Development of renewable energy sources has taken big jumps throughout the world, according to a 2007 global status report from The Worldwatch Institute, an environmental research group.

Mandates for solar hot water in new construction represent a strong trend in countries around the world, the group says. Rooftop solar heat collectors provide hot water to nearly 50 million households worldwide. Existing solar hot water/heating capacity increased by 19 percent in 2006.

While we’re focusing on solar for this supplement, here’s a quick rundown of alternatives taken from a 2007 global status report:

• Renewable electricity generation capacity increased 50 percent in 2007 over 2004.
• Renewable energy generated as much electric power worldwide last year as one-quarter of the world’s nuclear power plants. That figure does not count large hydropower, but would be more than nuclear if it were counted.
• The largest component of renewable generation capacity is wind power, which grew 28 percent worldwide last year.
• The fastest-growing energy technology in the world is grid-connected solar photovoltaics with 50 percent annual increases in installed capacity in both 2006 and 2007.
• Production of biofuels (ethanol and biodiesel) exceeded an estimated 53 billion liters last year, up 43 percent from 2005.
• Renewable energy, especially small hydropower, biomass and solar PV, provides electricity, heat and water pumping for tens of millions of people in rural areas of developing countries. Twenty-five million households cook and light their homes with biogas and 2.5 million households use solar lighting systems.
• Developing countries as a group have more than 40 percent of existing renewable power capacity, more than 70 percent of existing solar hot water capacity and 45 percent of biofuels production.
• Policy targets for renewable energy exist in 66 countries, including all 27 European Union countries, as well as 29 U.S. states, including the District of Columbia, and nine Canadian provinces.