Sabtu, 13 Februari 2010

Circuit uses light to power itself

Scientists have created a circuit that can power itself, as long as it's left in a beam of sunshine.
Created by scientists from the University of Pennsylvania, the world's first photovoltaic circuit could eventually power a new line of consumer devices or even model the human brain.
"This has the potential to create a new generation of optical and electronic devices," says Dr Dawn Bonnell, a scientist from the University of Pennsylvania who co-authored a recent ACS Nano paper describing the research. "The touchscreen of your computer could act as both the electrical charger and the computer chip."
Bonnell and her colleagues can only coax minuscule amounts of electricity from their photovoltaic circuits, far too little to power consumer electrical devices. But those amounts could quickly skyrocket.
"We would have one amp with one volt in a sample the diameter of a human hair and an inch long," says Bonnell. "If the efficiency scaled up without any additional limits."
There are plenty of other ways Bonnell can squeeze more electricity from light. About 10% of the photovoltaic circuits on a glass side work. Increasing that number will boost the power output.
Yet another way to get more power is by turning their 2D structures into 3D structures. Stacking multiple layers of light-collecting and electricity-using circuits would also boost power.
The photovoltaic circuit developed by Bonnell and her colleagues is a scientific breakthrough, not a technological one. These new circuits will most likely never replace their silicon counterparts.

Jumat, 12 Februari 2010

Preparations for six AP1000s

Chinese planners are moving ahead with three new nuclear power plants based on AP1000 reactors - the first to be developed after technology transfer from Westinghouse.

The US-based reactor vendor is already constructing pairs of AP1000 reactors in China with its partner Shaw at Sanmen and Haiyang, but these new units are to be the first built independently after the technology transfer that was part of Westinghouse's contract. They are also China's first nuclear power plants not located on the coast.

The sites are Xian'ning, Hubei province, Tauhuajing in Hunan, and Pengze in Jiangxi. All have been given the go-ahead for final design and initial construction work, such as site clearance, for the first two reactors at each site. Main construction is set to start on all three sites around this time next year, with commercial operation following around 2015.

A further wave of AP1000 build will include at least one other pair of units at each of the above sites, while up to six new locations are already pencilled in for AP1000 development.

Each of the latest sites is to be led by a different Chinese firm: Xian'ning by China Guangdong Nuclear Company; Taohuajing by China National Nuclear Company; and Pengze by China Power Investment Corporation. Transferral of the AP1000 technology is being carried out by State Nuclear Power Technology Corporation, which will now take the engineering lead on new AP1000s.

Nuclear production line

Having developed its own reactors and imported a wide range of units from international vendors, China is now focused on two designs for mass deployment: the CPR-1000, developed from French 900 MWe-class units imported in the late 1980s, and the AP1000.

According to plans, fleets of these reactors will be constructed with exponential speed for China to achieve a nuclear capacity of over 60 GWe by 2020 - and as much as 120-160 GWe by 2030. Such an achievement would make China by far the biggest generator of nuclear power in the world.

Successive CPR-1000 projects have featured increasing amounts of local engineering and now around 90% of plant components are sourced from Chinese firms. The AP1000 features modular construction and China has quickly set up specialised nuclear facilities to produce the very large modules - effectively creating a production line for nuclear power plants.

Selasa, 09 Februari 2010

Wow, China is serious about clean energy !

Wind Power

The world’s largest wind power project is currently in Texas (with a capacity of 782 MW), but China“is in the midst of building a wind corridor that could grow to a staggering 20,000 MW, 25 times the size of Texas’ Roscoe Wind Farm.” (emphasis mine) This wind farm in China is expected to have a capacity of 5,000 MW by the end of this year.

