A Cold, Hard Look at Renewable Gases

The push to renewable gas has caused many in the plumbing industry to fits of head-scratching as state governments ban gas connections to new domestic and commercial premises. While the NSW government has wisely avoided this policy decision, many local government councils have bypassed state law and banned gas through their development control plans (DCPs) on the questionable grounds of health risks and economic benefit.

In recent years, the renewable gas challenge has been taken up by major gas providers all over the country, who have created world class production and demonstration facilities for the two leading renewable gas candidates: hydrogen and biomethane.

But why should we ban the use of existing sources of gas? What is hydrogen and biomethane? Which renewable gas is more potent, producible at scale, energy efficient, and reliable? Are there pros and cons to each?

What follows is an overview of the two renewable gases, with a comparison against the two existing forms of gas available in Australia, natural gas (NG) and liquified petroleum gas (LPG).

Hydrogen is the most abundant chemical on the planet, a colourless, odourless, tasteless, flammable gas. It is an excellent clean-burning energy source. Hydrogen is the most abundant chemical on earth, though not in gas form.

Biogas can exist in two different forms: Raw biogas, which is a naturally occurring gas that comes from the breakdown of organic matter such as compost heaps, swamps, human and animal waste. It is human, animal and plant waste that can be used to produce biogas for energy. Then there is purified biomethane (biogas as it is commonly understood), which is produced from raw biogas.

Heat Values/Energy Value

Firstly, we need to consider the raw energy output of each gas per unit of volume. Gas energy output is known as it’s ‘heat value’, which is how much energy it can produce when burned. According to the table below, the traditional gases (LPG and natural gas) are the far more potent than both renewable gases in terms of raw energy output by volume. Both renewable gases perform poorly when compared to the natural gas and LPG.

Many proponents of hydrogen will correctly point out that hydrogen has a higher energy content than other gases, but this, while indisputable, is a fact often misrepresented or misunderstood. It needs to be highlighted that hydrogen has a higher energy content by mass, and not by volume. When the properties of natural gas and hydrogen are compared, it becomes clear that contains less mass than natural gas. This is why it is important to compare the energy production value of each gas by volume, as in the table above. Approximately 3x as much volume of hydrogen must be burned to produce the same amount of energy as natural gas [1].

In a comparison from another perspective, the table below demonstrates how much usage time (in minutes and hours) 1m3 of each gas will deliver for a common gas appliance, a Rheem Stellar 5 Star 265 Gas Water Heater (which has a gas consumption of 30Mj/h).

How is it produced?

Fortunately, both renewable gases in their simplest form are in extremely abundant supply. As noted, hydrogen is the planet’s most abundant element, and biogas is produced largely from human sewage, something of which there will never be a shortage.

Hydrogen

The easiest way to produce or capture hydrogen in gaseous form is by splitting water into its singular elements – two parts hydrogen and one part oxygen (hence H2O). During this process, oxygen is returned to the air and hydrogen is stored for use. There are two methods for capture.

♦ Electrolysis (the most common method) which uses a strong electric current passing through a tank of water (note that the water must be distilled – more on this later) to achieve this [2].

♦ A chemical reaction from a fossil fuel such as coal (coal gasification) or natural gas (steam methane reformation) and water.

There are four different forms of hydrogen available, and they are defined by their method of production and greenhouse gas emissions profile [3].

♦ Green hydrogen: Produced from water via electrolysis, using renewable energy as a fuel source. Does not produce emissions.

♦ Blue hydrogen: Produced from natural gas via a process called ‘steam reforming’. This process produces emissions that are captured using carbon capture and storage technologies.

♦ Grey Hydrogen: Produced from natural gas using steam reforming also. This process releases emissions into the atmosphere.

♦ Brown/Black hydrogen: Produced from brown/black coal via a process called ‘gasification’. This process produces emissions that are produced and released into the atmosphere.

 

Biogas is produced commercially from human waste as a supplement to the gas network. It must be upgraded to pure methane form (also known as purified biomethane) from raw biogas. During the primary treatment phase a sludge is produced which gives off raw biogas consisting of methane, carbon dioxide, and moisture plus traces of hydrogen sulphide, siloxane plus other contaminants and impurities. These non-methane products must be removed to achieve standards that meet “the gas composition limits per Australian Standard AS 4564: 2020 Specification for general purpose natural gas”. The biomethane produced is then injected into the gas distribution network [4]. 

