When it comes to clean energy, last year was a mixed bag, as the Clean Energy Trends 2013 report by Clean Edge points out. The report makes it clear that 2012 "proved to be an unsettling and difficult year for clean energy." The reasons include "high-profile bankruptcies and layoffs." However, even in the midst of all of that, the clean energy sector saw growth, particularly in solar, wind and biofuels.
Renewables accounted for 49 percent of added capacity in the U.S. in 2012, while coal was only 17 percent, with no new nuclear added capacity. The combined global revenue for solar photovoltaic (PV), wind power, and biofuels grew year-to-year, although only a bit, from $246.1 billion in 2011 to $248.7 in 2012. "This marginal growth doesn’t reflect the industry’s true expansion," the report states.
2012 was a year of extreme uncertainty for clean energy markets, as venture investors pulled back and high-profile bankruptcies became a partisan wedge in the presidential election, all while climate disruptions brought clean tech back into the limelight," said Ron Pernick, Clean Edge co-founder and managing director. "But a key lesson emerged from last year – the focus for investors and industry for the near- to mid-term will be on deployment.
Here is an overview of the report's findings for biofuels, wind, solar, geothermal, microhybrid, and venture capital (VC) investment.
Biofuels
The global production and wholesale pricing of ethanol and biodiesel was $95.2 billion in 2012, an increase from $83.0 billion in 2011. It is projected to grow to $177.7 billion by 2022.Wind
Global wind capacity grew by 44.7 gigawatts (GW) in 2012, with over 13 GW added in China and the U.S., and 12.4 GW in Europe. Wind represented almost half of all new U.S. generation capacity added in 2012, 41 percent of the total, and outpaced natural gas's 33 percent share. Nine U.S. states generated over eight percent of in-state electricity from wind by the end of 2011.Solar
Solar PV in the U.S. actually decreased from $91.6 billion in 2011 to $79.7 in 2012 because PV prices declined. However, global installations increased to 30.9 GW in 2012, an increase from 29.6 GW in 2011. Solar PV revenues are expected to increase to $123.6 billion by 2022.Geothermal
The U.S. geothermal market is the world's largest, with over a quarter of the worldwide total of installed cumulative capacity. In 2012, the U.S. added 77 megawatts (MW) of capacity, up from a combined total of 25 MW for 2010 and 2011.Micro-hybrid
Also called stop-start, it's described as the technology that stops a vehicle's motor during idling with a battery and not gas. Over 40 percent of new cars sold in Europe and Japan have stop-start technology. The report predicts that stop-start technology will "come to the U.S. in a big way," and have a big impact on fuel efficiency. All hybrids in the U.S. have stop-start technology, but the first non-hybrid stop start systems were introduced into the U.S. market last year for BMW, Mercedes and Porsche models.Lux Research predicts that over eight million vehicles, not including hybrids, will have stop-start technology in North America by 2017, about four times the current number of hybrids on the road in the U.S. Johnson Controls forecasts that over 35 million vehicles with stop-start technology will be produced worldwide by 2015.
Venture capital
U.S.-based VC investments in clean technologies last year totaled $5.0 billion, down from $6.6 billion in 2011. It marked the first time in three years that VC investments decreased. Worldwide VC investments in clean tech also decreased.Image credit: Flickr user, Living Off Grid

Gina-Marie is a freelance writer and journalist armed with a degree in journalism, and a passion for social justice, including the environment and sustainability. She writes for various websites, and has made the 75+ Environmentalists to Follow list by Mashable.com.