The world's demand on gas is expected to increase in the future as climate change concerns grow, while renewable energy is still expensive to be developed, a prominent economist said here on Friday.

"Demand on gas will be the fastest among other energy sources as it's cheaper than oil and people are more concerned about climate change issue," Cristof Ruhl, the Chief Economist of British Petroleum, a multinational oil and gas company told the press.

According to Ruhl, even though renewable energy is much more environmental friendly, it costs too much to be developed.

"In Brazil, it's worth to use the bio-energy as the country is rich with bio-resources but it costs too much if it's implemented in other countries," said Ruhl.

However, he said, as technology becomes more advanced, it is not impossible that the renewable technology would be much cheaper.

Currently, Ruhl said, the usage of solar, wind and geothermal energies only contribute 1.5 percent of the global energy consumption.

"Renewable energy takes only small share of total energy consumption and for the most part, still requires government support. But from the small base, it continues to grow fast, with global deployment reflecting government support as well as natural endowment," said Ruhl.

According to Ruhl, in contrast to all other fuels, growth in renewable energy was led by the OECD countries, where policy support is the strongest.

"But like other fuels, 2008 saw rapid growth in the first half followed by a marked deceleration towards the end of the year and into 2009," he said.