Solar Power

Additionally, China just “announced it would build a 2,000 MW solar thermal project, five times bigger than the current largest one, California’s Solar Energy Generating System.”
And in the fall, China announced plans to build a 2000 MW solar photovoltaic farm, “33 times bigger than the world’s largest today, a 60 MW farm in Spain.” (empasis mine)
Washington State thought it would take the world title with a planned 75 MW solar PV plant — think again. It may complete this plant before China’s, but don’t think that it will be the big news for long.
See article

Quote interesting response:

  • Europe has big wind ambitions too. Consider this ” link” and those projects are not with expected load factors under 20 but well above 30.  Almost 100 GW of off-shore wind projects are under consideration in the North and Baltic Seas alone. 1 GW (more) of off-shore windmills are to be connected to the grid in 2010 in europe.
  • .....a study by the Energy Foundation found that “Residential and commercial rooftop space in the U.S. could accommodate up to 710,000 MW of solar electric power,” which is 75% of the nation’s current electric consumption.  
  • You left out China’s biggest source of new clean power:   “Additional reactors are planned, including some of the world’s most advanced, to give a sixfold increase in nuclear capacity to at least 60 GWe or possibly more by 2020, and then a further substantial increase to 160 GWe by 2030.”    And a watt of nuclear capacity is worth about three of wind or solar.

    Minggu, 07 Februari 2010

    Global warming makes trees grow at fastest rate for 200 years

    By Steve Connor, Science Editor
    Tuesday, 2 February 2010

    Trees across North America are growing at an unprecedented rate as a result of higher temperatures and CO2 levels
    Forests in the northern hemisphere could be growing faster now than they were 200 years ago as a result of climate change, according to a study of trees in eastern America.
    The trees appear to have accelerated growth rates due to longer growing seasons and higher concentrations of carbon dioxide in the atmosphere. Scientists have documented the changes to the growth of 55 plots of mixed hardwood forest over a period of 22 years, and have concluded that they are probably growing faster now than they have done at any time in the past 225 years – the age of the oldest trees in the study.
    Geoffrey Parker, a forest ecologist at the Smithsonian Environmental Research Centre in Edgewater, Maryland, said that the increase in the rate of growth was unexpected and might be matched to the higher temperatures and longer growing seasons documented in the region. The growth may also be influenced by the significant increase in atmospheric carbon dioxide, he said.
    Higher concentrations of carbon dioxide and extended growing seasons could be favourable for agriculture in some parts of the world, mainly in the northern hemisphere. The study in Maryland suggests that the extra growth in trees could help to act as a more efficient carbon "sink", which could offset the carbon dioxide being added to the atmosphere by the burning of fossil fuels.

    Methane on ice: a climate shock in store?

    Known frozen methane sites around the world: a nasty climatic surprise in store? (Pic: Oak Ridge National Lab)
    Anna Salleh - ABC Science Online
    Vast stockpiles of frozen methane on the seafloor are more unstable than previously thought, and their sudden release may have been linked to global warming in the past.
    Led by Dr Kai-Uwe Hinrichs of the Woods Hole Oceanographic Institution in Massachusetts, USA, the new evidence is published in this week's issue of Science.
    The researchers examined the by-products of ancient methane-using bacteria in sediments of the Santa Barbara Basin, off the coast of California. They found evidence that methane trapped in ice crystals (known as methane hydrates) on the seabed was released into the water 44,000 years ago - at the same time there was a rapid, but as yet unexplained, rise in global temperatures.
    Methane is a potent greenhouse gas, about 10 times more powerful than carbon dioxide. Scientists estimate that approximately 3,000 times the volume of methane in the atmosphere is currently trapped in hydrates at the bottom of the sea.
    While conclusive proof is still lacking that the seabed methane released into ocean sediments 44,000 years ago reached the atmosphere, the fact that the hydrates are not as stable as scientists believed raises the possibility that they could be a climatic time-bomb in the future.

    Scientists confirm positive CO2 feedback

    Anna Salleh
    ABC, Thursday, 28 January 2010

    Scientists have calculated the most accurate estimate to date on how rising temperatures will trigger the release of more CO2 from the ocean and land, further amplifying the greenhouse effect.
    But some experts warn it still won't tell us exactly what will happen to the planet as CO2 in the atmosphere continue to rise.
    Palaeoclimatologist Dr David Frank of the Swiss Federal Research Institute  in Birmensdorf and colleagues report their findings in today's issue of the journal Nature .
    "It's well known that the CO2 increase will cause a temperature increase," says Frank.
    "But what also happens is that you have increased temperatures that causes the ocean and the terrestrial biosphere to also release more CO2 into the atmosphere."

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