Hydrogen inefficiency

Hydrogen is inefficient for many tasks:

Battery electric cars are more efficient than hydrogen cars:

Driving a car powered by green hydrogen uses about 2.3 times more renewable electricity than driving with a lithium-ion battery.

Storing energy via pumped hydro is more efficient than via hydrogen:

You can store electricity by pumping water from a low dam to a higher dam and then re-generating electricity by releasing water from the higher dam through a turbine to the low dam. This “pumped hydro” storage loses 19% of the electricity.
Storing renewable electricity by making hydrogen and burning it to re-generate electricity loses 74% of the electricity. Optimistically, this waste could be 65%, but even this is a far greater loss than the 19% loss of pumped hydro. Fortescue plans to burn green hydrogen at Port Kembla.
Storing renewable electricity by making hydrogen and re-generating electricity with a fuel cell wastes 71% of the electricity; optimistically, this waste could be 44%. Again, using pumped hydro is more efficient, wasting only 19%.

In South Australia, they are using electricity to make hydrogen and adding the hydrogen to town gas. It is more efficient to use this electricity in electric home appliances:

Cooking by burning this hydrogen uses about 3.1 times more electricity than cooking with an electric induction cooktop.
Heating a house by burning this hydrogen uses about 6.8 times more electricity than heating with an air conditioner.

The inefficiency of hydrogen may limit Australian hydrogen export to Japan:

Only about 22% of the Australian electrical energy used to make hydrogen ends up as energy of movement for a hydrogen car in Japan.

On this page:

The relevance of hydrogen inefficiencies

I’d like to believe the hype about hydrogen, but I’m concerned about this inefficiency. The low hydrogen efficiencies show that:

using green hydrogen involves building more wind and solar farms to generate between 2.3 and 6.8 times as much electricity and would tie up much more land and capital, and
some anticipated new hydrogen markets and hydrogen production facilities are not robust and could fail because we already have more efficient and well-established alternatives.

While these efficiency calculations are a guide, planners must also consider costs, the environmental impacts of avoided carbon emissions, and the possible environmental impacts of large-scale hydrogen.

The conclusions presented here align with Saul Griffith’s book “The Big Switch” (2022, p 55-60).

Worrying plans for hydrogen: New South Wales

Many governments and companies are trumpeting hydrogen as the future of energy and have plans to use hydrogen in ways that seem inefficient. For example, the “NSW Hydrogen Strategy” targets:

Blending hydrogen into the fossil gas network (hydrogen for home cooking and heating is inefficient),
Building of the Tallawarra B fossil gas/hydrogen generator (storing hydrogen and burning it to generate electricity is inefficient)
Exporting hydrogen (Overseas countries will have the inefficiency of running cars fuelled by Australian hydrogen)

To cover hydrogen activities like these, NSW will need to build between 2.3 and 6.8 times more renewable generation.

The NSW Hydrogen Strategy: October 2021
The Tallawarra generator: Hydrogen will be cover for a new life for fossil fuels: Renew Economy: 5 May 2021

Roles for green hydrogen

Green hydrogen will play a vital role where electricity does not work or is not readily available in large amounts. Australia should use hydrogen where it is efficient, for:

energy export to places like Japan, South Korea and Germany,
hydrogen hubs (to avoid liquefying the hydrogen for distribution),
ammonia fertilisers,
refineries,
shipping,
off-road vehicles,
steelmaking,
the chemicals industry, and
long haul aviation.

Liebreich (2021) considers 35 global uses of clean hydrogen and ranks them by their likely success. His rankings support the conclusions of this webpage:

Hydrogen fuel cell cars are in his least competitive group.
Hydrogen for short-term storage is also in his least competitive group.
Blending hydrogen into the domestic gas network (cooking and heating) is so pointless he does not even rank it.
Hydrogen storage to guard against major disruptions is highly likely but has competitors, including pumped hydro, where the geography allows.

(The clean hydrogen ladder: Liebreich: 29 August 2021)

(Separating hype from hydrogen: The demand side: BNEF: 16 October 2020: Liebreich)

Hydrogen cars: 33% efficient

Look at the efficiency of running a “battery car” versus a “hydrogen car” when you start with renewable electricity.

