tailieunhanh - Energy A Beginner’s Guide Part 10

Năng lượng tái tạo hay năng lượng tái sinh là năng lượng từ những nguồn liên tục mà theo chuẩn mực của con người là vô hạn. Nguyên tắc cơ bản của việc sử dụng năng lượng tái sinh là tách một phần năng lượng từ các quy trình diễn biến liên tục trong môi trường và đưa vào trong các sử dụng kỹ thuật. | 170 energy a beginner s guide surpasses actual electricity demand the sole provider of the base load supply. Other factors that complicate large-scale reliance on wind-driven turbines range from the sudden substantial 10-20 loss of power due to the soiling of leading blade edges by swarms of summer insects to the damage that could be inflicted on towers and blades by hurricane- and tornado-strength winds. Environmental concerns range from the well-documented risks to migrating birds to esthetic objections both to turbines massed in large onshore wind farms and the size of the largest machines nearly twice as high as the Statue of Liberty . As with any major engineered system it is far too early to appraise the overall reliability of the technique. We have to accumulate operating experience with a very large number of units to be able accurately to assess the long-term availability and reliability of wind turbines how will offshore wind farms fare in hurricanes how will the machines be affected by heavy icing or to what extent will the smooth blades surfaces be pitted by abrasive airborne particulate matter Compared to wind-powered electricity generation with recent worldwide annual increments of the order of 5-8 GW and aggregate installed capacity in 2005 of over 50 GW photovoltaics PV is still a minor affair its worldwide capacity was below 3 GW in 2005 with just three countries Japan Germany and the US accounting for more than eighty per cent of the total. Moreover the power ratings of PV units are not directly comparable with other modes of electricity generation because they are expressed in peak watts measured under high irradiance 1 000 W m2 the equivalent of mid-day clear-sky insolation rather as an average performance. Three fundamental reasons make the PV conversion of solar radiation into electricity the most appealing of all renewable sources the unparalleled magnitude of the resource its relatively high power density and the inherent advantages of the .