Clean technology companies welcomed nearly USD2.4 billion for the sector in the Obama administration's proposed budget released on Monday, but some industry watchers said it wasn't enough for major changes in the emerging market or for long-term growth.

US President Barack Obama's new budget gave a shot in the arm for energy efficiency and renewable energy programs, and was a huge increase from USD113 million in the previous budget. It also included various climate measures and an additional USD36 billion in loan guarantees for nuclear energy.

The WilderHill Clean Energy Index, which includes solar power companies, battery maker A123 Systems and other clean energy companies, closed up nearly 3 percent on Monday.

However, J.P. Morgan analyst Christopher Blansett said that measures in the budget such as USD500 million in credit subsidies for energy efficiency and renewable energy projects do not account for much in the "big picture perspective."

"I don't think people realize the scope of how much money really needs to be spent to make big structural changes in either our energy consumption, use or production," Blansett said.

The emerging renewables and green technology industry -- which struggled in 2009 amid the credit crisis and a dearth of available financing for new projects -- still leans heavily on government incentives.

A bill to tackle climate change is stalled in the Senate amid opposition from lawmakers from coal-and oil-producing states, and many companies hope the United States will adopt a renewable electricity standard requiring more power from resources like wind and solar.

Blansett estimated that it will cost between USD158 billion to USD445 billion if the United States adopts a national electricity standard requiring 15 percent of all electricity in the country to come from renewable resources by 2020.

Privately held solar developer Recurrent Energy's Chief Executive Arno Harris said that in the long term the US government needs to provide direct support to renewables -- such as a renewable electricity standard -- and move away from tax-based incentives.

"We are seriously concerned there aren't enough investors with tax appetite to basically provide the capital for the build-out of resources that we anticipate," Harris said.