Some US$6.8bn of venture capital had been invested in clean technology worldwide in 2013, research by market intelligence firm Cleantech Group suggests.
The amount reflects a 15pc decrease from 2012, when global venture capital investment in clean tech amounted to US$7.9bn, but an average growth rate of 14.5pc across all four quarters of the year hints at a strong industry this year.
The most profitable sector in 2013 has been energy efficiency, drawing US$1.3bn in venture capital investment, followed by transportation, with US$1.2bn, and then solar, which secured US$719m in funding. Biofuels and biochemicals, recycling and waste, advanced materials, agriculture and water also reaped nine-figure sums.
Venture capital investment in Europe and Israel's energy-efficiency sector increased 130pc in 2013, with a total of US$302m.
Transportation was the most attractive sector in Asia/Pacific last year, drawing US$299m in venture capital investment, while energy efficiency was most popular in North America, attracting a total of US$1bn.
Cleantech Group's research also shows that 1,007 deals had been completed in 2013.