Google said Tuesday it is refining PowerMeter software that tells residents which devices in their homes are electricity hogs and which are being frugal with energy.

The announcement comes as the California Internet titan urges increased investment in a nationwide "smart grid" electricity network to better track and manage power consumption.

PowerMeter software being tested by Google workers receives information from "smart" electric meters and devices such as appliances and then sends to users' computers detailed reports about how the power is being divvied up.

One Google engineer said he saved 3,000 dollars last year after feedback provided by PowerMeter prompted energy-trimming changes to incandescent light bulbs, a swimming pool filter and two old refrigerators.

A Google program manager said PowerMeter tipped her off to a stuck dial on a toaster oven that could have started a fire in the kitchen of her apartment.

"Imagine how hard it would be to stick to a budget in a store with no prices," Google engineering team member Ed Lu wrote in a posting at the company's website.

"Well, that's pretty much how we buy electricity today. But, in a world where everyone had a detailed understanding of their home energy use, we could find all sorts of ways to save energy and lower electricity bills."

Google cited studies indicating that access to details about energy consumption results in people trimming five to 10 percent from monthly electric bills.

"We believe consumers have a right to detailed information about their home electricity use," Lu wrote.

"We're tackling the challenge on several fronts, from policy advocacy to developing consumer tools, and even investing in smart grid companies."

In a letter written Monday to the California Public Utilities Commission, Google called for policies that result in people getting real-time data regarding their electricity use.

"This will allow consumers to have greater understanding of, and control over, their electricity usage, and will reduce energy demand and the need to build new generation," Google maintains in the letter.

"Electricity demand reductions will in turn produce savings for consumers and utilities and reduce greenhouse gas emissions."

A smart grid imbued with computer capabilities would bring the US electricity grid into the digital age and better accommodate power generated by independent renewable sources such as solar panels.

There are approximately 40 million smart meters in use worldwide. Smart meters have computer chips and can use the Internet to relay information about electricity use to utility companies or consumers as desired.

The current electric grid requires utility company workers to periodically read consumers' meters to calculate overall consumption.