The United States is betting on that technological innovation will be able to reduce greenhouse gas emissions, the nation's secretary of energy said Monday in a speech, where he did not specify targets for the nation.

"We have invested 90 billion dollars over the last two years," said Steven Chu, a Nobel Prize winning scientist. "President Barack Obama feels that clean energy is about security: energy security, financial security and security for the planet."

Chu was speaking at a side event of the ongoing UN climate change conference held in Cancun, Mexico. The conference aims to find solutions to global climate change.

Chu said that the U.S. government had acted by publishing better appliance standards and creating fast-start funds for a series of innovative technology companies. He highlighted the case of one company that received four million dollars from the government for research and development, and had managed to obtain a further 25 million when the experiments proved fruitful.

Chu, who was awarded a Noble Prize for Physics in 1997, said that the U.S. was also focusing on supporting laboratories that will be centers of innovation in clean energy.

Chu did not accept any questions on U.S. climate change policy during his presentation.

Although having offered to cut some 17-percent greenhouse emissions from 2005 levels by 2020, the United States is the only developed country that refuses to ratify the Kyoto Protocol, the legally binding international treaty that commits most of the world's developed countries to making emission cuts.