Producing each renewable gas comes at a cost, in both financial and energy terms. An important question to ask is: What resources are required to produce each respective gas?

Hydrogen

To produce hydrogen requires two main ingredients: water and electricity. As previously mentioned, electrolysis is the main method for extracting hydrogen gas from water.

Water: A lot of water is needed to extract hydrogen in gaseous form. In the NSW Government’s Hydrogen Strategy (October 2021) – an assumption is made that nine litres of water are required to produce one kilogram of hydrogen (9L/kg) [5]. However, it is not just water that is required for electrolysis, but distilled or purified water. This is water that has had minerals and impurities removed that may otherwise damage the electrolyser or reduce its efficiency.

Some industry professionals estimate that to produce one litre of purified water for the purposes of electrolysis requires two litres of regular water. This means that the actual water requirement for hydrogen production would be closer to 18L/kg (not accounting for wastage).  Some may think that purifying this much water for electrolysis is wasteful, particularly in drought-prone Australia.

Electricity: With existing electrolyser technology, the electricity requirements for production of green hydrogen at scale are not favourable. Electrolysers available on the market today operate at efficiencies close to 75% (with electricity requirements of 52.5 kWh/kg hydrogen). This is not a great trade-off [6]. Using kWh/kg conversion rates, one kilogram of hydrogen can produce 39.4 kWh energy. Therefore, the energy trade-off looks like this:

52.5kWh electricity INPUT = 39.4 kWh hydrogen energy OUTPUT

The good news is that efficiency is improving, with Wollongong-based startup Hysata’s new type of electrolyser boasting a 95% (41.5 kWh/kg) efficiency, well ahead of other competitors. This technology has not been demonstrated at scale however, with current electrolysers producing around 0.2mW power output. Hysata have received funding to develop a commercial-scale demonstration of a 5mW electrolyser (set for completion in April 2026) [7]. 

Biogas

Production of biogas also requires two ingredients: human sewage and electricity.

Human sewage: There is no shortage of human waste that could be used for the generation of biogas. It is estimated that households produce an average of 200-300L of wastewater per person per day. The advantage with biogas lies in the fact that a by-product of human waste is used as the fuel source, as opposed to using precious water. This by-product would otherwise need to be dealt with through a treatment process, but is instead used to generate a useful energy source.

Electricity: Existing technology for the extraction of biomethane from raw biogas has varying electricity requirements, depending on the manufacturer and scope of project. Using the Sydney Water/Jemena biomethane injection plant as an example, electricity requirements come in at 0.26kWh/kg biogas produced [8]. The biogas energy trade-off looks like this:

0.26kWh electricity INPUT = 6kWh biogas energy OUTPUT

 

Estimated financial cost of production

Hydrogen: According to NSW Government’s Hydrogen Strategy, green hydrogen costs AUD 0.72 per m3 to produce. Electricity currently makes up around 60-70% of this overall cost [9]. This may be seen as a cheap production cost; however, hydrogen’s poor heating value or energy potency must be considered. The path to lowering this production price literally hinges on a rapid downward trend of renewable energy costs [10] –   a trajectory that, under the current government’s energy policies and renewable energy rollout seems like wishful thinking.

Biogas: Due to the low electricity input required to generate biogas, costs associated with production are relatively low. A report from IRENA (International Renewable Energy Agency) estimates a cost of AUD 0.17 to 0.77 per cubic meter of methane for industrial waste-based biogas [11]. Biogas plants that are built at a wastewater treatment plant can also use a closed-loop energy supply, using the cogenerated energy from biogas to power the plant on a continuous basis such as with the Malabar Biomethane Injection Plant.

Plant and equipment requirements for production

Hydrogen: At present, electrolysers make up 30-40% of the overall cost of hydrogen production, the cost of electrolysers has been predicted to decrease as electrolyser production sees an uptick in the coming years [10]. As mentioned earlier, new electrolyser technology is under development by Australian company Hysata which should (maybe) contribute to the lowering cost of future plant and equipment.

Biogas: The Malabar Biomethane injection plant appears to be a success and should be used as the model to base other projects from. The project was completed by specialist company Enraque, who have performed many projects across Asia, Europe and the USA [12]. The Malabar project (pictured below) cost a total of $14 million to complete.

