五大妙招巧获清洁能源
By now， we’re all familiar with the mainstays of renewable energy. They’re the solar panel arrays and massive turbine systems that span great lengths， collecting energy from the sun， wind and water and churning out megawatts of energy. It’s these behemoths that we point to as bellwethers of a future where the world no longer depends on fossil fuels.
[2] But recently， some researchers have started to tinker with more subtle ways to harvest energy. They’re mostly unconventional ideas， such as layering tiny and transparent solar cells onto a phone’s touchscreen or a sound conversion technology that allows it to recharge simply by talking into it.
[3] Though these out-of-box approaches1out-of-box approach创造性方法。don’t receive nearly as much attention as some of the more elaborate industrial-scale projects， they may well turn out to be game-changers2game-changer改变游戏规则的人，即创新的人。in their own right. As such， here are instances where eeking out even a modest amount of energy may make a real difference:
1. Infrastructure power
[4] Hydroelectric power came about as a way to take advantage of the enormous fl ow of energy produced from reservoirs. However， the same principle can also work wherever there’s a strong and steady stream of water， whether it be dams or sewage pipes.
[5] Catching on to this fact， the city of Portland is testing a power-generating water turbine system specially suited for municipal drainage technology， developed by local start-up LucidEnergy， is projected to contribute up to 1，100 megawatts of electricity annually， enough to power approximately 150 homes.
[6] Roadways are also hotspots for untapped energy. In 2011， a research team were able to harvest energy from the vibrations produced by moving cars by coating a section of the road surface along a Dutch highway with energyabsorbing piezoelectric the course of three months， they found that， on average， net electrical output was suf fi cient to run the motion sensors on a traf fi c light.
2. Ambient energy
[7] To ensure coverage over a given area， WiFi hubs blast signals in all directions. Satellite transmission is somewhat similar， scattering signals across a wide region. As a result， a lot of energy is wasted.
[8] But there are ways to recover some of these lost signals. Researchers at Duke University have converted them into electricity. Employing a special microwave-scavenging metamaterial，they were able to build a device capable of generating up to 7.3 volts. The goal is to eventually incorporate the technology into cell phones， which in many instances can use a little extra juice.
[9] While the idea has been kicked around for some time， the challenge has been fi guring out how to implement it on a consumer level. RCA3Radio Corporation of America的简称，美国无线电公司。， an electronics brand， caused a bit of stir back in 2010， when representatives unveiled an early prototype of a USB dongle they claimed can give laptops a power boost by trapping stray WiFi signals and storing them as converted energy in an internal battery. However，the Airnergy charger4Airnergy charger无线信号充电器。was never released.
3. Body energy
[10] Every person is， in some respect，a walking power plant. Even at rest， the human body generates as much energy as a 100 watt light bulb. Much of this dissipates in the form of heat， though a coat with good insulation properties can momentarily trap enough of it for us to stay comfortably warm at times when temperatures are unbearably cold.
[11] With that line of thinking，Jernhusen， a Swedish real estate firm，had an ambitious proposal. In 2008， the group outlined a plan to construct an office building in Stockholm equipped with a unique heating system that so happened to be powered by the excess body heat of 250，000 some commuters that pass though the nearby central train station each day.
[12] The system， in operation today，is made possible through a series of heat exchangers situated inside the train station’s ventilation system. This is where body heat is converted into hot water and piped in to warm the building. In total， costs are reduced by about 25 percent compared to regular heating systems. And closer to home，the Mall of America in Minneapolis recycles body heat from shoppers to more better regulate the indoor climate.
[13] On a smaller scale， scientists are looking into ways to make good use of energy generated by the body’s internal machinations. Engineers in the United States and China have collaborated on a technology that uses the mechanical energy of a beating heart to pump power to pacemakers. In Boston， a team at the Massachusetts Institute of Technology is developing a tiny chip that pulls in energy from natural processes that take place within the ear canal as a way to extend the long-term implantation of hearing aids.
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