Sunday, June 27, 2010

Desertec - Energy From the Sahara to Europe.

The European Energy commissioner has announced that the project Desertec will begin to provide electricity to Europe within 5 years, which is half the original estimate.The project is partly funded by the European Union and companies within Europe, to aid the EU in meeting its target of generating 20 percent of its energy from renewable sources by 2020. The Desertec scheme has been described as being part of an overall intention to create "a new carbon-free network linking Europe, the Middle East and North Africa".

Desertec is a project officially launched on the 13th of July 2009 by twelve European companies. It operates under the auspices of the Club of Rome and the Trans-Mediterranean Renewable Energy Cooperation. The project intends to install a network of concentrating solar power systems over an area of 6,500 square miles (17,000 km2) in the Sahara Desert, to produce electricity that would be transmitted to European and African countries by a super grid of high-voltage direct current cables. At a total cost of €400 billion, the scheme would provide continental Europe with 15% of its electricity, although the precise course of action and final costings will be presented in 2012.

The location is logical, since the Saharan desert is virtually uninhabited and is close to Europe, and being close to the equator is well provided for by sunlight. It is voiced by its protagonists that the project will keep Europe "at the forefront of the fight against climate change and help North African and European economies to grow within greenhouse gas emission limits"; however this are notes of criticism too. As usual, some opponents to the scheme point out that centralized solar energy plants and transmission lines could become a target of terrorist attacks, while others are of the opinion that generating so much of electricity consumed in Europe in Africa would create a geopolitical dependency on North African countries.

There are further issues over the demand that will be imposed on local freshwater supplies, in terms of cleaning and cooling turbines, which may impact on drinking water supplies for local villagers. Undoubtedly, unprecedented cooperation will be required between nations of the EU and Northern Africa which may delay the project through red tape, especially over the expropriation of assets, the granting of licenses and so forth. There are environmental issues too, in that the Earth’s deserts act to cool the planet by reflecting heat energy, and if they are instead covered with heat-absorbing installations there may be a contribution to global warming.

Related Reading.
(2) C.J.Rhodes, "Solar Energy: Principles and Possibilities," Science Progress, 2010, Vol. 93, 37-112.

Saturday, June 26, 2010

Concentrating Solar Power Generation.

Concentrating Solar Power (CSP) systems employ lenses or mirrors coupled with tracking systems to concentrate a large area of sunlight into a small beam, rather in analogy with the simple and familiar burning-lense. The concentrated energy may be used to heat a central “boiler” to run a power plant fitted with a conventional steam-turbine from which electricity is generated in the usual manner. A quite broad range of methods may be used to accomplish this, e.g. the parabolic trough, the solar (parabolic) dish and the solar power tower.

All such systems contain a working fluid which is heated by the concentrated sunlight, and then used to generate power or to store energy. In a parabolic trough there is a linear parabolic reflector which concentrates sunlight onto a receiver oriented along its focal line. By means of a tracking system, the reflector follows the Sun during the daylight hours along a single axis. Trough systems are the most efficient of any solar technology in regard to the land area occupied by the plant. The SEGS plants in California and the Acciona Nevada Solar One near Boulder City, Nevada are based on trough systems.

A parabolic (solar) dish system consists of a single parabolic reflector which concentrates light at the focal point of the reflector, which tracks the Sun along two axes. Of all the CSP technologies, parabolic dish systems are the most efficient. The 50 kW Big Dish in Canberra, Australia is an example of this technology. The Stirling solar dish combines a parabolic concentrating dish with a Stirling heat engine which drives an electric generator. The term “Stirling” refers to the fact that the device operates on a simple heat-engine principle. Stirling solar energy production is more efficient than photovoltaic cells and the technology has a longer lifetime.

A solar power tower consists of an array of dual-axis tracking reflectors (heliostats) that concentrate light on a central receiver at the top of a tower. The receiver contains a working fluid to absorb the heat, and can be seawater. The working fluid in the receiver is heated to 500-1000 °C and then used as a heat source to generate power or to store energy. Concentrating thermal power is the main technology proposed for a cooperation to produce electricity and desalinated water in the arid regions of North Africa and Southern Europe by the Trans-Mediterranean Renewable Energy Cooperation Desertec.

The potential and future of concentrated solar power was investigated and reported from a study by Greenpeace International, the European Solar Thermal Electricity Association, and the International Energy Agency's SolarPACES group. Remarkably, it was concluded that concentrated solar power could provide 25% of the world's energy needs by 2050. To achieve this, however, would require an increase in world investment would from 2 billion euros to 92.5 billion euros over that same time interval, although it further predicted that the price of electricity would drop from the present 0.15 - 0.23 euros currently per kilowatt, to 0.10 - 0.14 euros a kilowatt.

We always hear this, however, in the inauguration of all new technologies that the power production by their means will be cheaper, most notably (or notoriously) atomic power that was supposed to provide “electricity too cheap too meter”. Spain is the world leader in concentrated solar power technology, with more than 50 projects underway. The Desertec scheme has been described as being part of an overall intention to create "a new carbon-free network linking Europe, the Middle East and North Africa".

Related Reading.
C.J.Rhodes, "Solar Energy: Principles and Possibilities", Science Progress, 2010, Vol. 93, 37 - 112.

Thursday, June 24, 2010

Slovakia: a Sustainable Country?

