Tens of billions of dollars of new investment is needed in LNG projects to avoid a supply crunch in the 2020s, Royal Dutch Shell Plc (NYSE: RDS.A) has warned.

The global market is still absorbing supplies from a wave of LNG megaprojects built in Australia over recent years, as well as the emergence of the U.S. as a net gas exporter for the first time in more than half a century.

But Shell, one of the world’s largest suppliers of LNG, said renewed investment was needed to meet surging demand from China and other developing countries.

Steve Hill, head of Shell’s gas trading and marketing business, said the LNG market was absorbing “quite comfortably” an unprecedented increase in supplies from new projects such Chevron Corp.’s (NYSE: CVX) Gorgon and Wheatstone developments in Australia.

Shell, Chevron and other big LNG producers such as Total SA (NYSE: TOT) and ExxonMobil Corp. (NYSE: XOM) have put the brake on further investment because of concern that the Australian projects, together with rising U.S. gas exports, would lead to a supply glut.

LNG prices have fallen sharply since 2014 in parallel with oil but both markets have staged a partial recovery over the past year and Hill indicated that Shell was beginning to refocus on the case for renewed expansion.

While 50 million tonnes per annum (mtpa) of LNG supply has come onstream in the past two years stemming from investment decisions made years earlier, only 7 mtpa of additional capacity has been approved for development during the same period, Hill noted.

“We’ve had a hiatus in the past two years,” he said. “Something needs to happen to avoid a supply crunch in the next decade.”

Maarten Wetselaar, director of Shell’s integrated gas business, said an extra 200 mtpa of LNG capacity was needed by 2030—equivalent to about 20 large projects, each of which has typically cost about $10 billion to develop in the past.

These liquefaction facilities condense gas into a supercooled liquid form which can be transported long distances by ship. Shell has proposed LNG plants awaiting investment decisions in the U.S. and Canada as well as projects at an earlier stage of planning in Indonesia, Tanzania and Australia.

Wetselaar acknowledged that Shell had the capacity to embark on new projects as it neared the end of its existing development program with the planned start of production from the Prelude LNG facility in Australia later this year. However, he said Shell was still working to reduce the cost of future projects before approving them.

Global gas demand will grow at an average 2% per year between 2017 and 2035, double the rate of overall energy demand, according to Shell’s latest outlook for the LNG market issued on Feb. 26. In Asia, gas demand will grow at an average 3% over the period.

Gas demand from China increased 15% last year alone and LNG imports rose 50%, reflecting the push by Beijing to tackle air pollution by replacing coal with cleaner sources of energy.

Shell and other big LNG investors are counting on demand for gas outlasting other fossil fuels because it emits less carbon dioxide and pollutants than coal or oil when used to generate electricity or to fuel trucks and ships.

Wetselaar acknowledged that the LNG market was becoming more competitive with proliferating sources of supply, including low-cost U.S. shale gas, and technological disruption from renewable power. This was causing a shift to shorter-term supply contracts and spot pricing which gave LNG developers less certainty than they have had when making investment decisions in the past.

But Wetselaar said the demand outlook was strong enough to support new projects. “We are confident that the industry will solve this and that the money will be there. People need to get use to the risk-reward profile.”