The Malabar Biomethane production plant

Infrastructure Requirements: Storage, transmission, and delivery

Hydrogen: At present, Australia’s existing gas pipelines are unsuitable for the transmission of 100% hydrogen gas. This is because the chemical properties of hydrogen can affect the material properties of steel pipework (ductility, toughness, and fatigue life). This effect is also known as ‘hydrogen embrittlement’ [13]. There is optimism that existing pipelines can be upgraded to allow for hydrogen transmission, but this has only been confirmed in theory and is yet to be demonstrated [14]. While it is optimistically estimated that the theoretical upgrades to gas networks would cost 10-20% of the total cost of building completely new networks, this is still a significant cost that must be considered [15], particularly against Biogas, which would require no such upgrades or alterations to the existing network. Currently, there are several states who are trialling the blending of hydrogen into the natural gas network. In South Australia, ‘Hydrogen Park’ (or ‘Hyp SA’ for short) currently delivers a 5% renewable gas blend to more than 4000 gas customers in Adelaide’s south. South Australia, Western Australia and Victoria envision a 10% blend by 2030. NSW is currently blending between 4-9% hydrogen into the gas network in Western Sydney. It should be kept in mind however that the lower heat value, or potency of hydrogen is much lower than our existing gas fuel sources. Even 100% hydrogen delivery only produces 28% of the energy given off by the same volume of natural gas. According to AGL, it would take 3.3m3 of hydrogen to match the energy output of 1m3 of natural gas [16]. It is unlikely that the end user will be charged less for this inferior gas blend, as it is extremely difficult to calculate what percentage of hydrogen may be in the consumer’s gas supply at any one time, and therefore what heat energy they will be getting out of that supply. According to the Australian Energy Market Commission (AEMC), “If the heating value is not accurately and frequently measured, the customer could be over billed for the amount of energy delivered” [17].

The question must therefore be asked, will investing billions of dollars to deliver 10% hydrogen into our gas network really result in more reliable, cheaper energy for all?

Gas Blends Table, which demonstrates the energy value decrease vs. hydrogen blend increase (AEMC)

Hydrogen has a high energy content by mass, but not by volume, which is a particular challenge for storage. To store sufficient quantities of hydrogen gas, it must; be compressed at 700 times normal atmospheric pressure, or refrigerated to minus 253 degrees Celsius [18]. This has serious transport and transmission costs and safety implications. Storing and handling hydrogen at such a low temperature that can result in cryogenic burns or lung damage. One alternate method of transporting hydrogen is converting it into ammonia (which can be stored at -33C and at normal atmospheric pressures). However, it would then need to be converted back to hydrogen. Each conversion, from water to hydrogen to ammonia to hydrogen results in energy loss [18].

To summarise what is a very complex discussion about the use of hydrogen at 100% or a blended capacity, the Public Interest Advocacy Centre (PIAC) had this to say in their consultation report to the Federal Government’s Climate Change Ministerial Council in November 2021:

Australia’s existing gas appliances and transmission networks are not built for hydrogen, and only able to accommodate very low-level blends at best. Some industrial processes cannot tolerate any hydrogen. To carry any significant amount of hydrogen would require expensive appliance replacement or upgrades and the overhaul of many safety standards and measures (such as smoke alarms) for every business and household using gas. Changes, replacements, and upgrades would be required throughout gas networks. These are significant considerations that go to the heart of the issue of long-term interests of energy consumers. [19].

Biogas: Once Biomethane has been extracted from raw biogas, there are no further changes that need to be made to inject it into the natural gas pipe network. In addition, biogas is “completely compatible with existing gas appliances and can be used in those manufacturing processes which currently rely on gas for heat.” [20]. This means that the there would be little to no upgrades or changes to existing natural gas infrastructure, in the home by domestic users, and in industry by commercial users.

Combustion Products/Emissions

Hydrogen: The biggest drawcard to hydrogen gas at present is when burned or used in a fuel cell, it produces no CO2 emissions. However, it must be noted that this is true regarding green hydrogen only, while each other type of hydrogen (blue, grey, brown/black) produces varying levels of emissions.

