by Matt Johnson
Forecasts about the future of solar energy tend to be rosy and optimistic, but is the solar revolution really a nobody-loses scenario? A study lead by Aixue Hu (2017) titled “Impact of solar panels on global climate” addresses some infrequently mentioned concerns.
It turns out that solar energy systems have consideration-worthy regional consequences. But you may ask: why? Solar panels are not 100% efficient, they are actually fairly far from it. The most efficient solar panels on the market today run at around a 40% efficiency, with some new technologies promising around 60%, however most are much lower. A few issues arise in the conversion of solar energy into electricity. Firstly, a small percent of the solar radiation is reflected, as a result of solar panels’ glare. Then, another few percent are lost in the conversion of direct-current into alternating current and along the transmitting wires to centers of population. The authors estimate the mentioned causes to sum to about a 10% loss. Continue reading
by Matt Johnson
One of the problems that has grappled electrical engineers over the last few decades is the long-distance transmission of power. As the shift towards renewable energy continues, we are finding more and more electricity being generated farther and farther away from consumers. With an unavoidable power loss directly related to transmission distances, engineers have found themselves in a tough situation. The Economist (2017) dives into one technology, ultra-high-voltage direct-current connectors, as a particularly promising solution. Electric power grids were standardized on alternating current (AC) in the late 1880s and 1890s, and have stayed that way ever since. Alternating current travels like a wave: the energy shimmies back and forth through a conducting medium. As the distances of transmission increase, it takes more and more energy to push this wave through. Inherently, the more energy you put in, the more that is lost. Direct current on the other hand is a steady flow of energy, there is no oscillation. Therefore, over transcontinental distances, direct current power lines are much more efficient. The power lines are cheaper to build, because a smaller wire can carry more power: reducing weight and cost. Whereas the transformers for AC are relatively cheap, the comparable thyristors for voltage conversion in DC are pricy; but these prices are justified by increased transmission efficiency, especially over long distances. Continue reading