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  • Water power

    Water power


    Main article: Hydropower

    Energy in water (in the form of kinetic energy, temperature differences or salinity gradients) can be harnessed and used. Since water is about 800 times denser than air,[26][27] even a slow flowing stream of water, or moderate sea swell, can yield considerable amounts of energy.


     





    One of 3 PELAMIS P-750 Ocean Wave Power engines in the harbor of Peniche, Portugal

    There are many forms of water energy:



    • Hydroelectric energy is a term usually reserved for large-scale hydroelectric dams. Examples are the Grand Coulee Dam in Washington State and the Akosombo Dam in Ghana.
    • Micro hydro systems are hydroelectric power installations that typically produce up to 100 kW of power. They are often used in water rich areas as a Remote Area Power Supply (RAPS). There are many of these installations around the world, including several delivering around 50 kW in the Solomon Islands.
    • Damless hydro systems derive kinetic energy from rivers and oceans without using a dam.
    • Ocean energy describes all the technologies to harness energy from the ocean and the sea:


      1. Tidal motion in the vertical direction — Tides come in, raise water levels in a basin, and tides roll out. Around low tide, the water in the basin is discharged through a turbine, exploiting the stored potential energy.
      2. Tidal motion in the horizontal direction — Or tidal stream power. Using tidal stream generators, like wind turbines but then in a tidal stream. Due to the high density of water, about eight-hundred times the density of air, tidal currents can have a lot of kinetic energy. Several commercial prototypes have been built, and more are in development.


      • Wave power uses the energy in waves. Wave power machines usually take the form of floating or neutrally buoyant structures which move relative to one another or to a fixed point. Wave power has now reached commercialization.

  • The Geysers (Geothermal Power)

    The Geysers


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    The West Ford Flat power plant is one of 21 power plants at The Geysers

    The Geysers, a geothermal power field located 72 miles (116 km) north of San Francisco, California, is the largest geothermal development in the world. It is currently outputting over 750 MW. The Geysers consists of 22 separate power plants that utilize steam from more than 350 producing wells. [1] The Calpine Corporation operates and owns 19 of the 22 facilities. The other three facilities are operated by the Northern California Power Agency and the Western GeoPower Corporation.





    [edit] Description

    The Geysers geothermal development spans an area of around 30 square miles (78 km²) in Sonoma and Lake counties in California, located in the Mayacamas Mountains. Power from The Geysers provides electricity to Sonoma, Lake, Mendocino, Marin, and Napa counties. It is estimated that the development meets 60 percent of the power demand for the coastal region between the Golden Gate Bridge and the Oregon state line.[1]

    Steam used at The Geysers is produced from a greywacke sandstone reservoir, that is capped by a heterogeneous mix of low permeability rocks and underlaid by a Felsite intrusion.[2] Gravity and seismic studies suggest that the source of heat for the steam reservoir is a large magma chamber over 4 miles (7 km) beneath the ground, and greater than 8 miles (14 km) in diameter. [3]

    Unlike most geothermal resources, the Geysers is a dry steam field, which means it mainly produces superheated steam. Because the power plant turbines require a vapor phase input, dry steam resources are generally preferable. Otherwise, a two-phase separator is required between the turbine and the geothermal wells to remove condensation that is produced with the steam.

    [edit] History

    The first recorded discovery of The Geysers was in 1847 during John Fremont‘s survey of the Sierra Mountains and the Great Basin by William Bell Elliot. Elliot called the area “The Geysers,” although the geothermal features he discovered were not technically geysers, but fumaroles. Soon after, in 1852, The Geysers was developed into a spa for The Geysers Resort Hotel, which attracted the likes of Ulysses S. Grant, Theodore Roosevelt, and Mark Twain.[4]

    [edit] Future

    The Geysers electrical plant reached peak production in 1987, at that time serving 1.8 million people. Since then, the steam field has been in gradual decline as its underground water source decreases. Currently, the Geysers produce enough electricity for 1.1 million people.

