Erecting wind turbines on the world’s best offshore sites could provide more than enough clean energy to meet global electricity demand, according to a report.

A detailed study of the world’s coastlines has found that offshore windfarms alone could provide more electricity than the world needs – even if they are only built in windy regions in shallow waters near the shore.

Analysis by the International Energy Agency (IEA) revealed that if windfarms were built across all useable sites which are no further than 60km (37 miles) off the coast, and where coastal waters are no deeper than 60 metres, they could generate 36,000 terawatt hours of renewable electricity a year. This would easily meeting the current global demand for electricity of 23,000 terawatt hours.

“Offshore wind currently provides just 0.3% of global power generation, but its potential is vast,” the IEA’s executive director, Fatih Birol, said.

The study predicts offshore wind generation will grow 15-fold to emerge as a $1tn (£780bn) industry in the next 20 years and will prove to be the next great energy revolution.

The IEA said earlier this week that global supplies of renewable electricity were growing faster than expected and could expand by 50% in the next five years, driven by a resurgence in solar energy. Offshore wind power would drive the world’s growth in clean power due to plummeting costs and new technological breakthroughs, including turbines close to the height of the Eiffel Tower and floating installations that can harness wind speeds further from the coast.

The next generation of floating turbines capable of operating further from the shore could generate enough energy to meet the world’s total electricity demand 11 times over in 2040, according to IEA estimates.

The report predicts that the EU’s offshore wind capacity will grow from almost 20 gigawatts today to nearly 130 gigawatts by 2040, and could reach 180 gigawatts with stronger climate commitments.

In China, the growth of offshore wind generation is likely to be even more rapid, the IEA said. Its offshore wind capacity is forecast to grow from 4 gigawatts to 110 gigawatts by 2040 or 170 gigawatts if it adopts tougher climate targets.

Birol said offshore wind would not only contribute to generating clean electricity, but could also offer a major opportunity in the production of hydrogen, which can be used instead of fossil fuel gas for heating and in heavy industry.

The process of making hydrogen from water uses huge amounts of electricity but abundant, cheap offshore wind power could help produce a low-cost, zero-carbon alternative to gas.

In the North Sea, energy companies are already planning to use the electricity generated by giant offshore windfarms to turn seawater into hydrogen on a floating “green hydrogen” project, backed by the UK government. The clean-burning gas could be pumped back to shore to heat millions of homes by the 2030s. The UK has committed to reaching net zero carbon emissions by 2050.

The overlap between the UK’s declining oil and gas industry and the burgeoning offshore wind sector could offer major economic benefits for the UK, Birol said.

“Offshore wind provides a huge new business portfolio for major engineering firms and established oil and gas companies which have a strong offshore production experience,” he said. “Our analysis shows that 40% of the work in offshore wind construction and maintenance has synergies with oil and gas practises.”