| Archive for alternative-energy.co.uk Discuss experiences and share information about installing renewable or alternative energy in your house. |
| gerrywolff |
Concentrating solar powerEnormous quantities of energy fall as sunlight on the world’s hot deserts and ‘concentrating solar power’ (CSP) is a proven technology for tapping in to it (see, for example, the website of the US Government's Department of Energy at www.eere.energy.gov/solar/csp.html). This is not some futuristic possibility like fusion nuclear power. CSP IS A RELATIVELY SIMPLE, MATURE AND PRACTICAL TECHNOLOGY THAT, WITH THE RIGHT POLITICAL AND FINANCIAL IMPETUS, CAN BE BROUGHT INTO PLAY VERY SOON.'Power towers', for example, use a large field of sun-tracking mirrors to concentrate sunlight on to a receiver on the top of a low tower. The sun heats a fluid inside the receiver. An early U.S. demonstration plant, Solar One, used water as the fluid, generating steam in the tower to drive a turbine to generate electricity. 'Trough systems' use parabolic trough-shaped mirrors, each one of which focuses light on a tube containing oil or similar fluid that takes the heat to where it can be used to raise steam and generate electricity. And each 'dish/engine' system uses a large sun-tracking mirror with a Stirling engine generator at it focal point to convert heat energy into electricity. The heat from concentrating solar power plants can be stored in melted salt or other substance so that, when the sun goes down, the power plant can continue to generate electricity right through the night. People in the UK and elsewhere in Europe apparently assume that CSP is not relevant to their needs because they are a long way from the kinds of hot deserts where CSP comes into its own. But average transmission losses over modern high-voltage DC transmission lines (HVDC) are about 3% per 1000 km. In round figures, this means that electricity can be transmitted from North Africa to London with only a 6% loss of power. Since the 'fuel' for CSP is free, any such loss is quite acceptable. The Trans-Mediterranean Renewable Energy Cooperation (TREC) argue that CSP plants—and wind farms—in North Africa and the Middle East can provide electrical power for those areas and for the whole of Europe with transmission losses that would be less than 15%. That level of loss compares extremely favourably with the 70% losses that have been accepted for many years from conventional coal-fired power stations where the fuel is far from being free. An alternative to high-tension power lines is to use solar electricity to generate hydrogen by the electrolysis of water and then transport the hydrogen by tanker or pipeline to where it is needed. There is a nice fit between wind power in northern Europe, which is greatest in the winter, and solar or wind power from North Africa and the Middle East, which is greatest in the summer. Some detailed projections prepared for the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) by 'TRANS-CSP' show how, even allowing for increases in demand for energy, a combination of CSP with other technologies could allow Europe to cut CO2 emissions from electricity generation by about 70% by the year 2050, and phase out nuclear power at the same time. CSP BONUSES: CSP can yield much more than inexhaustible, pollution-free electricity: * Shading for buildings, car parks, other public spaces or stables for animals to help keep them cool. * Waste heat used for desalination of sea water or for air conditioning. * Horticulture out of the harshness of direct tropical sunlight. * Jobs and earnings throughout Europe, the Middle East and North Africa. Further information, with links to other sources, may be found at http://www.mng.org.uk/green_house/renewable_energy/csp.htm . |
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| admin |
Hi Gerry,
Reminds me of the quote from Jeremy Leggett in 'Half Gone' that solar panels with an area of 600km2 situarted in the Saraha could produce all the world's energy. Of course there's the issue of transporting the energy but the principle is obvious. |
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| gerrywolff |
From what I have learned, Jeremy Leggett is spot on. Given this huge resource and and a nice simple technology for exploiting it, it is amazing that it is apparently invisible in UK Government thinking and in the writings of many commentators. As far as I can see, it is being overlooked because people simply cannot believe that solar power can be transported from the Middle East and North Africa to the UK and other parts of Europe. But it is entirely feasible and affordable to do this with HVDC transmission lines or using Hydrogen as an energy vector. The necessary technologies already exist. |
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| Guest |
G'Day guys,
gotta say that I am not a big fan of large centralised energy infrastructure of any sort - you still have to buy it from a large sorp with all of the disadvantages and loss of control that go along with it. Small personal or perhaps street based "micro" generation is the way to go. No huge structures, less line losses and independance for the system. That's my two bobs worth anyway! Nev |
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| Wombat |
Sorry, that was me! I thought I was logged in when I wasn't!
Nev |
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| gerrywolff |
Going fully-decentralised implies dismantling the grid. No grid means no energy from offshore wind farms, wave farms, marine current turbines or tidal lagoons. It doesn't make sense! The grid may be ugly but it is needed if we are going to gain the advantage of the kinds of renewable energy that I mentioned. Microgeneration is important but it is by no means the whole answer. |
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