Energy using steps	Battery car efficiency	Hydrogen car efficiency
Distribution: Get electricity to the car	94%	–
Charge the car battery	95%	–
Store the electricity in the battery	95%	–
Electrolyser: Use electricity to make hydrogen gas	–	76%
Compress hydrogen gas, store it in a high-pressure tank & distribute	–	89%
Fuel cell: Use hydrogen to make electricity	–	54%
Inverter: Convert direct electric current into alternating current	95%	95%
Motor: Use electricity to move the car	95%	95%
Overall Efficiency	77%	33%
Efficiency compared to hydrogen car	2.3	1

(The data comes from Shahan (2021), see the hyperlink in the References section)

To power a car using green hydrogen, you transform renewable energy in the five ways shown in the table:

run an electrolyser using renewable electricity to make hydrogen,
compress the hydrogen into high-pressure tanks, distribute it, and fill the car with it,
run the car fuel cell to use the hydrogen and generate electricity,
convert the direct current into alternating current, and
run the electric motor to move the car.

In each of these steps, you incur a loss of energy. The energy efficiency of each step is the “useful energy output” as a percentage of the “input energy”.

For a hydrogen car, 33% of the renewable electrical energy used to make hydrogen becomes the car’s energy of motion. The remaining energy, 67%, becomes unwanted heat, sound, and movement.

The International Energy Association says the efficiency of fuel-cell electric vehicles is lower than 33%. They say 24% (IEA, 2015, Figure 6: “power to fuel”).

(You get the 33% “overall efficiency from electricity to motion” by multiplying together the efficiencies of the five steps. I explain this type of calculation in a following section.)

A battery car: 77% efficient

To run a lithium-ion battery car, you have two of the same energy transformations as the hydrogen car and three different transformations. In all, 77% of the original electrical energy becomes the car’s energy of motion.

Conclusion: a hydrogen car is inefficient compared to a lithium-ion battery car:

a hydrogen car uses 2.3 times more electricity than a lithium-ion battery car (77 divided by 33 = 2.3),
the electricity needed to drive a hydrogen car 33 km would drive a battery car 77 km,
a green hydrogen car needs 2.3 times more solar panels,
fuelling a green hydrogen car should cost 2.3 times more than a battery car.

This analysis suggests storing electrical energy in a lithium-ion battery rather than hydrogen.

This conclusion seems to be supported by a French decision. The city of Montpellier cancelled buying a fleet of hydrogen buses as electric buses will only cost one-sixth as much.

(Massive hydrogen bus plan scrapped in favour of e-buses: The Driven: 14 January 2022)

The fuel cost for a truck travelling the 960 km trip between Brisbane and Sydney also shows the inefficiency of hydrogen:

battery-electric truck: $320,
diesel truck: $785, &
hydrogen truck: $1,450.

(Janus unveils the first electric truck for a battery swap route on the Australian east coast: The Driven: 10 February 2022)

An excellent video

(Battery electric cars are the best video: CleanerWatt.com: 30 April 2022)

A simple example of an efficiency calculation

Consider an unrealistic process consisting of two steps:

Step 1 is to cut a 4 kg lump of butter in two, drop one half and throw it out, keeping the remaining half, 2 kg of butter. The efficiency of step 1 is the output weight divided by the input weight, 50%.
Step 2 is the same as step 1. You take the surviving 2 kg of butter from step 1, cut it in two, drop one half and throw it out, keeping the other half, 1 kg of butter. The efficiency of step 2 is also 50%.
You now have 1 kg of butter, one-quarter of the original butter.

Arithmetic gets the same answer as common sense by multiplying the efficiencies:

The overall efficiency is 50% multiplied by 50%
= 50/100 multiplied by 50/100
= 0.50 multiplied by 0.50
= 0.25
= One quarter.

Store energy: Pumped hydro: Loss 19%

Pumped hydro generators store electrical energy by using the electricity to pump water from a low reservoir to a high reservoir. Then to generate electricity, they run the water from the high reservoir through a turbine generator and back to the low reservoir.

The Australian National University has identified about 3,000 possible low-cost pumped hydro sites within Australia. Developing about 20 sites alone would support 100% renewable energy generation. Also, investors are keen to back these projects. NSW called for pumped hydro storage proposals and got an overwhelming 28 applications with a capacity of 11 Gigawatts, 5 times the 2 Gigawatts needed to cover the wind and solar projects planned up until 2030.

(NSW flooded by 11 GW of pumped hydro proposals for the state’s big flip to renewables: Renew Economy: 2 November 2021).

A typical round-trip energy efficiency of pumped hydro is 81%, i.e., the energy loss is 19%.

(Blakers, Stocks & Lu (2020) Australian electricity options: pumped hydro energy storage: Australian parliament house research papers: 20 July 2020.)

