HOUSTON, Nov 13 (Reuters) - Global oil demand will fall

to around 80 million barrels per day by 2035 in a net-zero

environment, and 100 million bpd in the current trajectory

scenario, BP's chief U.S. economist told an energy

conference in Dallas on Wednesday.

Crude oil demand is about 102 million bpd now, and the

forecast assumes renewables and more efficient motor vehicles

increase over that period. But BP's Michael Cohen said the world

will need continued investment in fossil fuels to ensure an

orderly transition to cleaner energy.

Non-OPEC oil supply growth will exceed demand growth over

the next several years, limiting the ability of the Organization

of the Petroleum Exporting Countries to add more barrels to the

global market, Cohen said.

Market changes also will produce a shift in output and

configurations at oil refineries. Refiners will shift their

plants to produce more naphtha to replace gasoline, and there

will be greater integration of oil and petrochemical operations,

Cohen said.

The portion of gasoline compared with other refined products

supplied by refiners will drop to about 15% by 2050, from 25%

today, he said. Automakers will continue to build internal

combustible engine vehicles, and there will be more miles driven

worldwide, Cohen said, but light vehicles will be more

fuel-efficient.

The drop in gasoline demand will particularly affect

European refineries, Cohen said.

"The Atlantic Basin component of refining throughput

declines is the largest of any of the different regions," said

Cohen.

While investment in oil and gas production will remain

stable, there will be a massive increase in spending on

renewable energy, he said.