Chidambaram(TN),Jan 3: Ecologically sustainable supply and use of energy resources is one of the biggest challenge to which scientists in India must find answers for, Prime Minister Manmohan Singh said on Tuesday.

"The human race has been able to discover and invent new sources of energy that have benefited life on earth. But these also endanger life and our planet," the prime minister told the 94th Indian Science Congress in Chidambaram.

"We depend on our scientists and engineers to find ways and means of meeting our energy requirement in ecologically sustainable ways. This is a major development challenge facing us," he said in this temple town 225 km south of Chennai.

"India must find alternative sources of energy supply. We will need bio-fuels, solar energy, photo voltaic, nuclear and almost all sources, which do not burden the conventional sources of energy supply," he said.

At the same time, the prime minister said the assurance of energy security was a managerial and technological challenge that needed investments in billions of rupees but the return on this investment was far from adequate.

Speaking at the Annamalai University campus, Manmohan Singh said there was also an urgent need to upgrade the country's monsoon forecasting system, especially in rural areas, since this annual phenomenon remained unpredictable.

"The science of climate change is still nascent. This is why Indian scientists must engage in exploring the links between greenhouse gas emissions and climate change. You must also examine its impacts on our monsoons."

The prime minister said that Chidambaram town, home to the imposing Nataraja temple, was an appropriate venue for the congress since it was a reminder of what this year's theme was all about - "Planet Earth".

"We in India hold the five elements - wind, water, fire, earth and space in worshipful respect. In Chidambaram's vicinity there are temples to wind, water, fire and earth," he said.

"As one of the Pancha Bhoota Sthalams (temples dedicated to each of the five elements), where we worship space, Chidambaram is a fitting venue for your gathering this year."

Manmohan Singh also expressed concern over declining enrolment in schools and colleges in basic sciences and said scientific teaching ought to be made sufficiently interesting for young people.

"There is also widespread concern about the decline in the standards of our research work in universities and even in advanced research institutes. The university system needs upgrading," he said.

"Universities must once again become the hub of good quality science. We should institute a system of international peer review in our research laboratories to help maintain standards."

At the same time, he said, science research had made an attractive career option for students. "But this will not happen unless younger scientists are groomed to take over top positions."