    Techniques developed from Enhanced Geothermal Systems research will increase the production of the region in the future. By reinjecting greywater from the nearby city of Santa Rosa, existing wells will be recharged. This water will be naturally heated in the geothermal reservoir, and be captured by the existing power plants as steam. The project should increase electrical output by 85 MW, enough for about 85,000 homes.[5]

     

  • Meltdown is a warning the world can’t afford to ignore

    Meltdown is a warning the world can’t afford to ignore


     





    The release of America’s spy satellite images of Arctic sea ice provides unexpected, dramatic new evidence about the dangers of global warming.


    These visions of dwindling ice cover confirm that changes in climate in the planet’s high latitudes are progressing much faster than originally expected. And what happens there is bound to have an impact elsewhere on our overheating world, in particular to its rising sea levels.


    It is not the actual loss of Arctic sea ice that is the danger, of course. Its melting will add nothing, directly, to rises in sea levels. But its dwindling will almost certainly have a profound knock-on effect – mainly on the great ice sheets that cover Greenland and Antarctica. Without sea ice to prop them up at their edges, these sheets will break apart at faster and faster rates and tip more and more ice into the oceans. And once changes have been triggered at their edges, these will be transmitted into the hearts of these great glaciers at remarkably fast rates, scientists predict.


     


    And here lies the threat to Earth. The destruction of the ice sheets of Antarctica and Greenland will feed vast amounts of meltwater into the oceans, far more than has been calculated until very recently. For example, the last report of the Intergovernmental Panel on Climate Change contained little input from melting ice sheets in its estimates and concluded, instead, that sea-level rises would be constrained to around 20 to 60 centimetres by the end of the century.


    That figure now looks uncomfortably optimistic and current estimates put the likely rise at one metre or more by 2100 – a figure backed by the US Geological Survey, which this year warned that rises could reach as much as 1.5 metres. As a result, low-lying areas, including Bangladesh, Florida, the Maldives and the Netherlands, will undergo catastrophic flooding, while in Britain large areas of the Norfolk Broads and the Thames estuary could disappear. In addition, cities including London, Hull and Portsmouth will need new flood defences.


    And that is just the beginning. No matter what we do about carbon dioxide emissions – the key cause of this heating and melting – the world will continue to warm and its sea levels to rise beyond 2100. Reversing global warming will be a very long process. However, we have, if nothing else, been warned.

  • Canberra first to see electric car network

    Canberra first to see electric car network


    Posted 47 minutes ago



    The ACT Greens have welcomed moves to set up an electric car network in Canberra.


    Infrastructure provider Better Place Australia has chosen Canberra as the first site in the country to roll out its network of charge stations and battery swap points.


    The company will start building the network in two years and expects cars to come online in 2012.


     


    Greens MLA Amanda Bresnan says it is a positive step, but only part of the solution.


    “This is one thing we can do, but obviously public transport is that other major thing we have to do because not everybody is going to be able to afford to purchase electric cars,” she said.


    “We need to actually be putting in infrastructure that addresses the larger part of the population and also people on lower incomes.”

  • We’re living longer but even that is worrying us

    But
    what if it is a good thing? To start with, there is no sweet spot with
    life expectancy. The orthodoxy is: the higher, the better. In Zimbabwe
    a combination of HIV/AIDS, starvation, bad sanitation and the
    wellspring of these ills, poor governance, has cut life expectancy at
    birth to 40 years. In Japan, the country with the highest life
    expectancy, you can look to live to 82. Nowhere in any census or policy
    document will you see anyone saying: “Some kind of midpoint would be
    nice . . .  61?” This is for a number of reasons, the most obvious being
    that people tend not to want to die.

    The rise
    in the number of the old is a massive human success story: life
    expectancy increases because of better education, greater wealth, lower
    infant mortality, better healthcare, less disease, the reduction of
    armed conflict, and the development of technology and its application
    in pursuit of good. It is, frankly, insane to look at an ageing
    population and not rejoice. Why do we even have a concept of public
    health, of co-operation, of sharing knowledge, if not to extend life,
    wherever we find it?

