n. Technology that is itself environmentally friendly or that helps reduce environmental problems; the business sector that produces such technology.
Also Seen As
Venture capital investment in clean technology businesses rose sharply in 2007, reflecting political and consumer support for a greener economy. …

Clean applications — which include renewable power, energy efficiency and recycling — are seen as particularly promising areas.

"An awareness of cleantech has exploded across the world, with the US investing in biofuel, China in solar power and Europe declining to be left behind," says Ed Hugo, an analyst at Library House.
—Jonathan Guthrie, “Investment boost for 'clean' start-ups,” Financial Times, January 15, 2008
Environmental problems such as climate change are "rewriting the rules for business" and sparking economic investment to the tune of billions of pounds, claims a new report. According to Worldwatch Institute's State of the World 2008 study, money is pouring into areas such as renewable energy, green technology and carbon markets as businesses recognise the opportunities they present. …

So-called "cleantech" — such as technology which improves energy efficiency or reduces pollution — was the third largest recipient of venture capital, behind the internet and biotechnology.
—Sion Barry, “Billions of pounds pouring into green technologies worldwide,” The Western Mail, January 12, 2008
1990 (earliest)
The present urgent environmental problems facing the ESCAP (U.N. Economic and Social Commission for Asia and the Pacific) region need greater regional cooperation, a senior U.N. official said here today. …

An exhibition, named "Cleantech (clean technology) 1990", was also opened to public today. On display at the exhibition are photos of environmental prevention and protection, air, water and waste treatment equipment provided by some of the ESCAP members.
—“Environmental problems need greater regional cooperation: U.N. official,” Xinhua General News Service, October 10, 1990
Clean technology, or cleantech, is also known as environmental technology, greentech and other catchy names. It basically refers to technologies that enable more valuable use of natural resources and greatly reduced ecological impact.
—Matthew Sheahan, “VCs Show Off Their Green Thumbs,” Venture Capital Journal, May 01, 2004