Sustained prices above $95 per barrel, however, may make extraction economically attractive in the coming years.
We are past whether this is an economically attractive deal.
Tax abatements and other government incentives are credited with making some new projects economically attractive.
He said last year's stock levels were artificially inflated because of economically attractive prices.
Of particular interest in the project is whether the recycling can become economically attractive.
"But that doesn't mean that economically attractive opportunities won't be taken advantage of," he added.
The final aim is to provide a storage technology that is attractive both economically and environmentally.
He believes that, with continuing government support, huge solar farms will become economically attractive in Japan for the first time.
Building solar power stations in space was economically attractive when energy prices spiked during the 1979 oil crisis.
They may still be economically attractive fuels however, particularly in combined-cycle plants.