The Icelandic volcano which prevented my travelling to Slovakia as planned last April, appears to have fallen sufficiently silent to at least provide a window through which I could pass, on my cheap Ryan Air flight to Bratislava from London Stansted at a cost of about "fifty quid" ("around "eighty bucks", I believe). Thus I was able to deliver two lectures on the World Energy conundrum, one at the Slovak Technical University in Bratislava and the other at the "University of Constantine the Philosopher" in Nitra. Constantine is better known as Saint Cyril, who along with his brother Methodius, devised the Cyrillic script which I believe was the first successful effort to inscribe as a written and unified language the many spoken tongues of that gargantuan region that for many years in the West we knew simply as "Russia".

It is of course far more than that, as is "Europe", as an admixture of cultures, philosophies, pains, joys and endurances that forge the individual character of each and all nations, but unifies us all in the spirit of the Human Family, when we realise by our communications with one another from across the world that our fundamental qualities, both good and bad are much cut from the same block of collective DNA.

Slovakia, unlike its sister, the Czech Republic, from whom it was estranged in 1993 in the carving-up of what was Czechoslovakia, converted to the Euro within the last two years. They may regret this now, as such a conversion came at a large fiscal outlay, and the value of their cash-holdings is falling as the Euro descends. The British Pound seems to be rising against the Euro but the truth is that both are in free-fall, and the Euro has fallen more rapidly of late, with an uncertain landing for either.

Given the uncertain aspect of world finance, there is little I can speculate on with the authority needed. That said, even my financial adviser is somewhat at a loss as to where it is all going but agrees that the joker in the pack in likely to be the availability and price of oil. The major oil companies appear to have come out of denial about the reality of peak oil, and would not do so had not their business interests been threatened otherwise, so the whole concept can be taken seriously and as real, whatever the outcome of it will be.

In my lectures, I stressed much of the ideas aired in this blog, which has been a challenge and recasting of perspectives that I had when I began writing it about five years ago, and I have periodically changed my mind, finally believing that optimism over the energy problem is at best patchy, and cheerier views of it are no more than occasional light-relief from despair while one contemplates an entirely different way of living, in the effort to use less energy rather than making relentlesly more or even propping-up the status quo with renewables and so on.

Peak oil in a nutshell impacts on three things: (1) a globalised world run on oil, (2) the whole of manufactured goods, (3) industrialised farming. To cut through and integrate the attendancies of this it seems that a nation like the UK, which is heavily industrialised and dependent on imports for one third of its food, is in a more vulnerable condition than Slovakia which is practically self-sufficient although it strains to industrialise, and is urgently building infrastructure, especially new roads, to join the global club. Slovakia has its own renewable energy projects too, for example at the STU in Bratislava, but if, as I believe we will none of us be able to match our colossal fossil and nuclear energy bill by renewables, to be in a condition of "less advancement" and hence lower dependency on provision of essentials such as food (not the latest I-pod etc.) brought-in by oil-based transport and farming methods, might prove to be a considerable advantage.

I am beginning to think that the enlargement nations of the EU, i.e. Eastern Europe may have much to offer over their western counterparts. As a Slovak colleague commented on the struggle for the British government as it slashes the bills here and there to get the national debt down, "well, we have always been poor in Slovakia". In the UK, we will be poor too, but that downward transition will be tough to bear, tumbling down from the "progress" we have been given as read. In a sense, Eastern Europe is the future image of Western Europe. It is at least a sustainable picture.

Wednesday, June 02, 2010

A Fuel Cell that Runs on Air and Water.

It seems too good to be true that water can be used as a fuel, but in a recent paper, a fuel-cell has been described which runs on water and air, in which you don't actually "burn" water but a concentration gradient of water is established between the two electrodes allowing entropy rather than enthalpy to drive the energy output from the cell. The power output is small, orders of magnitude lower than from hydrogen or methanol fuel cells, but the supply and handling of these flammable fuels is avoided. It is proposed that the cell might be used in applications which require relatively low power consumption, for example sensors of various kinds or emergency signalling units, and that the devices might be used best in desert or warm coastal regions where the water is readily evaporated from the cell, thus maintaining its concentration gradient.

On one side of the cell (anode), the reaction 2H2O ---> O2 + 4H+ + 4e- occurs;

while on the other (cathode), the reverse process occurs: O2 + 4H+ + 4e- ---> 2H2O.

The two electrodes, cathode and anode, are separated by a polymer electrolyte membrane which permits protons to cross to reach the cathode while the electrons are made to flow as part of a circuit to carry an electrical current.

The authors note that such a concentration cell avoids the logistic difficulties of using hydrogen gas; nonetheless for an application such as transportation the far greater power output of a hydrogen cell is necessary, and the provision of "green" hydrogen in quantity. All types of fuel cell also require platinum in quantity, the demand for which already exceeds world production of "new" platinum.

Thus the "prediction" by Jules Verne in his novel "Mysterious Island", published in 1874, as espoused by the fictional engineer, Cyrus Smith, "I believe that water will one day be used as a fuel, that the hydrogen and oxygen of which it is constituted will be used, simultaneously or in isolation, to furnish an inexhaustible source of heat and light, more powerful than coal can ever be. Water is the coal of the future.", remains some way off.

A very interesting piece of science, however.

Related Reading.
"A fuel cell that runs on air and water," A. M. Dreizler and E. Roduner, Energy and Environmental Science, 2010, 3, 761
DOI: 10.1039/c001381a