In 2008, he signed the state's renewable portfolio standard, calling for 25% of the state's energy to be produced by renewables by 2025.

Thirteen states already have renewable energy goals, called portfolio standards, but environmentalists said that New York's would be among the most aggressive of all.

New York has a renewable portfolio standard of 30% from renewable sources by 2015.

This portfolio standard would reduce our dependence on traditional polluting sources of electricity.

The use of hydroelectric technology is promoted by Renewable portfolio standards and various financial incentives.

Hawaii has a renewable portfolio standard of 40% renewable energy by 2030.

It has relied on support mechanisms such as feed-in tariffs, renewable portfolio standards, loan guarantees and tax credits.

Wisconsin's renewable portfolio standard requires 10% renewable sources for electricity by 2015.

In addition, 13 states have established a requirement called a renewable portfolio standard.

More than 20 states have so-called renewable portfolio standards, which mandate that utilities derive a fixed percentage of their power from renewable sources.