Developing demand is essential to get the ball rolling. Using hydrogen in industries that would be impossible or too costly to electrify will drive growth.

Following are some ground-breaking projects underway worldwide.

SAUDI ARABIA: GREEN AMMONIA

Saudi Arabia's Neom planned city is working with the kingdom's ACWA Power and U.S. chemicals firm Air Products on a $5 billion project to build a 1.2 million tonnes a year green ammonia plant, which will use hydrogen produced from an electrolyser powered by more than 4 GW of solar, wind and storage. Production is due to begin in 2025.

CHINA: GREEN HYDROGEN

State-owned Beijing Jingneng Power Co is building a 23 billion yuan ($3.5 billion) green hydrogen plant in Inner Mongolia, to be powered by 5 gigawatt (GW) of solar and wind energy. The plant, due to be completed in 2021, will have a capacity of 500,000 tonnes of hydrogen a year.

JAPAN/AUSTRALIA: HYDROGEN FROM BROWN COAL

A A$500 million ($370 million) pilot project, led by Kawasaki Heavy Industries and backed by the Japanese and Australian governments, plans to ship its first cargo of hydrogen extracted from brown coal in Australia's Victoria state in March 2021.

The shipment would be on the world's first dedicated hydrogen carrier, KHI's Suiso Frontier. If the project goes commercial, it aims to capture and bury carbon dioxide released in the process under the seabed off the coast of Victoria.

NORWAY: GREEN AMMONIA

Norwegian chemicals group Yara plans to convert its Porsgrunn ammonia plant by 2026 to make ammonia from green hydrogen produced by electrolysis powered by renewable energy. The plant produces 500,000 tonnes of ammonia a year.

SWEDEN: HYBRIT GREEN STEEL

Swedish venture HYBRIT, owned by SSAB, state-owned utility Vattenfall and miner LKAB, began test operations at a 1.4 billion crown ($165 million) green steel pilot plant in August. SSAB aims to have fossil-free steel commercially available by 2026.

SCOTLAND: HYDROGEN IN HOMES

Scotland is running the world's first trial of 100% green hydrogen instead of gas for cooking and heating in 300 homes, in a project backed by Britain's Office of Gas and Electricity Markets.

SOUTH KOREA: HYDROGEN REFUELING

Hydrogen Energy Network, or HyNet, is a joint venture of 13 companies led by Hyundai Motor Co, Korea Gas Corp and Air Liquide Korea, backed by the South Korean government. It plans to install 100 hydrogen refueling stations in the country by 2022.

UNITED STATES: GREEN POWER

The Long Ridge Energy Terminal, under construction in Ohio, will have a 485-megawatt natural gas power plant designed to run entirely on hydrogen within a decade. The plant, set to begin operating in late 2021, will initially blend hydrogen into its gas stream. Long Ridge is owned by a unit of Fortress Transportation and Infrastructure Investors LLC and an affiliate of Chicago-based asset management firm GCM Grosvenor.

($1 = 1.3466 Australian dollars)

(Compiled by Sonali Paul; Additional reporting by Nichola Groom in Los Angeles and Muyu Xu in Beijing; editing by Richard Pullin)