Australia has so many suitable locations for pumped hydro that it’s pertinent to compare storing energy using hydrogen with pumped hydro storage.

Store energy: Burning hydrogen: Loss 74%

Fortescue plans to build a gas-fired generator at Port Kembla, initially fueled by imported gas and later by green hydrogen. The proposal is to generate renewable electricity, make green hydrogen, and burn the hydrogen to generate electricity again.

(Fortescue to burn green hydrogen in a gas generator at Port Kembla: Renew Economy: 5 October 2021)

This proposal is surprising as generating electricity by burning hydrogen is inefficient. Consider two estimates of the round trip efficiency (RTE) of transforming energy from electricity via hydrogen and a gas turbine to get electricity again.

Process	IEA Efficiency	Optimistic Efficiency
Make green hydrogen using electrolysis and renewable electricity	73%	76% (1)
Store the hydrogen	96%	96%
Transport & distribute the hydrogen	97%	97%
Burn the hydrogen to generate electricity	38%	50% (2)
Overall efficiency	26%	35%
Energy loss	74%	65%
The superiority of pumped hydro	3.1	2.3

The IEA efficiencies are from the International Energy Agency report (IEA, 2015). Professor Blakers of the Australian National University (Blakers, 2021) sets hydrogen round trip efficiency at 25%, consistent with the IEA figures.

The “Optimistic efficiency” is based on data from the upper range of estimates to consider an optimistic case for hydrogen.

(1) The electrolysis efficiency is 76% from Shahan (2021), not 70% from Barnard (2018),
(2) The gas generator efficiency is 50%, high in the 34% to 51% range from Albatayneh (2020, p.671).

(Hyperlinks to the referenced articles, e.g., Barnard (2018), are in the reference section below)

Storing renewable electricity by making hydrogen and burning it to re-generate electricity loses 74% of the electricity. This hydrogen energy storage uses 3.1 times more electricity than pumped hydro energy storage. Using pumped hydro is far more efficient, only wasting 19%.

Optimistically this waste could be 65% rather than 74%.

We have two plans to build gas generators that will eventually use green hydrogen: (1) Fortescue at Port Kembla and (2) Origin Energy’s Tallawarra B gas generator.

Store energy: Hydrogen fuel cell: Loss 71%

Rather than burning the hydrogen in a gas-fired generator, using a fuel cell to generate electricity is more efficient. Consider two estimates of the round trip efficiency (RTE) of transforming energy from electricity via hydrogen and a fuel cell to get electricity again.

Process	IEA Efficiency	Optimistic Efficiency
Make green hydrogen using electrolysis and renewable electricity	73%	76% (1)
Compress & store the hydrogen	92%	92%
Generate electricity from hydrogen in a fuel cell	43%	80% (2)
Overall efficiency	29%	56%
Energy loss	71%	44%
The superiority of pumped hydro	2.8	1.4

The “IEA efficiency” is from the International Energy Agency report (IEA, 2015).

The “Optimistic efficiency” is based on data from the upper range of estimates to consider an optimistic case for hydrogen.

(1) The electrolysis efficiency is 76% from Shahan (2021), not 70% from Barnard (2018),
(2) The fuel cell 43% comes from Gencell (2021), which gives the specifications of three types of hydrogen fuel cells with efficiencies ranging from 30% to 80%. (See the table at the end of the article). Stationary fuel cells reach this 80% efficiency by using the heat generated by the fuel cell; however, fuel cells in cars cannot use that heat and have a lower efficiency of 42%.

The theoretical maximum efficiency of a hydrogen fuel cell is 85% (Barnard, 2018). So, it’s only the best stationary fuel cells that get to 80% efficiency and this fuel cell efficiency alone (ignoring the efficiency of electrolysis and compressing the hydrogen) makes this round-trip efficiency lower than 81% efficiency pumped hydro.

Storing renewable electricity by making hydrogen and re-generating electricity with a fuel cell loses 71% of the electricity, using 2.8 times more electricity than pumped hydro. Again, it’s more efficient to use pumped hydro, losing only 19%.

Optimistically this waste could be 44% rather than 71%.

(Gencell (2021) Comparing fuel cell technologies: Retrieved October 2021: See Table at the end of the article)

These calculations suggest that storing energy via pumped hydro is more energy-efficient than storing energy by making hydrogen, even when using assumptions favouring hydrogen. Australia should use pumped hydro rather than less efficient hydrogen storage.

