Cleantech—short for clean technology—is a word used in finance to describe a variety of firms and technologies that strive to promote environmental sustainability. The term’s meaning has evolved through time, with some users using it interchangeably with phrases like “green technology” to refer to renewable energy sources, innovative recycling processes, and other ecologically beneficial activities.
In other situations, the phrase refers to techniques for decreasing the negative environmental effect of otherwise traditional technologies like coal or natural gas. Terms such as “clean coal” or “clean energy” is often used in this context, however many environmentalists doubt their validity.