The Promise of Wireless Charging Technologyquarterly
Total Page：16
File Type：pdf, Size：1020Kb
Cars that can Scrubbing CO2 How pacemakers park themselves from the air keep the beat TechnologyQuarterly March 7th 2009 Cutting the final cord The promise of wireless charging Contents On the cover Wireless networking for laptops is commonplace, and mobile phones let people do all sorts of amazing things while on the move. But one stubborn cable remains: the power lead for recharging portable devices’ batteries. New technologies now aim to cut this nal cord: page 12 Shifting gears Monitor 2 Greener jet engines, revamping lead•acid batteries, biofuel from co ee, solar power from balloons, growing articial bone marrow, a mousetrap for bacteria, optical memory chips, Aviation: Green jet engines, able to power aircraft while producing fewer using lasers in farming, smart emissions, are under development. Which design will prevail? threads, rotating buildings, reading online reviews, and HAT jet engines have evolved over the them, and this in turn means they are alternate•reality games Tpast few decades will be apparent to quieter and use less fuel. any seasoned air traveller. Early jet en• But the aviation industry has set itself a Rational consumer gines had narrow inlets and were very tough target: a 50% reduction in fuel con• noisy, but as the diameter of the fans at the 11 Self•parking cars sumption by 2020, to cut CO2 emissions in Find a space, then click front increased, the engines became quiet• half. Building more aerodynamic aircraft er. Compared with a rowdy 1960s jet, a and operating them more eciently (by modern turbofan is some 80% quieter and Wireless charging reducing air•trac•control delays, for burns as little as half as much fuelthus instance) could produce about two•thirds 12 Adaptor die producing fewer greenhouse gases. But of those savings. But the rest will have to Cutting the nal cord with regulation of aviation emissions come from better engines. Research in likely in the coming years in order to com• areas such as new materials and improved Carbon capture bat climate change, jet engines must be• blade design will provide incremental 14 Scrubbing the skies come cleaner and more frugal still. improvements to high•bypass turbofans. A remedy for climate change? When a jet engine is running, a fan at But it is unclear whether these will be the front draws in air, which is then com• enough to achieve the required fuel sav• Case history pressed and burned with fuel to produce ings. A completely new type of engine 16 The rhythm of life hot, rapidly expanding gases which roar may be needed. A brief history of pacemakers out of the back. On the way out, these The solution devised by Pratt & Whit• gases drive a turbine which is connected ney (P&W), a division of United Technol• Video analysis to the fan via a shaft, thus drawing in more ogies, is a geared turbofan engine called air and keeping the process going. But not PW G 19 Computers that can see the PurePower 1000 . Unlike a con• The latest in machine vision all the air passing through an engine ventional turbofan, it uses a gearbox needs to go through the turbine. Over the rather than a shaft between the fan and years the fans have grown larger and the Crowd modelling the turbine. Turbines run most eciently fraction of the air that passes through the at high speeds, and fans at low speeds, so 21 Mob rules turbine has fallen. The latest high bypass turbofan engines have to compromise Simulating crowd behaviour turbofans, such as the Rolls•Royce Trent, between the two, because the engine’s push around nine times more air around design requires them to turn at the same Brain scan the core of the engine than through it. speed. A gearbox, however, allows the 23 The internet’s librarian Such high•bypass engines rely on a bigger turbine to operate at a high speed while A prole of Brewster Kahle, but slower•moving volume of air to pro• driving the fan at a lower speed. In Febru• archivist and idealist vide thrust. Their turbines can be smaller, ary P&W said that in tests, this design had since not all the air is passing through proved capable of double digit improve• 1 The Economist Technology Quarterly March 7th 2009 Monitor 3 2 ments in fuel eciency and emissions, dioxide and a negative electrode of metal• and a 50% reduction in noise. lic lead. These are immersed in an electro• Some airlines, however, are wary of lyte of dilute sulphuric acid. Car batteries gearboxes. They worry that replacing a Recharged tend to have thin electrode plates, which simple shaft with a complex gearbox will allows a lot of energy to be discharged increase maintenance costs and make it quickly, but