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BP gears up for shot at a relief well
TECHNOLOGY Insight Drilling 5000 metres into the seabed is a last resort, but the only way to stop the oil succeeds in hitting so small a target at such great depths. To direct the drill, BP is using a technique called measurement while drilling (MWD). Accelerometers and magnetometers attached to the drill bit monitor the movement and direction of the well bore and transmit this information back to the surface. The system sends these messages by creating pulses in the flow of mud that is constantly pumped in and out of the borehole to clear away the rock cuttings, says Ken Arnold, who runs KACI, an oil industry consultancy in Houston, Texas. The pulses are created by briefly closing and opening valves in the drill
gerald herbert/getty
IMAGINE drilling into a cylinder just 18 centimetres wide and 5500 metres below the sea floor. That’s the feat BP will have to accomplish if its relief well is to stem the flow of oil from the stricken Deepwater Horizon. “There isn’t anything else you can do,” says Greg McCormack at the University of Texas at Austin. All previous attempts to plug the leaking well have failed. A relief well is intended to provide an opening into the casing of the original well at a point near the oil reservoir. BP is drilling two wells at the same time to avoid lengthy delays if one should fail. The company may also have to try many times before it
Help is on the way, but a relief well won’t be ready until August
pipe to restrict the flow of mud – the resulting pressure fluctuations can be detected by sensors and interpreted by computers on the surface. “They provide the information needed to plot to within 3 metres of where the bit is the whole time,” he says. Once close to their target, the
engineers can home in on Deepwater Horizon’s well by detecting fluctuations in Earth’s magnetic field caused by the steel and concrete foundation that surrounds it. When they do drill a pipe into the original well, they will pump in mud until there is enough to counteract the pressure of the oil and gas in the reservoir. At that point the whole well can be sealed with concrete. So would it be possible to tap this deep-sea oil reserve once the initial well has been sealed? “It’s too early to say,” a BP spokesman told New Scientist. He said the drilling, which began last month, is on track for completion in early August. Helen Knight n
Harness hot electrons to double solar cell efficiency CONSERVATION DEVELOPMENT TRAVEL
Frontier has been operating conservation research programmes throughout the tropics for 20 years. Frontier Volunteers have contributed to some outstanding research leading to the formation of numerous National Parks and a host of effective community-led conservation programmes.
24 | NewScientist | 26 June 2010
SOLAR cells could see a boost in their theoretical maximum efficiency from 31 per cent to 66 per cent, thanks to a novel way of harnessing electrons whose energy is normally lost as heat. The most efficient silicon solar cells turn 25 per cent of the incoming light into electricity, but even with further improvements these cells will reach a theoretical limit at 31 per cent, because incoming light creates large numbers of extremely energetic electrons that lose energy to their surroundings in just a picosecond – too rapidly to be harnessed. In 2001, Arthur Nozik of the National Renewable Energy Laboratory (NREL) in Golden, Colorado, suggested that quantum dots – nanoscale chunks of semiconducting material – could slow the rate at which “hot” electrons lose energy by 1000 times. That’s because the energy levels within quantum dots are widely spaced, making it difficult for electrons to jump between them. The energy levels are closer together in a bulk
semiconductor, so jumping levels and losing energy as heat is easier. Now, Xiaoyang Zhu at the University of Texas in Austin and his colleagues have shown that those longer-lived hot electrons can pass into a wafer, boosting chances of harnessing them. They recorded a change in the optical properties of a titanium dioxide wafer coated with lead selenide quantum
“The hot electrons can pass into a titanium dioxide wafer, boosting chances of harnessing them” dots characteristic of an influx in electrons, but they had engineered the system such that only hot electrons could enter the wafer (Science, DOI: 10.1126/science.1185509). Matthew Beard at NREL, a member of Nozik’s 2001 team, says the work represents “one more step towards the goal of radically increasing solar energy conversion efficiencies”. Anil Ananthaswamy n
gerald herbert/getty
IMAGINE drilling into a cylinder just 18 centimetres wide and 5500 metres below the sea floor. That’s the feat BP will have to accomplish if its relief well is to stem the flow of oil from the stricken Deepwater Horizon. “There isn’t anything else you can do,” says Greg McCormack at the University of Texas at Austin. All previous attempts to plug the leaking well have failed. A relief well is intended to provide an opening into the casing of the original well at a point near the oil reservoir. BP is drilling two wells at the same time to avoid lengthy delays if one should fail. The company may also have to try many times before it
Help is on the way, but a relief well won’t be ready until August
pipe to restrict the flow of mud – the resulting pressure fluctuations can be detected by sensors and interpreted by computers on the surface. “They provide the information needed to plot to within 3 metres of where the bit is the whole time,” he says. Once close to their target, the
engineers can home in on Deepwater Horizon’s well by detecting fluctuations in Earth’s magnetic field caused by the steel and concrete foundation that surrounds it. When they do drill a pipe into the original well, they will pump in mud until there is enough to counteract the pressure of the oil and gas in the reservoir. At that point the whole well can be sealed with concrete. So would it be possible to tap this deep-sea oil reserve once the initial well has been sealed? “It’s too early to say,” a BP spokesman told New Scientist. He said the drilling, which began last month, is on track for completion in early August. Helen Knight n
Harness hot electrons to double solar cell efficiency CONSERVATION DEVELOPMENT TRAVEL
Frontier has been operating conservation research programmes throughout the tropics for 20 years. Frontier Volunteers have contributed to some outstanding research leading to the formation of numerous National Parks and a host of effective community-led conservation programmes.
24 | NewScientist | 26 June 2010
SOLAR cells could see a boost in their theoretical maximum efficiency from 31 per cent to 66 per cent, thanks to a novel way of harnessing electrons whose energy is normally lost as heat. The most efficient silicon solar cells turn 25 per cent of the incoming light into electricity, but even with further improvements these cells will reach a theoretical limit at 31 per cent, because incoming light creates large numbers of extremely energetic electrons that lose energy to their surroundings in just a picosecond – too rapidly to be harnessed. In 2001, Arthur Nozik of the National Renewable Energy Laboratory (NREL) in Golden, Colorado, suggested that quantum dots – nanoscale chunks of semiconducting material – could slow the rate at which “hot” electrons lose energy by 1000 times. That’s because the energy levels within quantum dots are widely spaced, making it difficult for electrons to jump between them. The energy levels are closer together in a bulk
semiconductor, so jumping levels and losing energy as heat is easier. Now, Xiaoyang Zhu at the University of Texas in Austin and his colleagues have shown that those longer-lived hot electrons can pass into a wafer, boosting chances of harnessing them. They recorded a change in the optical properties of a titanium dioxide wafer coated with lead selenide quantum
“The hot electrons can pass into a titanium dioxide wafer, boosting chances of harnessing them” dots characteristic of an influx in electrons, but they had engineered the system such that only hot electrons could enter the wafer (Science, DOI: 10.1126/science.1185509). Matthew Beard at NREL, a member of Nozik’s 2001 team, says the work represents “one more step towards the goal of radically increasing solar energy conversion efficiencies”. Anil Ananthaswamy n