Store energy: Emerging technologies

Due to the energy inefficiency of hydrogen, hydrogen storage investment will also be vulnerable to emerging technologies. Some challengers could be:

The company MGA Thermal, based in Newcastle, NSW, is developing Miscible Gap Alloy blocks. These blocks could store energy from intermittent renewables to power existing coal or gas generators.
The company 1414 Degrees, based in Adelaide, is moving towards commercial-scale heat storage using molten silicon.
Form Energy is developing cheap, long-duration iron-air batteries.
Mercedes-Benz is using solid-state lithium-ion batteries in its eCitaro electric buses.

Injecting green hydrogen into town gas

In South Australia, AGN adds green hydrogen into town gas, distributing a blend of 5% hydrogen and 95% methane to homes. And the gas industry is pushing for 100% hydrogen in town gas!

The following calculations indicate that using hydrogen in town gas is highly inefficient compared to using electricity for home cooking and heating.

(Australia’s largest electrolyser switches on to pipe green-hydrogen into homes: Renew Economy: 19 May 2021)
(Hydrogen projects in South Australia: Renew Economy: SA Government)
(St. John, J. (2020) Green hydrogen in natural gas pipelines: Decarbonisation solution or pipedream.)

Cook by burning hydrogen: 22% efficient

Compare cooking with hydrogen and an electric induction cooktop. First, work out the efficiency of using a gas cooktop burning green hydrogen.

Process	Efficiency	Source
Make green hydrogen using electrolysis and renewable electricity	76%	Shahan (2021)
Store the hydrogen	95%	Guided by Shahan (2021)
Burne the hydrogen to heat water	31%	Livchak et al. (2019, p 11)
Overall efficiency	22%

Cook using induction: 69% efficient

Now work out the efficiency of using an induction cooktop and pumped hydroelectricity.

I want to compare like with like, so, as it may be possible to store the blended town gas, I’ve assumed that the induction cooktop uses electricity from stored energy, i.e., from a pumped hydro generator.

Process	Efficiency	Source
Pumped hydro	81%	Blakers (2020)
Induction cooktop: electricity to heat water	85%	Livchak (2019, p.11)
Overall efficiency	69%

Conclusion: Burning green hydrogen from the blended town gas on a gas kitchen cooktop is inefficient: it uses 3.1 times more electricity than an induction cooktop. (69 divided by 22 = 3.1)

Heat by burning hydrogen: 54% efficient

Compare heating a house with hydrogen and an air conditioner. First, work out the efficiency of burning green hydrogen from the blended town gas.

Process	Efficiency	Source
Electrolysis: electricity to hydrogen	76%	Shahan (2021)
Hydrogen storage	95%	Guided by Shahan (2021)
A flued gas heater 70 – 80%	75%	Brakels (2021)
Overall efficiency	54%

Heat with air conditioning: 365% efficient

Now work out the efficiency of heating using an air-conditioner powered by electricity from a pumped hydro generator.

An air conditioner (heat pump) heats a house by gathering heat from the external air and releasing the heat inside the house. An air conditioner can gather 4.5 times more heat energy than the electrical energy it uses, giving an efficiency of 450%.

Process	Efficiency	Source
Pumped hydro	81%	Blakers (2020)
Air-conditioner: 300-600%	450%	Heating & Cooling (2021)
Overall efficiency	365%

Conclusion: Burning green hydrogen from the blended town gas to heat a house is inefficient: it uses 6.8 times more electricity than an air conditioner. (365 divided by 54 = 6.8)

Putting hydrogen into town gas pipelines

The natural gas piped around Australia is mostly methane. Hydrogen holds far less energy per unit volume than methane, 3.3 times less. So, for the pipelines to carry the same energy, the pipes would have to transport 3.3 times the volume of gas, significantly increasing the cost of pumping town gas. Also, many pipelines would need larger diameter pipes, an expensive, long-term project. Another concern is that hydrogen can attack the structure of metal or polythene pipelines.

(Hydrogen or electron economy: Centre for Sustainable Road Freight: 31 December 2020)
(St. John, J. (2020) Green hydrogen in natural gas pipelines: Decarbonisation solution or pipedream: Green Tech media: 30 November 2020)

Hydrogen cars in Asia using our hydrogen: 22% efficient

Consider making green hydrogen in Australia, liquefying it, shipping it to Japan, and then using it to run a car. To transport hydrogen, it’s liquified by cooling it to minus 253 degrees C. This liquefaction uses about 30% of hydrogen’s energy: an efficiency of 70%.