There has also been a recent influx in scientific research (such as the article for the Environmental Defense Fund, Ilissa B. Ocko and Steven P. Hamburg) claiming that hydrogen gas on its own, when released into the atmosphere can produce an increased amount of greenhouse gases which they claim can result in an atmospheric heating effect up to “100x more potent than CO2 emissions over a 10-year period”. At present, there is no way of quantifying the total amount of hydrogen released into the atmosphere. Leak-detection technology is available for large leaks, as this is considered by many stakeholders as important due to safety concerns. However, it appears that there is no technology yet available for small-leak detection, which would be critical to record and account for total hydrogen lost to the atmosphere.

Biogas: Although biogas has almost identical characteristics to natural gas, it produces fewer greenhouse gas emissions. This is because total emissions must be considered against the fact that they contribute a reduction to the greenhouse gas emissions, which would otherwise be created out of waste that decomposes naturally [5]. This is particularly advantageous as methane can be released, captured, and upgraded to biogas from other sources such as landfill sites, animal waste collection points, organic matter processing plant, and meat processing facilities (to name a few).

The ‘Bioenergy Roadmap’ produced in November 2021 for the Australian government estimates that biogas offers a 9% reduction in overall emissions (compared with 2019 levels) and a 6% reduction in the amount of waste sent to landfill (also compared with 2019 levels) [21]. Biogas is not perfect however, and produces emissions when released into the atmosphere as a gas, which consists mostly of methane.

Investments and Key Projects

Hydrogen: At present, there is a seemingly endless list of hydrogen projects either complete or underway. The CSIRO provides information on all projects using their hydrogen project database, ‘HyResource’ [22]. According to this database, “there are 108 hydrogen-related industry projects in Australia. 79 of these projects are in the development and planning phase, 16 are under construction, only 12 are currently in operation and just one has reached completion” [23]. There is also an abundance of funding provided from various government agencies, such as the recent $2 billion invested by the federal Government in the new ‘Hydrogen Headstart program’ [24]. A PwC analysis from 2022 estimated that the total investment required for all of these projects would be at least $250 billion [25].

Notable hydrogen projects:

Hydrogen Energy Supply Chain (HESC) Pilot Project – Victoria: Aiming to produce brown/black hydrogen, liquifying and transporting to Japan. Estimated cost: For the first project phase is $500 million, funded jointly by a group of Japanese companies, along with the Australian and Victorian governments [26].

Asian Renewable Energy Hub (AREH) – Western Australia: Aiming to produce green hydrogen and ammonia, with plans to become one of the world’s largest renewable energy projects. Estimated cost: $22 billion [27].

Western Green Energy Hub (WGEH) – Western Australia: Aiming to produce green hydrogen and ammonia. Estimated cost: $100 billion [28].

Western Sydney Green Hydrogen Hub – NSW: This is a pilot production facility producing green hydrogen that is injected into the natural gas infrastructure at a 4-9% hydrogen blend. Estimated cost: $15 million. [29].

HyP SA Hydrogen Park – South Australia: Aiming to produce green hydrogen and inject into the natural gas infrastructure at a 5% hydrogen blend. Estimated cost: $14.5 million [30].

Biogas

Malabar treatment plant (Jemena & Sydney Water) is the only commercial biomethane injection plant that has been completed at a large scale, however with the success of this project, future projects are expected to be undertaken.

However there are many biofuels-related projects that are either complete or underway in Australia. Some notable projects include:

Logan City Council Biosolids Gasification Facility – Queensland: This facility, completed in 2022 uses recycled heat to dry sewage sludge, and then produce a product called ‘biochar’, which is a soil-like material that is rich in nutrients and has agricultural and building industry applications. Estimated cost: $28 million [31].

Renergi biomass pyrolysis plant – Western Australia: This facility converts inedible plant material (called biomass) and municipal solid waste (garbage) into bio-oil (which can be used to fuel electricity generation or produce a renewable component of aviation fuel [32] and biochar [33]. Estimated cost: $9.8 million.

Kwinana Waste to Energy Project – Western Australia: This project (set for completion in Dec 2025) aims to collect non-recyclable waste, remove any recyclable materials, and burn the remainder which reduces the volume of the waste by up to 90%. The heat generated from this burn is used to produce steam, which can be used to generate electricity. Estimated cost: $696 million [34].

