Hydrogen and energy

Why use renewable energy to make hydrogen?

As more and more renewable energy, wind, solar PV, solar thermal, wave and others are built, there will be an increasing need to store excess energy when generation is greater than demand.

At present there are times in South Australia, where an average of half of the electricity is generated by wind and solar, when wind turbines have to be turned off because there is too much power being generated.

Some excess energy can be sent elsewhere (interstate in the case of South Australia), but this is limited by the capacity of the power interconnectors, some can be stored in batteries, some in pumped hydro systems, and some can be converted to hydrogen.

What can hydrogen be used for?

Some uses of hydrogen:

• It can be injected into an existing natural gas system, mixed with the predominantly methane natural gas; hydrogen, weight-for-weight, produces more heat when burned than any other fuel;
  
  
• It can be combined with nitrogen to produce ammonia, which has many uses and potential uses and is easy to ship around the world;
  • Ammonia can be broken down to recover the hydrogen;
  • Ammonia can be used to produce nitrogenous fertilisers and explosives;
  • Ammonia can be burned in internal combustion engines (with no carbon dioxide emissions);
  • Ammonia has many other uses.
  
  
• It can be burned to power turbines and generate electricity;
  
  
• It can be stored in underground formations for later use;
  
  
• It can fuel vehicles using fuel cells.

• The production of hydrogen, as of the time of writing this section if it is to be done sustainably, is not energy efficient.
  
  
• While a kilogram of hydrogen can yield more energy when combined with oxygen than a kilogram of any other common fuel (and far more energy than a kilogram of batteries), it does require a lot of space to store. Liquifying it requires extremely low temperatures and storing it as a gas under very high pressure requires heavy tanks. It can be stored as metal hydrides, but this too requires heavy storage systems.
  
  Hydrogen can be converted to ammonia by combining it with nitrogen. Ammonia is much easier to store and transport than is hydrogen. Ammonia can easily be converted back into hydrogen and nitrogen, but there are challenges in removing the nitrogen and all traces of the ammonia. Of course energy is required in both conversions.
  
  
• If hydrogen is in contact with iron or steel (especially when under high pressure?) it can combine with the iron to form brittle iron hydrides that then weaken the metal.
  
  
• The very low density of hydrogen gas makes piping it or transporting it by road, rail or ship, expensive.
  
  
• Burning hydrogen to produce electricity is inefficient (as is burning any fuel to produce electricity). Using it in a fuel-cell system is also inefficient. (However, burning it to produce heat is very efficient.)

Related pages on external sites

Hydrogen for Australia's Future: A briefing paper for the COAG Energy Council; Prepared by the Hydrogen Strategy Group chaired by Australia's Chief Scientist, Alan Finkel, August 2018.
Vision Statement: Our vision is a future in which hydrogen provides economic benefits to Australia through export revenue and new industries and jobs, supports the transition to low emissions energy across electricity, heating, transport and industry, improves energy system resilience and increases consumer choice.
The Key Opportunity: To capture the hydrogen export market and associated benefits in the domestic economy.

16 renewable hydrogen projects backed by ARENA grants, written by Sophie Vorrath in Renew Economy, 2018/09/06. "... ARENA said the R&D projects targeted by the funding covered a diverse range of solutions, with at least one from each point in the supply chain: production, hydrogen carrier, and end use."

Queensland to invest in exploring hydrogen energy, AAP, 2018/05/31. "The Queensland government has announced $750,000 will be allocated in next month's state budget to start developing hydrogen as a viable renewable energy source."

Carbon Commentary, by Chris Goodall; Hydrogen made by the electrolysis of water is now cost competitive and gives us another building block for the low-carbon economy.

Electrolysis of Water; Wikipedia

Assessment of the cost of hydrogen from photovoltaic electricity, Australian Renewable Energy Authority.

Hydrogen production from coal gasification, USA Office of Energy Efficiency and Renewable Energy.

AGL's media release on the hair-brained brown coal to hydrogen project in Victoria. AGL recognises the need for carbon capture and storage if the project goes full scale. They have not providing funding for the pilot coal-to-hydrogen project to be built in Victoria but are providing a site and the needed coal. AGL is the biggest producer of greenhouse gasses in Australia but is aggressively pursuing sustainable alternatives to coal-fired power generation. They have promised to phase out coal for power generation, but not until 2050, which is far later than needed.

A drone powered by a combination of hydrogen fuel cell, super capacitor and battery. University of Sydney aerospace engineering PhD candidate Andrew Gong, September 2018.

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