8. Physics News from the Web

8. Physics News from the Web Items selected from the bulletins of the Institute of Physics (UK) and the American Institute of Physics. a) When the Earth's magnetic field flips b) Reeling in cheap plastic solar film c) Department of Energy boost for small nuclear reactors a) When the Earth's magnetic field flips http://physicsworld.com/cws/article/indepth/48929 A 7 minute in-depth audio interview.

French geophysicist Vincent Courtillot discusses why the Earth's magnetic field occasionally flips, explaining how the geological record reveals the planet's history of pole reversal. The Earth's magnetic field provides us with a vital shield from the Sun's deadly rays, as well as enabling compass bearers around the world to find their way. But the field is not as reliable as we first thought. There is strong evidence in the geological record to suggest that many times throughout the Earth's history the north and south magnetic poles have reversed, as the major dipole component of the field has flipped.

How do we know that the Earth's field has reversed direction in the past? Is another reversal likely to occur anytime soon? What processes deep within the Earth might cause these reversals to occur? b) Reeling in cheap plastic solar film http://physicsworld.com/cws/article/news/48926 A UK-based start-up is developing printable, thin-film plastic solar cells aimed at providing affordable electricity to individual dwellings that have no grid connection, such as those in rural Africa. The flexible device's photoactive layer will be a blend of two organic semiconductor materials positioned between metallic electrodes, all sandwiched by plastic substrates.

Slashing costs Eight19, a Cambridge University spin-off firm, is named after the eight min, 19 s it takes sunlight to reach the Earth. The company believes that sheets of the lightweight plastic thin film will slash the cost of transporting and installing solar panels compared with conventional silicon-based solar panels or glass- based thin-film solar cells. This should make it more affordable for farmers and villagers in remote areas, who can fix the sheets to their roofs to power homes that do not have electricity. "Today, 50% of the cost of solar power is the installation, and that's going up as solar costs come down," says Simon Bransfield-Garth, CEO of Eight19. Eight19 plans to start manufacturing the sheets by 2013, using reel-to-reel printing techniques. c) Department of Energy boost for small nuclear reactors http://physicsworld.com/cws/article/news/48927 The US Department of Energy (DOE) will support the construction of three small nuclear reactors at its Savannah River Site in South Carolina. The reactors are designed to generate heat and electricity for use at remote facilities such as mines, oil fields or isolated communities.

The Savannah River Site is a commercial spin-out of the Savannah River National Laboratory that aims to provide the location and nuclear expertise required by firms that are developing nuclear technologies including small modular reactors (SMRs). Such reactors could be built in a factory and shipped to the desired location. Once the fuel is spent, the reactor could be replaced with a new module and the old one could be shipped back to the factory for reprocessing.

Based in Colorado, Gen4 Energy is working on an SMR that is not much larger than a hot tub and that could supply thermal energy at a rate of about 70 MW. That could be converted into about 27 MW of electricity, which would be enough to supply about 20,000 US households. Holtec, based in New Jersey, plans to build a larger modular reactor that can generate 160 MW – which is about 20% of the capacity of a modern large- scale reactor. Meanwhile in Oregon, NuScale has plans for modules that can each generate 45 MW of electricity. The firm expects that up to 12 modules could be co-located to create a 540 MW power plant.