    The problem, then, is not age as such
    but the proportion of the aged: not only will the old outnumber the
    young globally but, in 11 major nations, the population is ageing while
    numbers decline – an unprecedented combination. It will lead to a very
    substantially increased “older dependency ratio”, which is taken,
    inexorably, to be damaging to economies.

    Again, this
    presentation ignores benefits that are much more significant than any
    country’s gross domestic product. It is a consensus among
    environmentalists that a decline in human fertility will, if not solve
    the planet’s problems, at least give us some breathing space in which
    to solve them. The spectre of Malthus, the world’s most famous Guy Who
    Was Wrong, muddies the water unnecessarily. Yes, he was wrong; and yes,
    the neo-Malthusian Paul Ehrlich fell victim to overblown predictions of
    catastrophe in the 1960s.

    In The Population Bomb he
    wrote: “The battle to feed all of humanity is over. In the 1970s the
    world will undergo famines – hundreds of millions of people are going
    to starve to death.” That kind of drama did not transpire but he was
    not far off: 300 million people have died of hunger or related causes
    since 1967.

    But just because burgeoning fertility has not
    been the catastrophe some have claimed, it does not mean we should not
    take heart from its decline. And if fertility does fall, then of course
    this will tip the balance in favour of the old.

    Another
    difficulty with those “worrying” older dependency ratios is that they
    are all based on a traditional retirement age – which most of us know
    to be outdated. For Britain, the country’s National Association of
    Pension Funds points out that women’s eligibility for the state pension
    was reduced from 70 to 60 in 1940. The pre-war situation was the
    hardboiled if bizarre one that life expectancy as a woman was 64, and
    yet you did not qualify for state aid until six years later. For men it
    was moderately worse. Their life expectancy was 59 in 1941, and their
    eligibility for state pension was not brought down to 65 until 1948.
    The state has never expected to support people for 21 years before
    death; rather, for a year or two, or hopefully minus six.

    The
    counter-argument is that as life expectancy rises so do chronic and
    degenerative conditions, so that people just are not well enough to
    work in the five years before their death, as they were when life
    expectancy was lower.

    This is contested territory, though,
    and the spectre of decades of disability at the end of life is not
    borne out by the figures. Many prefer the “dynamic equilibrium”
    prediction, in which the factors extending life – a healthier
    lifestyle, faster detection of conditions, better treatment – also
    minimise disability; and, where there is ill health, it is compressed
    into a short period before death.

    Our ageing world, in
    other words, is brilliant news. This is what we have been working
    towards for as long as the concept of working towards anything has
    existed. The response so far makes me think that maybe there is just no
    pleasing a statistician.

    Zoe Williams is a columnist with The Guardian, in which this article first appeared.

  • Carribbean Reefs Face Severe Summer Threat

    July 22, 2009, 5:03 pm

    Caribbean Reefs Face Severe Summer Threat


    By Andrew C. Revkin






    Coral reefs in a broad swath of the Caribbean face a substantial risk of severe bleaching and die-offs through October, the National Oceanic and Atmospheric Administration said on Wednesday in its latest  Coral Reef Watch report.


    Similar conditions may develop in the southern Gulf of Mexico and central Pacific, the agency said. But the report said the widest area of high risk was in the southern Caribbean, from Nicaragua’s east coast across the south coasts of Haiti and the Dominican Republic and from Puerto Rico south along the Lesser Antilles. Rising ocean temperatures are contributing to the risk, the report said, noting that the National Climatic Data Center reported that in June the world’s  ocean surface temperature was the warmest on record.


     


    From the report:



    Scientists are concerned that bleaching may reach the same levels or exceed those recorded in 2005, the worst coral bleaching and disease year in Caribbean history. In parts of the eastern Caribbean, as much as 90 percent of corals bleached and over half of those died during that event.


    The forecast said there was substantial risk of bleaching in parts of the Pacific Ocean, as well, and noted that this did not include the extra heat anticipated from a developing El Niño warming of the tropical Pacific.