More of the electricity used by Rhode Islanders would be generated by the sun, the wind and other environment-friendly sources under a new bill introduced in the General Assembly.

The measure would gradually step up the amount of "green power" supplied to the state until it reaches 20 percent of all electricity consumed at the end of 2020.

The legislation is one of two key energy-related bills designed to lower the use of fossil fuels, such as natural gas and oil, as well as reduce overall energy consumption in the state.

The "clean energy bill" would require that at least 3 percent of retail electricity sales in the state come from renewable resources by the end of 2006. That requirement would increase by 1 percent each year until 2016, and 1.5 percent from 2017 through 2020.

The power could be generated by solar radiation, the wind, movement of the latent heat of the oceans, the heat of the earth, small hydro-electric facilities, biomass facilities and fuel cells.

Right now, about 2 percent of the state's electricity supply comes from renewable resources, according to Kate Strouse Canada, an advocate for the Rhode Island Public Interest Research Group, which supports the bill. Most of that is electricity produced from landfill gas, she said.

The reason the percentage is so low is primarily cost since it is often more expensive to generate electricity from alternative sources.

Those who support the bill acknowledge it could result in higher utility costs. Some studies have suggested that a clean energy bill such as the one being proposed in Rhode Island might add $2 a month in utility costs for a residential customer in 2020.

But supporters say renewable energy costs are coming down and becoming much more competitive with power generated from traditional fuels. Wind power, for example, can be cheaper, depending on the size and location of the turbine installation.

Canada said there are other costs of using fossil and nuclear fuels that should be considered. Those include health problems caused by air pollution, such as asthma attacks, and the security costs associated with protecting nuclear power plants from terrorist attacks.

Another benefit of increasing green energy, supporters say, is the stabilization of energy prices. Canada compared investing more in renewable energy to diversifying a stock portfolio.

The more variety of securities one owns, the less likely the overall portfolio will be affected by fluctuations in the market. By making "green power" a bigger part of the mix, it will help dampen the effects of price spikes associated with rising fuel prices, she said.

Shifting towards more renewable energy can also be a boost to the state's economy, supporters say. Specifically, they say, it can help companies that make devices related to renewable energy, such as TPI Composites of Warren, which makes blades for wind turbines.

A similar bill was passed in the House of Representatives last year, but died in the Senate. Related legislation has been passed in 13 states, Canada said, including Connecticut, Massachusetts and Maine.

Another energy-related bill introduced in the House would phase out the sale of products that do not use electricity efficiently. Among the worst offenders are cable television boxes, halogen lamps and ceiling fans.

The bill, which is also supported by RIPIRG, would require that certain products sold in the state after 2006 meet minimum-efficiency standards.

A similar bill was passed recently in Maryland, and a veto by the governor was overridden by the legislature.

Requiring the sale of more energy-efficient products comes at a price: they are typically more expensive than their power-hungry counterparts. The bill could push up prices for some items.

However, supporters of the bill say that the amount of money saved over time by using energy-efficient devices will make up for the initial higher cost of the products.

The particular products that are targeted in the bill are those that will have a relatively short pay-back period, said Canada of RIPIRG.

The total savings in electricity costs over the next 15 years for residential customers and businesses in the state would total about $280 million, Canada said.

Not everyone supports the bill. Cable television companies, which buy cable boxes and lease them to customers, have opposed similar measures in other states.

The New England Cable Television Association, which represents major cable companies in the region, including Cox Communciations, said last year that such legislation would make it harder and more expensive for cable companies to provide the kind of interactive services that customers want.

The association said it would prefer a federal approach to energy efficiency standards for cable boxes, rather than each state enacting its own.