"Alternative" energy is officially not so alternative anymore. Last year, for the first time ever, spending on projects to generate electricity from renewable sources eclipsed the amount spent to build conventional fossil fuel plants.

In 2010, renewable projects drew $187 billion in investment, 19 percent more than the $157 billion spent to build or augment conventional generating plants, fuelled by natural gas, oil and coal, according to analysis released by Bloomberg New Energy Finance for the Durban climate talks. As the clean energy sector comes of age it must now reckon with the challenges of more mature industries. Namely, managing the risk posed by larger, more complex projects. According to "Managing the Risk in Renewable Energy," a report released this week by the Economist Intelligence Unit and Swiss Re, minimizing financial risk is one of the most "acute" challenges facing the sector in the near term.

The renewable energy sector will face an even more uncertain future if it fails to manage the growing risks associated with larger, more complex projects, EIU found. The study was based on survey of 284 senior-level renewable energy executives.

The survey found that renewables have moved to center stage. Power companies increasingly view renewable energy as central to their business strategies, and are developing larger and more complex renewable energy projects. Billion dollar projects, once rare, have become regular.

Worry is rising among renewable energy investors that some of the other 100 or so governments supporting clean energy will cut public subsidies as part of austerity measures, the report found. Fiscal crisis in Europe and economic malaise in the U.S. suggest public support for renewable energy is more likely to shrink than grow in the near term. For example, solar feed-in tariffs are being slashed across Europe: lowered by 15 percent in Germany and up to 70 percent in the U.K.

As public funds dry up, the appetite for renewables remains strong, siginaling a shift to more private funding. "Risk management measures such as insurance will be key to encourage further private sector investment," said Agostino Galvagni, Chief Executive Officer Swiss Re Corporate Solutions in a statement. "Additional investments into renewable energy are needed to achieve the transition to a low-carbon economy," he added.

A major issue in renewable energy projects is their high up front costs. Projects are typically capital-intensive and highly leveraged, with up to up to three quarters financed through debt. As companies seek to scale up investments, overcoming financial risks is one of the biggest challenges, according to 76 percent of the survey respondents.

Among plant investors, owners and operators surveyed, other significant concerns included political and regulatory risk (62 percent) while weather-related volume risk comes in third for wind power producers (66 percent). These risks increase further as projects grow in scale and complexity.

The report revealed that while companies are sophisticated in using insurance elsewhere in their businesses, the dearth of risk-management tools in the renewables space has limited their use. About two-thirds of respondents already use insurance to transfer risks. But only half of respondents said they are currently transferring risk successfully, for example through insurance to hedge against the risk of weather-related reductions in output of a solar park or wind farm. Instead, because of the limited availability of suitable risk-transfer mechanism, many retain the risks related to renewable energy assets on their balance sheets due to.