Not just hot air: turning Sydney’s wastewater into green gas could be a climate boon



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Bernadette McCabe, University of Southern Queensland

Biomethane technology is no longer on the backburner in Australia after an announcement this week that gas from Sydney’s Malabar wastewater plant will be used to power up to 24,000 homes.

Biomethane, also known as renewable natural gas, is produced when bacteria break down organic material such as human waste.

The demonstration project is the first of its kind in Australia. But many may soon follow: New South Wales’ gas pipelines are reportedly close to more than 30,000 terajoules (TJs) of potential biogas, enough to supply 1.4 million homes.

Critics say the project will do little to dent Australia’s greenhouse emissions. But if deployed at scale, gas captured from wastewater can help decarbonise our gas grid and bolster energy supplies. The trial represents the chance to demonstrate an internationally proven technology on Australian soil.

pipeline at beach
The project would turn Sydney’s sewage into a renewable gas.
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What’s the project all about?

Biomethane is a clean form of biogas. Biogas is about 60% methane and 40% carbon dioxide (CO₂) and other contaminants. Turning biogas into biomethane requires technology that scrubs out the contaminants – a process called upgrading.

The resulting biomethane is 98% methane. While methane produces CO₂ when burned at the point of use, biomethane is considered “zero emissions” – it does not add to greenhouse gas emissions. This is because:

  • it captures methane produced from anaerobic digestion, in which microorganisms break down organic material. This methane would otherwise have been released to the atmosphere

  • it is used in place of fossil fuels, displacing those CO₂ emissions.

Biomethane can also produce negative emissions if the CO₂ produced from upgrading it is used in other processes, such as industry and manufacturing.

Biomethane is indistinguishable from natural gas, so can be used in existing gas infrastructure.




Read more:
Biogas: smells like a solution to our energy and waste problems


The Malabar project, in southeast Sydney, is a joint venture between gas infrastructure giant Jemena and utility company Sydney Water. The A$13.8 million trial is partly funded by the federal government’s Australian Renewable Energy Agency (ARENA).

Sydney Water, which runs the Malabar wastewater plant, will install gas-purifying equipment at the site. Biogas produced from sewage sludge will be cleaned and upgraded – removing contaminants such as CO₂ – then injected into Jemena’s gas pipelines.

Sydney Water will initially supply 95TJ of biomethane a year from early 2022, equivalent to the gas demand of about 13,300 homes. Production is expected to scale up to 200TJ a year.

Two women look over the Malabar plant
The project involves cleaning and upgrading biogas from the Malabar Wastewater Treatment Plant.
Sydney Water

Biomethane: the benefits and challenges for Australia

A report by the International Energy Agency earlier this year said biogas and biomethane could cover 20% of global natural gas demand while reducing greenhouse emissions.

As well as creating zero-emissions energy from wastewater, biomethane can be produced from waste created by agriculture and food production, and from methane released at landfill sites.

The industry is a potential economic opportunity for regional areas, and would generate skilled jobs in planning, engineering, operating and maintenance of biogas and biomethane plants.

Methane emitted from organic waste at facilities such as Malabar is 28 times more potent than CO₂. So using it to replace fossil-fuel natural gas is a win for the environment.




Read more:
Emissions of methane – a greenhouse gas far more potent than carbon dioxide – are rising dangerously


It’s also a win for Jemena, and all energy users. Many of Jemena’s gas customers, such as the City of Sydney, want to decarbonise their existing energy supplies. Some say they will stop using gas if renewable alternatives are not found. Jemena calculates losing these customers would lose it A$2.1 million each year by 2050, and ultimately, lead to higher costs for remaining customers.

The challenge for Australia will be the large scale roll out of biomethane. Historically, this phase has been a costly exercise for renewable technologies entering the market.

A woman cooking with gas
Biomethane will be injected into the existing gas network and delivered to homes.
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The global picture

Worldwide, the top biomethane-producers include Germany, the United Kingdom, Sweden, France and the United States.

The international market for biomethane is growing. Global clean energy policies, such as the European Green Deal, will help create extra demand for biomethane. The largest opportunities lie in the Asia-Pacific region, where natural gas consumption and imports have grown rapidly in recent years.

Australia is lagging behind the rest of the world on biomethane use. But more broadly, it does have a biogas sector, comprising than 240 plants associated with landfill gas power units and wastewater treatment.

In Australia, biogas is already used to produce electricity and heat. The step to grid injection is sensible, given the logistics of injecting biomethane into existing gas infrastructure works well overseas. But the industry needs government support.

Last year, a landmark report into biogas opportunities for Australia put potential production at 103 terawatt hours. This is equivalent to almost 9% of Australia’s total energy consumption, and comparable to current biogas production in Germany.

The distribution of reported operational biogas upgrading units in the IEA Bioenergy Task 37-member countries.

Current use of biogas in Australia.

A clean way to a gas-led recovery

While the scale of the Malabar project will only reduce emissions in a small way initially, the trial will bring renewable gas into the Australia’s renewable energy family. