Half of the UK’s biggest energy companies have all-male boards, sparking calls by industry watchers for quotas to bring more women into the boardroom.

While only eight of the FTSE 100 companies have no women on their boards, 40 of the 80 largest energy firms have no women at all, according to analysis by Powerful Women, a female executive lobbying group.

The privately owned petrochemicals firm Ineos, whose founder Jim Ratcliffe was recently named the UK’s richest person, is among the companies with an all-male board. Others include the fracking company IGas and the North Sea oil producer Hurricane Energy.

The list of laggards is dominated by oil and gas companies, with the exception of the Anglo-Dutch firm Shell, which has six women on its 12-member board. Power supply companies such as E.ON and National Grid top the table for having the highest number of women on their boards.

However, the energy industry still lags behind other sectors, with one-fifth of the 80 biggest companies having only one woman on their board.

Juliet Davenport, the chief executive of the renewable energy supplier Good Energy, said: “It’s extraordinary that half the companies don’t have women on their boards. By doing this, these companies are missing half of the UK population and therefore show a lack of diversity and the potential for groupthink is exacerbated.

“Investors should consider the risks of investing in companies with male-only boards very carefully.”

Simone Rossi, the chief executive of EDF Energy, which is building the Hinkley Point C power station in Somerset, agreed: “We still don’t have enough women in senior positions.”

One leading academic said the numbers showed why quotas were needed. Catherine Mitchell, professor of energy policy at the University of Exeter, added: “Voluntary quotas are insufficient. Quotas for women on boards are necessary.”

“I do not believe for an instant that all men on boards get there on merit alone and therefore quotas are a sensible solution to righting that wrong.”

Last week, five of the big six energy suppliers – EDF Energy, Scottish Power and SSE – committed along with National Grid and Shell to improve gender diversity, although they stopped short of setting hard targets.

•This story was amended on 29 May 2018 to remove an incorrect reference to Cavendish Nuclear Ltd