East Rockingham Waste to Energy – Queensland: This project (set for completion in December 2026) uses the exact process as the Kwinana Waste to energy project (above). Estimate cost: $510 million [35].

The Hazer Process – Western Australia: This is a demonstration project only (set for completion in September 2026) which aims to demonstrate a patented technology the aims to convert raw biogas produced from sewage treatment into hydrogen and graphite. Estimated cost: $22 million [36].

The Verdict

Hydrogen cannot be produced at a large enough scale to meet all of Australia’s energy and gas needs. Existing technology does not appear to be advanced enough to produce hydrogen gas or energy at a low cost, or a low energy input. Furthermore, the main resource required to produce hydrogen gas is water, a major potential obstacle in Australia.

There are encouraging developments being made in this space though, through pioneering companies such as Australian based startup Hysata, and their first-of-its-kind electrolyser. This electrolyser still needs to be demonstrated at scale though. There are several challenges that need to be overcome to achieve hydrogen gas usage and supply at a large scale, such as the volatility of hydrogen gas, energy losses along the production chain, incompatibility with existing gas infrastructure and appliances, and the upgrades required to our existing gas infrastructure due to the damaging effect of hydrogen embrittlement on steel pipework.

Hydrogen also has a low heating value (by volume) when compared to existing available gases (NG and LPG), with roughly three times as much supply required to produce the same amount of energy via natural gas.

Biogas also cannot be produced at a large enough scale to meet all of Australia’s energy and gas needs. It can however supplement them. Australia is in very advantageous position for the development of a biogas industry, with a strong existing gas industry, world class expertise, and high-quality natural gas network that could be utilised for the production and transport of biogas.

Biogas is also compatible with natural gas appliances which would require no investment from the end consumer to adapt and adopt the use of this energy source. Biogas appears cheap to produce, with a low energy input required. The main benefit in biogas, and other biomass energy projects is that it contributes to solving the ever-increasing waste problem that our world faces, by converting different forms of waste gas, and other waste products into energy and useful products. But there are also downsides, such as the risk of methane escaping to the atmosphere through leaks, venting and purging, and the low heating value in comparison to existing available gases (NG and LPG).

 

Summary

The future of renewable gas is promising. However, this pursuit should be done in a cautious manner, mixed with a dose of reality and healthy scepticism. In regard to the pursuit of and investment in renewable gases, the words of the  Public Interest Advocacy Centre ring true: “It must not come at the expense of consumers or with added risk to their efficient and affordable access to essential energy” [19].

While the benefits of renewable gases should be investigated, we should be honest with ourselves about the trade-offs and ask ourselves some hard but important questions:

♦ What are the negatives to renewable gases?

♦ Do the positives of renewable gases outweigh the negatives?

♦ Are there better energy options available, such as nuclear energy?

♦ How fast should we progress down the path of renewable gases? Gradually, or full speed ahead?

♦ Should we ban new connections of fossil fuel gases (NG & LPG) and mandate the use of renewable gases? or let the market innovate and consumers work out which gas is more reliable, efficient, cleaner, and more affordable?

♦ On what grounds are state governments and local councils imposing restrictions and bans on the use of natural gas?

 

References (HYDROGEN)

[1] – Hydrogen Tools: “Hydrogen Compared with Other Fuels”. Accessed 15/03/24.

[2] – Australian Renewable Energy Agency (ARENA): “Hydrogen energy”. Accessed 27/02/24.

[3] – CSIRO: Brown, F., & Roberts, D.: “Green, blue, brown: the colours of hydrogen explained”. 26 May 2021. Accessed 12/03/24.

[4] – GHD for Jemena Limited: “Malabar Biomethane Project Proof of Concept Life Cycle Assessment,” July 29, 2022. Accessed February 27, 2024.

[5] – International Energy Agency (IEA): “Outlook for biogas and Prospects for organic growth – World Energy Outlook Special Report on biomethane 2020,” p. 23. Accessed March 11, 2024.

[6] – Australian Renewable Energy Agency (ARENA): “Next steps for pioneering renewable hydrogen technology” Media Release 14/08/23. Accessed 27/02/24.

[7] – Australian Renewable Energy Agency (ARENA): “Hysata Capillary-fed’ Electrolyser Commercial-Scale Demonstration Project”. Accessed 27/02/24.

