共用题干 Thirst for Oil
Worldwide every day,we devour the energy equivalent of about 200 million barrels of oil. Most of the energy on Earth comes from the Sun. In fact enough energy from the Sun hits the planet"s surface each minute to cover our needs for an entire year,we just need to find an efficient way to use it. So far the energy in oil has been cheaper and easier to get at. But as supplies dwindle,this will change,and we will need to cure our addiction to oil.
Burning wood satisfied most energy needs until the steam-driven industrial revolution,when energy-dense coal became the fuel of choice. Coal is still used,mostly in power sta-tions,to cover one quarter of our energy needs,but its use has been declining since we star-ted pumping up oil. Coal is the least efficient,unhealthiest and most environmentally dama-ging fossil fuel,but could make a comeback,as supplies are still plentiful:its reserves are five times larger than oil"s.
Today petroleum,a mineral oil obtained from below the surface of the Earth and used to produce petrol,diesel oil and various other chemical substances,provides around 40% of the world"s energy needs,mostly fuelling automobiles. The US consumes a quarter of all oil,and generates a similar proportion of greenhouse gas emissions.
The majority of oil comes from the Middle East,which has half of known reserves. But other significant sources include Russia,North America,Norway,Venezuela and the North Sea. Alaska"s Arctic National Wildlife Refuge could be a major new US source,to reduce reliance on foreign imports.
Most experts predict we will exhaust easily accessible reserves within 50 years,though opinions and estimates vary. We could fast reach an energy crisis in the next few decades, when demand exceeds supply. As conventional reserves become more difficult to access,oth-ers such as oil shales and tar sands may be used instead. Petrol could also be obtained from coal.
Since we started using fossil fuels,we have released 400 billion tonnes of carbon,and burning the entire reserves could eventually raise world temperatures by 13℃ .Among other horrors,this would result in the destruction of all rainforests and the melting of all
Arctic ice. What do experts say about the earth"s fuel reserves?