Process	Efficiency	Source
Liquefaction of hydrogen	70%
Shipping uses 5% of the energy	95%	Unsourced
The efficiency of a hydrogen car	33%	From above
Overall efficiency	22%

Only about 22% of the Australian electrical energy used to make hydrogen ends up as energy of movement for a hydrogen car in Japan. This inefficiency of hydrogen may prevent the emergence of this export market.

Shipping ammonia overseas

You can transport energy by converting electricity to hydrogen and then ammonia which is easier to ship. Despite ammonia being far easier to liquefy than hydrogen, the efficiency of using ammonia seems much the same as hydrogen.

We can use ammonia in several ways with different efficiencies:

electricity to hydrogen to ammonia to pure hydrogen used in a fuel cell vehicle: 11% – 19%,
electricity to hydrogen to ammonia to pure hydrogen used in a stationary fuel cell: 21.4% electricity plus 17.9%, a total of 39.3%,
electricity to hydrogen to ammonia burned in a gas turbine: 24% – 31%, and
electricity to hydrogen to ammonia burned in an internal combustion vehicle: 15% – 21%.

These are from a CSIRO paper, “Ammonia as a Renewable Energy Transportation Media.” cited in Brown (2017)

(Brown, 2017, Round-trip Efficiency of Ammonia as a Renewable Energy Transportation Media: Ammonia Energy Association”)

The round trip efficiency of liquid ammonia is 11-19%, which is similar to the round trip efficiency of liquid hydrogen, 9-22%

(El Kadi, Smith & Torrenete-Murciano, 2020, hydrogen and ammonia: the perfect marriage in a carbon-free society: The Chemical Engineer)

The above alternatives do not include using ammonia in a fuel cell. Patonia (2020) states that ammonia is best as a hydrogen carrier rather than as:

a fuel for burning that releases nitrogen oxides, or
used in a fuel cell, which could limit the nitrogen oxides and give better efficiency, but has technical challenges.

(Patonia: 2020: November: Ammonia as a storage solution for future decarbonised energy systems: The Oxford Institute for energy studies.)

If you find articles countering these conclusions, please let me know so I can improve this page.

Energy for desalination

An electrolyser needs water to make hydrogen, 9 kg of pure water per kg of hydrogen. Surprisingly, you can ignore the electricity used to make this water. You can ignore it because making hydrogen from water uses a much larger amount of electricity.

(Electrolysis uses about 48 kWh per kg of hydrogen, while desalination uses about 0.004 kWh per kg of hydrogen.)

Hydrogen’s expanded role would use less water than the current coal industry, about one-quarter.

Petrol engine energy loss: 73% – 89%

The “well-to-wheel” energy efficiency of a petrol-driven car is between 11% and 27%. (Albatyneh et al., 2020, in the abstract), so the energy loss is between 73% and 89%. We have used low-efficiency fossil fuels for a long time, but for many tasks, we now have far more efficient alternatives than both fossil fuels and hydrogen, so the hydrogen economy may not take off.

The well-to-wheel efficiency of a car considers the energy:

used to extract the oil from the oil well,
used to refine the oil,
used to distribute the petrol,
contained in the petrol, and
supplied to the car wheels to move the car.

Hydrogen: Climate risks

Hydrogen could play an essential role in supplying energy to the world. This role would bring occasional significant hydrogen escapes and ongoing hydrogen leaks, e.g., from aging, re-purposed town gas pipes. So, we need to understand the impact of this on our atmosphere.

Over the past 25 years, atmospheric hydrogen gas has increased by 4%, and scientists do not understand what is driving this.

Scientists do know that hydrogen could damage our atmosphere. The hydroxyl radical (OH) cleanses the atmosphere of greenhouse gases like methane and toxic gases like carbon monoxide. An increase in hydrogen could decrease hydroxyl radicals and increase the levels of damaging gases like methane and carbon monoxide.

A further concern is that when you (1) convert the hydrogen into ammonia and then (2) either burn the ammonia or use it in a fuel cell, this can release nitrogen oxides. These oxides are bad for health, can attack ozone, and add to greenhouse heating.

The massive use of hydrogen may not be “clean”.

(Don’t rush into a hydrogen economy until we know all the risks to our climate: The Conversation: Pearman & Prather: 10 August 2020)

Making green hydrogen more competitive

The cost of producing green hydrogen is $5/kg, which needs to fall to $2/kg to compete with fossil fuel hydrogen. To make green hydrogen competitive with fossil fuel hydrogen, you need to improve the electrolyser efficiencies and decrease the cost of solar and wind generation. (Note, a carbon price would help!)

