Công nghệ năng lượng mặt trời được mô tả rộng rãi như là hoặc năng lượng mặt trời thụ động hoặc năng lượng mặt trời hoạt động tùy thuộc vào cách chúng nắm bắt, chuyển đổi và phân phối năng lượng mặt trời. | 48 3 Limits to Renewability food will be a major issue. The crude figures for what will have to be provided are detailed below. In 2000 the average total worldwide power consumption by the human race population billion was 13 TW X 1013 W with from burning fossil fuels 5 6 . This is equivalent to X 1020 J per year although there is at least 10 uncertainty in the world s energy consumption. Not all of the world s economies track their energy consumption assiduously. Also the exact energy content of a barrel of oil or a ton of coal will obviously vary with quality. In 2007 given the rapid industrialisation of China and India on the back of abundant coal and increasing population 75 million year global consumption is probably nearer 15 TW and rising. By 2030 the population will have risen to billion. A increase in energy consumption 7 takes us to 20 TW in 2030. In the long term population is predicted to level off at billion. If we assume that energy usage per person does not fall sharply in the interim through the widespread adoption of energy conservation or through changes in lifestyles much less mobile populations then demand for electrical power will grow to at least 25 TW. The ball-park estimates of global energy potentially available from renewable resources when compared with the potential demands of a future energy hungry global economy clearly seems to suggest that more than enough renewable energy exists in earthly phenomena to meet mankind s needs. The big problem is given the short timescale of about 20 years to stop burning fossil fuels in order to bring greenhouse gas emissions down to 90-95 of 2005 levels how much of this resource can realistically be exploited using currently available technology and how close can we get to satisfying future demand from renewables This issue will be addressed in some detail in the ensuing sections. Hydro-power Where the Power Comes From From a purely electrical engineering .
