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June 4, 2008

House debating renewable energy

The Rhode Island House of Representatives this afternoon is debating a major energy bill that supporters say will help move the state away from its dependence on electricity generated by fossil fuels.

The Senate passed the same bill yesterday.

If passed, the bill would require National Grid to enter into “commercially reasonable” long-term contracts with renewable-energy developers to purchase their electricity. That requirement would give assurance to prospective developers that there would be a buyer for the electricity produced by the project. Such assurance, the developers have said, is needed to borrow money to build renewable energy projects.

The utility company would have to enter into contracts that total 90 megawatts of average generating capacity. That total is arrived at after accounting for the fact that the wind turbines will only produce electricity some of the time (when the wind blows faster than a certain speed) and the fact that the solar panels won't produce much power when it's cloudy.

Here is what that 90 megawatts really means and how it relates to a typical household's energy consumption:

First, one needs to figure out how much power that is, expressed in the number of kilowatt-hours. 90 megawatts x 8,760 hours in a year = 788,400 megawatt-hours, or 788.4 million kilowatt-hours over the course of one year.

National Grid supplies Rhode Island with about 6.6 billion kilowatt-hours of electricity a year.

So that means that 788,400 megawatt-hours of renewable energy would represent about 12 percent of all electricity consumed in the state.

How many homes would that power? If the average home uses 500 kilowatt-hours per month, that’s 6,000 kwh per year. 788,400,000 kwh / 6,000 kwh = 131,400 homes.

Ronald Gerwatowksi, vice president of distribution regulatory services for National Grid, confirmed the calculations but cautioned that other variables should be taken into account.

First, he said, it's likely that some of the renewable energy projects-- with which National Grid contracts -- may not be built, "due to siting and other project development difficulties."

"Thus, signing contracts to that level is not likely to result in as many megawatt-hours as you assume in the analysis," Gerwatowksi said. "It will be something less."

Secondly, he said the legislation relies on rules set by ISO New England that estimate the actual amount of electricity a renewable energy project would produce. He said those rules may be overly optimistic.

"For that reason, as well, it is hard to be certain about how many megawatt-hours actually will be produced," he said.

-- Journal staff writer Timothy C. Barmann

Posted by Tim Barmann  at 5:45 PM | Permalink

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