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太陽能
太陽能在目前世界上能源發展速度位於第二，自1990年以來每年平均增長16%。根據《科學的美國人》雜誌報導，地球表面每年從太陽光中接收到的能量，是所有已知的煤、石油、天然氣、以及鈾的儲量總和之十倍左右。工業分析家們聲稱，只要利用地球上1%的沙漠來獲取太陽能，可提供的電力比目前全世界用化石燃料所生產電力的總和還要多。太陽能也有其局限性，但它特別適合應用於那些遠離高壓輸電網的地區；在這樣的地方，全世界的3億3千萬個家庭（20億人口）中，大多數還生活在沒有電的世界中。然而，PV（譯註）裝置的產量遠遠落後於需求（姑且不提購買它們所需的費用）。根據非洲替代能源開發公司馬克•漢金斯的計算，要對全世界每一戶尚未有電的家庭供應20瓦的電（足夠兩隻燈泡和一台收音機一晚上使用4個小時），就得生產6,600兆瓦的電力 - 即目前年發電量的66倍。（譯註： PV = Photovoltaic Cell 光電電池。）
要轉換太陽的能量有好多種方法，兩種最常用的方法是採用光電電池（PV）和太陽能轉換熱能。太陽能轉換熱能用作為大型能源有較大潛力，然而光電電池則非常適合為遠離輸電線路的建築物提供電力。
光電電池的作用是將太陽的光能轉換成直電流；光電電池是靜態的裝置，它也不需使用燃料。在過去25年中，隨著光電電池用途越來越廣泛，其價格已經下跌100多倍。新技術已經使太陽能電池的製造成本不斷地降低。科學家們相信，在未來十年內，這些技術會使太陽電池的成本從1998年的4,000美元/千瓦，降低到1,000美元/千瓦，進而使太陽能電池在全世界許多地方成為一種競爭力很強的電力來源。
光電電池具有很多優點：
▲沒有能源成本，只有設備成本。
▲它很清潔，沒有噪音，幾乎不需要維護。
▲只要有人力資源，就可以培訓當地人員安裝並維修光電電池系統，並能減少對政府提供輸電線路的依賴。肯亞的光電電池工業非常繁榮，目前由太陽能系統供電的家庭要多於從國家供電網路獲得電力的家庭，而且當地人也已經受到安裝並維修太陽能設備方面的培訓。
根據「看守世界協會」的統計，現在全世界約有50萬個家庭正在使用光電電池自行發電；對於尚未享用電力的20多億人口來說，太陽能恐怕是獲得能量最省錢的方式。
波札那、納米比亞、南非和該地區（非洲南部）的其他一些國家都設立了優惠專案，鼓勵鄉村地區安裝低成本的光電電池系統。例如，在納米比亞，家庭太陽能系統專案已經培訓了100多名技術人員，負責安裝與維修太陽能系統。在波札那，「國家農村電氣化之光電電池專案」的目標是：「提高光電電池照明系統到再生能源的地位，增強當地公司的聲譽，幫助農村人民為這些系統找到融資機會。」該專案始於1997年，為想要安裝光電電池專案系統的偏遠鄉村提供優惠貸款；它通過要求村民們建立起有關當事人的團體，以保持住低的付費水平。波札那首都哈伯羅內，通過安裝3000台太陽能熱水器而減少了5%的用電需求。南非政府已經保證，要讓250多萬戶家庭在新世紀來到之前用上太陽能發的電。
【文章連載】
■新能源的產生 (上)
版權歸屬 國際河網IRN，環境資訊協會（陶俊、李傑 譯，吳國玢、李瑞玉 審校）
中英對照全文：http://e-info.org.tw/issue/water/2001/is-water-irn01102901.htm |
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Solar
Solar power is now the world's second fastest-growing energy source, increasing on average 16 percent per year since 1990. Each year the earth's surface receives about 10 times as much energy from sunlight as is contained in all the known reserves of coal, oil, natural gas and uranium combined, according to Scientific American magazine. Using just 1 percent of the earth's deserts to produce solar energy would provide more energy than is currently being produced worldwide by fossil fuels, say industry analysts. While solar has its limitations, it is especially appropriate for off-grid applications, where most of the world's 330 million families (2 billion people) without power live. Still, production of PV units (not to mention the money to purchase them) lags behind need. Mark Hankins of Energy Alternatives Africa (see Contacts) calculates that to supply each of the world's off-grid families with 20 watts of power (enough for a couple of lights and a radio for 4 hours a night) would require 6,600 megawatts of power - or 66 times the current annual production.
There are a number of ways to convert energy from the sun. The two most common are photovoltaic cells (PV), and solar thermal. Solar thermal has more potential as a large-scale energy source, while PVs are excellent for powering buildings off the energy grid.
PVs work by converting the sun's light energy into direct-current electricity. PVs have no moving parts and use no fuel. The price for PVs have dropped more than 100 fold in the past 25 years, as their use has grown. Already, new technologies are lowering the cost of manufacturing solar cells. Scientists believe that such technologies can cut solar cell costs from $4,000 per ' kilowatt in 1998 to $1,000 in the next decade, which would make them a competitive source of electricity in many parts of the world.
PVs have many advantages:
▲There is no cost for the energy, only the equipment.
▲It is clean, silent, and requires very little maintenance.
▲Local people can be trained to install and repair PV systems, providing a source of employment as well as reducing reliance on the government for grid electricity. Kenya has a thriving PV industry, and more households now get their electricity from solar systems than from the national grid and local people are trained in installing and maintaining solar units.
According to the WorldWatch Institute, approximately 500,000 homes around the world are now generating their own power with PVs. For the more than 2 billion people not connected to a grid, solar power could be the most affordable way to get energy.
Botswana, Namibia, South Africa and other countries in the region have incentive programmes to install PV systems in rural areas at low cost. In Namibia, for example, the Solar Home System project has trained more than 100 technicians who install and maintain solar systems. And in Botswana, the National PV Rural Electrification Programme's goals are "to raise the standing of PV lighting systems as a renewable energy source, enhance the reputation of the local PV companies, and to assist rural people in finding financing for these systems." The programme, begun in 1997, offers loans at good terms for rural villages wishing to have PV systems installed; it keeps costs down by requiring villagers to form groups of interested parties. Botswana's capital, Gaborone, has cut electricity demand by 5 percent by installing 3,000 solar water heaters. The government of South Africa has pledged to electrify more than 2.5 million households with solar by the turn of the century.
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