Renewable Gas Terminology

Anaerobic digestion

A process which breaks down organic matter in an oxygen-free environment to produce biogas.

Biogas

Gas resulting from the breakdown of organic matter in agricultural waste, wastewater, food waste and in landfill. It is generally produced through the process of anaerobic digestion. It is considered renewable because its source – organic waste – is continually replenished.

The carbon emissions from the use of biogas are biogenic.

Biogenic

Produced or brought about by living organisms. Biogenic carbon emissions are those related to the natural carbon cycle. When released into the environment (eg when biomethane is combusted), they are not considered to increase the concentration of carbon in the atmosphere, because they are releasing what has previously been absorbed. This contrasts to fossil fuels which release carbon stored millions of years ago when used, effectively increasing the concentration of carbon in the atmosphere.

Biomethane

A form of renewable gas, sometimes called renewable natural gas. Biomethane is methane produced from biogas. The biogas is purified or ‘upgraded’ to biomethane by removing carbon and impurities to meet the Australian Standard for general purpose natural gas (AS4564:2020). As such, it is entirely substitutable for natural gas and compatible with existing gas network infrastructure and household appliances.

Biomethane, when combusted, is considered carbon neutral because the carbon released is biogenic.

When taking into account the full ‘cradle-to-grave’ life-cycle of biomethane, there may be some emissions associated with, for example, its production and transportation. At our Malabar Biomethane Injection Plant the energy used to produce biomethane is offset through the purchase of large-scale generation certificates (LGCs). However, there is a small amount of fugitive methane emissions that may occur during transportation though the network. This is why we refer to biomethane from Malabar as low emission.

Malabar is the first certified renewable gas facility registered under the GreenPower® certification scheme.

Blending

In the context of renewable gas, hydrogen is blended or mixed with natural gas for use in the gas network.

Currently, hydrogen must be blended because it needs to be transported under higher pressure. In transitioning towards using hydrogen within gas networks, network operators are currently blending small amounts of hydrogen, as the current network and appliances are not hydrogen capable. Around the world, blends of up to 10 per cent hydrogen are being used without compromising or modifying existing gas networks and research continues in this area to increase our understanding of what is required to achieve higher blends (see for instance Future Fuels CRC research in this area).

Carbon cycle

Carbon constantly moves between the atmosphere and living organisms in water and on land.

Carbon neutral

Making or resulting in no net increase of carbon emissions into the atmosphere.

Biomethane is considered carbon neutral when combusted because the carbon that is released is biogenic.

Certified renewable gas

Gas that is certified renewable under an independent certification or verification scheme such as GreenPower®.

Circular economy

An economy in which the life cycle of a product is extended and attributed value for as long as possible by repurposing or reusing it in alternative ways. This includes adopting regenerative design principles and extracting value from “waste”.

Biomethane is a good example of the circular economy as it puts organic waste to valuable use.

Decarbonisation

The act of decreasing net carbon emissions

Energy transition

The energy transition refers to the global shift from fossil-based energy production and consumption to low-emission energy sources, in an effort to reduce greenhouse gas emissions and mitigate climate change. The transition - driven by community expectations and government emission reduction policies - depends on global action to accelerate the decarbonisation of the energy sector to achieve a climate-safe future in line with the goals of the Paris Agreement. At Jemena, we are supporting a fair and equitable energy transition for customers as we move towards net zero emissions, and believe that renewable gas has an important role to play in ensuring an orderly and low-cost transition to net zero emissions.

Fossil fuels

Hydrocarbons used as fuel like oil, natural gas and coal which are made of fossilised plant and animal remnants from millions of years ago, typically buried deep in the ground.

When combusted fossil fuels release the carbon that has been stored for millions of years, effectively increasing the concentration of carbon in the atmosphere.

Greenhouse gases

Gases - such as carbon dioxide (CO₂ ), methane (CH₄ ) and nitrous oxide (N₂O) - the increasing emission of which into the atmosphere, primarily from the use of fossil fuels, drives climate change.

GreenPower®

Government scheme for the accreditation of renewable energy. GreenPower has established a pilot Renewable Gas Certification Scheme which provides independent verification of the attributes of renewable gas.

Hydrogen

Hydrogen (H₂) is the most abundant element in the universe. When used, hydrogen does not release any carbon or other greenhouse gas emissions.

Hydrogen gas can be used as a substitute for natural gas in various industrial uses, including for heating, power production and as feedstock (for example, it is currently used in ammonia production).

Currently, hydrogen must be blended before use in Jemena’s gas network or with current household appliances.

Hydrogen-capable*

Systems or networks capable of transporting 100% hydrogen safely.

Hydrogen-compatible*

Materials that can be safely used with 100% hydrogen.

Large-scale generation certificates or LGCs

A form of renewable energy certificate created by large scale renewable energy projects under the Renewable Energy Target scheme.

Low-carbon

Not adding more or minimising the amount of carbon emissions that contribute to the concentration of greenhouse gases in our atmosphere.

Low-emission

Not adding more or minimising the amount of greenhouse gas emissions that contribute to the concentration of greenhouse gases in our atmosphere.

Methane

Methane (CH₄) is the main constituent of natural gas and is considered a greenhouse gas.

Net-zero emissions

Describes an overall balance between greenhouse gas emissions produced and taken out of the atmosphere.

Natural gas

Natural gas is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane. Natural gas is a fossil fuel because it was formed when layers of organic matter decomposed and were subjected to intense heat and pressure underground over millions of years.

Offset

An ‘offset’ is a reduction, displacement or removal of carbon or other greenhouse gas emissions that is used to compensate for emissions made elsewhere.

Purchased renewable electricity

Renewable electricity that is purchased from a retailer through its offset program, such as GreenPower®.

Power purchase agreement

An agreement to invest in and purchase the output from a renewable energy project.

Renewable electricity

Electricity produced from renewable sources like the sun, wind, water or waste. Renewable electricity may be generated directly from a renewable energy system, sourced from a large renewable energy project through a power purchase agreement or purchased renewable electricity from a retailer.

Renewable gas

An umbrella term for gases produced using resources that are continually replenished. Types of renewable gases include biomethane and renewable hydrogen.

Renewable hydrogen

Hydrogen produced through electrolysis, separating water into hydrogen and oxygen molecules, using renewable electricity.

Renewable natural gas

Another term for biomethane.