单选题
Energy
In industrialized nations, people are using more and more energy all the time so that its demand is ever increasing. Practically everything we do, from talking on the phone to driving to work and heating up our lunch, it all requires energy. Most of this energy comes from fossil fuels, but the problem is that fuels like coal, oil and natural gas are non-renewable, and burning fossil fuels also releases chemicals into the air that damage the environment and pose a serious risk to public health. Fossil fuels are found in deposits beneath the earth; they are the result of decayed plants and animals buried in rock that over time have become fossilized. Time and pressure gradually turned those fossilized organic deposits into coal, oil and natural gas.
The energy demand and usage have risen sharply over the last thirty years and are only set to further increase. Emissions released due to the burning of fossil fuels are harmful to the environment, and the only way to reduce emissions is to switch to low carbon alternatives.
Alternative renewable energy sources include wind and solar power both of which are abundant non-polluting and sustainable energy resources. People are increasingly turning to such renewable sources although they still very, much rely on fossil fuels. Oil, gas and coal are used to generate electricity in power stations. Gas can be extracted directly from wet natural gas or can be obtained as a by-product of the petroleum refining process.
As well, the amount of energy people use for their everyday lives has increased dramatically, but the amount of energy used by industry has decreased because of fewer energy intensive industries and better energy efficiency. The main environmental impact of burning fossil fuels comes from the emission of greenhouse gases. Scientists agree that greenhouse gases are the major source of climate change, which is otherwise known as global warming. Oil spillages from oil refineries and drilling sites are also a major cause of environmental pollution. The damage caused by harvesting and burning fossil fuels can be seen in the pollution of water flowing through coal mines. This in turn contaminates other water sources. Methane gas leaking from pipe lines and coal mines further contributes to the greenhouse effect. Exhaust gases from vehicles emit substances such as nitrogen dioxide and greatly affect public health, especially those suffering from asthma. In addition to carbon dioxide, burning fossil fuels also releases other gases, such as sulphur dioxide, into the atmosphere, increasing the greenhouse effect and causing acid rain, thus heavily polluting the air in those urban areas in which their concentrations are normally highest.
World total fossil energy demand is expected to increase even faster than today in the not fat distant future because of accelerated economic development by the newly emerging industrial nations, such as China and India.
It will not be easy to change the way nations supply and use energy but what is certain is that changing to renewable energy sources will greatly reduce greenhouse gas emissions. Moreover, the efficient management of renewable sources and the radical reduction of pollution cannot be achieved without the formulation of and commitment to long term plans.
Glossary
emission:
substances and especially pollutants discharged into the air
alternative:
something which can be chosen instead
fossil fuel:
fuel consisting of the remains of organisms preserved in rocks in the earth"s crust with high carbon and hydrogen content
exhaust:
the release of vaporous waste material, as from an engine
sustainability:
ability to keep in existence