only for a short period of time. more likely that something will go wrong. That is ne for turning a starter motor, but P&W disagrees. Bolted under the wing of it is not so good for powering an electric an Airbus A340 as part of its test pro• Energy: There is life in a 150•year•old motor intended to move a car any dis• gramme, the PW1000G endured more battery technology yet, it seems, as tance. Moreover, lead•acid batteries can be than 75 hours of operation, including venerable lead•acid batteries are ruined if they are discharged completely, many extreme manoeuvres, and proved as many motorists have discovered to its durability, says Bob Saia, who is in given a modern overhaul their cost when trying to start their cars on charge of engine development at P&W. EAD•ACID batteries seem to have been icy mornings. Lead•acid batteries with Moreover, he adds, the gearbox is made Laround for ever. They were invented in thicker electrodes can tolerate such deep from the same kind of steel that is already 1859 by Gaston Planté, a French physicist, discharges better than those with thin used in the small gearboxes that take and have done sterling work over the ones, but only at the expense of making a power from turbofans for aircraft systems. decades starting car engines and pow• heavy battery even heavier. P&W will now use the data gathered ering slow•moving vehicles such as fork• In Axion’s new battery the negative from its test ights to nalise the engine’s lift trucks and milk oats. Compared with electrode is replaced with one made from design. The PW1000G is due to enter the newer energy technologies that are activated carbon, a material used in su• service in 2013 powering two new short• now sweeping the world, however, they percapacitors. Normal capacitorsthose haul aircraft being built by Mitsubishi and look old•fashioned and a bit frumpy. that power the ashguns in cameras for Bombardier. It could also be scaled up for These days the catwalk is crowded with instancecan be charged and discharged use on bigger aircraft. Some in the in• nickel•metal hydride and lithium•ion rapidly, but cannot store much energy. dustry think geared turbofans could even• batteries, showing o their ability to pack Supercapacitors are meatier versions that tually reduce fuel consumption by 20•25%. lots of energy into a small space and deliv• are able to hold a reasonable amount of There is another way to build a greener er a steady current over a long period. The energy, and can take it in and release it jet engine: by bypassing the turbine to an fact that these modern batteries are also quickly. Some, indeed, are already used in even greater extent, with an open rotor. lighter (lead is, after all, one of the densest tandem with the lithium•ion batteries in This is a bit like going back to propellers. A elements in the periodic table) has made electric cars to boost acceleration and number of designs use two rings of stub• them the obvious choices for powering recapture energy during so•called regen• by, counter•rotating blades made from truly serious electric vehicles, as opposed erative braking. Axion’s plan, therefore, is composite materials. Unlike the blades on to the ones that potter about in ware• to have the best of both worlds by build• old•fashioned propeller engines, these houses and on suburban streets. ing a hybrid battery that is based on lead• blades spin around at the back of the But it is a mistake to dismiss something acid/carbon (PbC) chemistry. engine. Rolls•Royce and General Electric just because it is old. Another way of The carbon, which is protected within (GE) are studying this approach, though looking at things is that lead•acid batteries a sandwich of other materials, is more they are also keeping their options open are tried and trusted; they may just need a e ective than metallic lead at exchanging by working on improvements to conven• bit of pepping up. Axion Power, a rm protons with the acid during charging and tional turbofans, too. GE carried out test based near Pittsburgh, Pennsylvania, has discharging. In tests, Axion says, its PbCs ights with an open•rotor engine in the found that the ideal tonic is carbon. withstood more than 1,600 charges and 1980s, and reckoned it would use 30% less A conventional lead•acid battery is deep discharges before failure, which is fuel than similar•sized engines of the time. made up of a series of cells, each of which three times better than standard lead•acid But the engine was noisy, and there were contains a positive electrode made of lead batteries that are specically designed for 1 concerns about what would happen if one of the blades broke o and tore into the aircraft’s fuselage.