautician does to your legs...)
     
  9. bazman

    bazman Junior Member

    Joined:
    Jul 4, 2005
    Messages:
    802
    Likes Received:
    2
    Trophy Points:
    0
    Another interesting energy story.

    Supporters of an alternative energy source say it has the potential to revolutionise the nuclear power industry and is a safer alternative to uranium.

    Thorium oxide, which is three times more abundant than uranium, is also a radioactive material.

    https://www.abc.net.au/news/newsitems/200604/s1616391.htm
     
  10. Jim Bob

    Jim Bob Junior Member

    Joined:
    Feb 18, 2006
    Messages:
    258
    Likes Received:
    1
    Trophy Points:
    0
    The thorium reactor designs are several, and all unproven. They will produce radioactive material, deadly for hundreds of years instead of hundreds of thousands of years. I think "deadly for hundreds of years" is deadly enough that we don't want to use them;)

    Also, though thorium is about three times more present in nature than is uranium, still it's finite - it'll run out.

    So for renewable energy, we have the choice between

    a) technology that doesn't work yet and that uses a fuel that will run out (thorium reactor), or

    b) technology that has worked for fifty years and uses a fuel that won't run out in the next 1 billion years (solar and wind)

    I think it's best to focus our efforts on the second one... Of course we should study all kinds of ways to generate energy, but I won't be refusing to put solar panels on my roof because I'm waiting for them to build a thorium reactor.
     

Share This Page

-->