recycling

Geothermal energy is derived from the natural heat present below the surface of the Earth. Cool water is pumped down where it is heated up in large underground reservoirs before being pumped back to the surface.

A glass recycling mountain in Stuttgart, Germany. Overall, the UK recycles much less than other European countries. Bottle banks appeared for the first time in the UK in 1977, and by 2000 there were over 20,000 bottle bank sites (1 for every 2,800 people). The average glass bottle contains over 25% recycled glass. Green-glass bottles manufactured in the UK contain at least 60%, and sometimes as much as 90%, recycled glass.

A collection of green glass bottles due to be recycled. In the last quarter of the 20th century, the benefits of reprocessing discarded paper, glass, tin and aluminium containers, and some plastics, became clear. But some developed countries such as the USA recycle far less waste than other countries, and conservationists must convince packaging producers that expensive reprocessing is worthwhile.

Processing of industrial and household waste (such as paper, glass, and some metals and plastics) so that the materials can be reused. This saves expenditure on scarce raw materials, slows down the depletion of non-renewable resources, and helps to reduce pollution. Aluminium is frequently recycled because of its value and special properties that allow it to be melted down and re-pressed without loss of quality, unlike paper and glass, which deteriorate when recycled.

The USA recycles only around 25% of its waste (1998), compared with around 33% in Japan. However, all US states encourage or require local recycling programmes to be set up. It was estimated in 1992 that 4,000 cities collected waste from 71 million people for recycling. Most of these programmes were set up 1989–92. Around 33% of newspapers, 22% of office paper, 64% of aluminium cans, 3% of plastic containers, and 20% of all glass bottles and jars were recycled.