State and local bond markets, which have long financed the construction of roads, bridges, hospitals and other infrastructure projects across country, offer a viable but vastly underused funding source for clean energy development, according to a paper released Friday by the Brookings Institution Metropolitan Policy Program. Clean energy leaders are beginning to experiment with bond financing because it can reduce both the cost of capital and the financial risk. For example, late last year the state of New York raised $24.3 million in revenue bonds that will be used to finance loans for energy efficiency improvements. Hawaii plans to issue green infrastructure bonds to provide low-cost financing for clean energy generation projects and energy efficiency building upgrades. And since 2009, Morris County, N.J., has financed solar installations in public facilities partly with low-interest bonds. To read last week's Business Record cover story about solar energy's outlook in Iowa, click here.