When Federal Aviation Administration officials grounded Boeing's fleet of 787 Dreamliner commercial jets last week due to unexplained battery fires, one of President Obama's favorite green energy technologies got another black eye.

Technologists and safety experts had long warned of problems with the lithium ion battery when in 2009 the president began betting billions of tax dollars that it should be the green power of choice for cars, trucks, and even aircraft.

Just three years before that, a UPS cargo plane made an emergency landing when a shipment of lithium ion batteries it was carrying caught fire. The plane landed safely but was destroyed by the ensuing conflagration.

Small lithium ion batteries are widely used in consumer electronics, but powering vehicles like a car or an aircraft is a much greater challenge. The 787, for example, has to generate 1.5 megawatts of electrical power, enough to light up several hundred homes.

Boeing and the FAA said the 787 will not fly again until the battery fires are explained and fixed. There have been a total of four reported fires, including one during 2010 pre-delivery flight, according to Scientific American.

The problem, according to the MIT Technology Review, is that "because the electrolyte materials used are flammable, no lithium-ion batteries are completely safe."

And last April, the National Fire Protection Association warned that "as lithium-ion battery use increases, so do the concerns related to the fire-safety hazards of these devices."

Some experts believe the batteries have been oversold to the public.

"Lithium ion batteries just won't do the trick in the kind of mass vehicle applications that the environmental community is pushing for," said Jon Entine, founder of ESG Media Metrics, a Cincinnati-based environmental consulting firm.

"It's kind of glib environmentalism or kind of enviro-romanticism," said Entine, who is also a senior fellow at George Mason University's Center for Health and Risk.

Lithium ion batteries are a serious technology but "not the solution and to suggest it's the silver bullet when it has as many costs and benefits is na?ve," he said.

The largest known reserves of lithium are in Latin America and China.

Before the Dreamliner's troubles, a Chevrolet Volt caught fire during its crash tests by the National Highway Traffic Safety Administration in May 2011. The agency gave the Volt a clean bill of health after an investigation.

Then last year, electric truck manufacturer Smith Electric Vehicles warned potential investors that the lithium ion batteries "on rare occasions have been observed to catch fire or vent smoke and flames" in the firm's prototype military trucks.

Even in the smaller consumer electronics applications, lithium ion battery fires were reported in Apple and Dell laptop computers in 2005 and 2006.

Despite these incidents, Obama has poured federal subsidies on the lithium ion battery industry with mixed results. The first grant was for $249 million under the Obama economic stimulus program in December 2009 to A123 Systems, a lithium ion battery manufacturer.

But A123 Systems filed for bankruptcy last October and has since been bought by a Chinese company.

Obama toured the LG Chen lithium ion battery plant in Holland, Michigan in August 2011. The South Korean company got $151 million in federal subsidies, but it has yet to produce a single battery and furloughed its workers last fall.

Ener1, an Indianapolis-based lithium ion battery maker, received $118.5 million in federal money in 2009, but filed for bankruptcy last year.

The president awarded $529 million to electric car company Fisker, which utilized lithium ion batteries supplied by A123. At least two battery fires have been reported in Fisker vehicles, all of which have been recalled.

Obama issued a $465 million loan guarantee to Tesla Motors. The lithium ion battery in a Tesla reportedly burst into flames last year after not being recharged for a long period of time.

Several high-powered K Street lobbyists are pushing battery powered vehicles, including Tony Podesta, whose brother was President Clinton's chief of staff. Podesta was tapped in 2010 to represent the Electrification Coalition.

The coalition has spent $400,000 lobbying, according to congressional lobbying records. Its membership includes the former chairman of bankrupt Ener1. The Electric Drive Train Association, have spent $840,000 lobbying. Its members include A123, Tesla Motors and Smith Electric.

Richard Pollock is a member of The Washington Examiner's Watchdog reporting team.