To make green hydrogen more competitive with batteries and pumped hydro, you need to increase the efficiency of (1) electrolysers producing hydrogen from electricity, (2) storage of hydrogen, and (3) the fuel cells generating electricity from hydrogen.

We do not need new hydrogen markets to enable large-scale green hydrogen production with its cost reductions to compete with fossil fuel hydrogen. We do not need these new markets as the current global hydrogen demand is large. To meet this global demand would use a large amount of renewable energy generation: 1.6 times the 2020 global wind and solar generation.

You could also reduce the cost of green hydrogen by paying electrolysers to slow production during electricity scarcity. With large-scale hydrogen production, we would have considerable ability to slow production. The electrolysers would earn money by making electricity available to others, acting as virtual batteries. Woodside is planning to use electrolysers like this in the Perth grid, making green hydrogen. Unfortunately, they also plan to produce hydrogen from fossil fuels.

The inefficiency of hydrogen is an advantage for our industry

The inefficiency of green hydrogen/ammonia and the energy involved in exporting them give Australian industries an advantage: cheaper electricity than in countries that import hydrogen. This cost advantage could allow Australia to process more minerals in Australia rather than simply being a quarry. We would then be exporting more renewable energy embedded in processed minerals.

Why is so much money going into hydrogen

The above simple energy calculations suggest that hydrogen is inefficient for:

storing energy,
powering a car,
generating electricity,
heating homes, and
cooking on a stovetop.

Companies like BHP, Fortescue, and Macquarie have plans to produce green hydrogen. There are plans for 35 electrolysers, many with an enormous capacity.

(Australia has 38GW of green hydrogen in the pipeline, but major cost falls are needed: Renew Economy: 11 June 2021)

Surely these organisations know what they are doing.

In some regions, hydrogen may be the best alternative, e.g., where pumped hydro storage is impossible or installing electric vehicle charging is difficult. Hydrogen carries a huge amount of energy per unit mass; filling hydrogen cars is quicker than charging electric vehicles.

Some authors are concerned that fossil fuel companies may be backing the hydrogen economy to (1) sell hydrogen produced from fossil fuels or (2) use their gas pipelines and sell gas.

(The Federal Coalition is pushing dirty hydrogen made from LNG: The Age: 13 October 2021)
(Beware fossil gas suppliers bearing hydrogen gifts: Renew Economy: Tim Forcey: 26 October 2018)

I would like the green hydrogen economy to succeed, but I’d like to understand how it can compete, given its apparent inefficiency.

Maximum electrification

Blakers (2021) says that Australia can rapidly and cheaply cut 80% of our greenhouse emissions by electrification using mature, low-cost, and reliable technology:

installing:
- wind and solar farms,
- transmission lines, and
- pumped hydro and batteries,
moving to electric vehicles, and
electrifying heating.

This electrification would:

reduce our development of inefficient hydrogen infrastructure, like:
- hydrogen refuelling stations for cars, and
- hydrogen blending into town gas,
build a green electricity grid, and
supply cheap power to foster the expansion of Australian industries like mineral processing and green hydrogen production.

References

Albatayneh, A. et al. (2020) Comparison of the overall energy efficiency of internal combustion engine vehicles and electric vehicles, Environmental and Climate Technologies, vol 24, no 1, pp 669-680: Retrieved from Sciendo Oct 2021.

Blakers, A. Stocks, M. & Lu, B. (2020) Australian electricity options: pumped hydro energy storage, Australian Parliamentary Library 20 July 2020

Blakers (2021) Australia can achieve rapid, deep, and cheap emission cuts from the technology we have now: Renew Economy: 7 September 2021.

Barnard, M. (2018) What are the pros and cons of using hydrogen to generate electricity, from Forbes, 8 May 2018

Brakels, R. (2021) Air Conditioners Will Heat Your Home Cheaper Than Gas. Here’s Why. Solar Quotes, 23 August 2021

Heating & Cooling (2021) Australian Government, Dept of Industry, Science, Energy & Resources: Retrieved October 2021

IEA (2015) International Energy Agency: Hydrogen and Fuel Cells Technology Roadmap: Figure 6, Page 21

Livchak, Hedrick & Young (2019) Residential Cooktop Performance and Energy
Comparison Study, Frontier Energy report, July 2019

Shahan, Z. (2021) Chart: Why battery electric vehicles beat hydrogen-electric vehicles without breaking a sweat from CleanTechnica, 1 February 2021

An overview of Australia’s progress toward renewable energy superpower

Updated 12 February 2022