[8] – Eneraque: “Malabar Biomethane Injection Plant & Biogas Upgrading System.” No date given. Accessed February 27, 2024.

[9] – NSW Government: “NSW Government’s Hydrogen Strategy” (October 2021) – Page 23. Accessed 27/02/24.

[10] – NSW Government: “NSW Government’s Hydrogen Strategy” (October 2021) – Page 31. Accessed 27/02/24.

[11] – International Renewable Energy Agency (IRENA): “Biogas Cost Reductions to Boost Sustainable Transport,” March 6, 2017. Accessed February 28, 2024.

[12] – Eneraque:”Malabar Biogas Upgrading Plant Summary.” No date given. Accessed February 28, 2024.

[13] – APA: Parmelia Gas Pipeline – “Hydrogen Conversion Technical Feasibility Study Pg 3 (Background)” – May 2023. Accessed 06/03/24.

[14] – APA: Parmelia Gas Pipeline – “Testing confirms technical feasibility of converting gas transmission pipeline” – 19 May 2023. Accessed 07/03/24.

[15]– APA: Parmelia Gas Pipeline – “Hydrogen Conversion Technical Feasibility Study” – Public Knowledge Sharing Report May 2023.

[16] – Australian Gas Limited (AGL): “Extending the national gas regulatory framework to hydrogen blends and renewable gases” (pg 2) – 26/11/2021. Accessed 07/03/24.

[17] – Australian Gas Limited (AGL): “Consultation paper review into extending the regulatory frameworks to hydrogen and renewable gases” (pg 131) – 21/10/2021. Accessed 07/03/24.

[18] – ABC News, James Purtill: “What is green hydrogen, how is it made and will it be the fuel of the future?” – 23/01/2021. Accessed 07/03/24.

[19] – Public Interest Advocacy Group (PIAC): “Officials’ paper on amendments to the National Gas Law (NGL), the National Energy Retail Law (NERL) and Regulations,” October 26, 2021.

[20] – Energy Source and Distribution Magazine: “Biomethane enters gas grid in Australian first.” June 15, 2023. Accessed March 6, 2024.

[21]  – ENEA Consulting: “Australia’s Bioenergy Roadmap,” November 2021, Key Insights on p. 16. Accessed March 12, 2024.

[22] – CSIRO: “Hydrogen Map” (Completed in July 2022). Accessed 12/03/24.

[23] – Energy Magazine, Kody Cook: “Australia’s renewable hydrogen pilots and projects” – October 31, 2023. Accessed 12/03/24.

[24] – Department of Climate Change, Energy, Environment and Water: “Hydrogen Headstart program”. Accessed 12/03/24.

[25] – Australian Financial Review (AFR), Colin Packham: “Hydrogen investment in Australia tops $250b” – Mar 23, 2022. Accessed 12/03/24.

[26] – Hydrogen Energy Supply Chain (HESC): “About the Pilot”. Accessed 12/03/24.

[27] – Kimberley Development Commission, WA Government: “Asian Renewable Energy Hub”. Accessed 12/03/24.

[28] – Western Green Energy Hub (WGEH): “One of the world’s largest green energy projects”. Accessed 12/03/24.

[29] – ] CSIRO HyResource: “Western Sydney Green Gas Project” – March 15th, 2022. Accessed 12/03/24.

[30] – Australian Gas Infrastructure Group (AGIG): “Hydrogen Park South Australia”. Accessed 12/03/24.

[31] – Australian Renewables Energy Agency (ARENA): “Gasifier treats sewage, cuts carbon emissions, earns money,” September 12, 2022. Accessed March 12, 2024.

[32] – ARENA: “Renergi installs innovative biomass pyrolysis plant,” May 17, 2023. Accessed March 12, 2024.

[33] – ARENA: “Energy from Waste Through Pyrolysis,” June 9, 2023. Accessed March 12, 2024.

[34] – ARENA: “Kwinana Waste to Energy Project,” January 20, 2021. Accessed March 12, 2024.

[35] – ARENA: “East Rockingham Waste to Energy,” March 29, 2023. Accessed March 12, 2024.

[36] – ARENA: “The Hazer Process: Commercial Demonstration Plant,” May 3, 2022. Accessed March 12, 2024.