Coal is one of the cheapest and dirtiest scalable methods of producing power. However, coal use was the driving force in the West's industrial revolution and the U.S. is still the leading producer and consumer of coal. For the past 50 years, however, the U.S. and other western countries have begun to move towards using more expensive forms of energy because of the long-term environmental costs thought to be linked with coal use. Now that China, India, South Africa and other nations are seekign to industrialize, they find competition for fuel reserves prohibitive and have turned to coal. The United Nations Environment Programme has suggested strong limitations on coal use, but such limits reduce the capacity of many nations to purchase the power needed for industry.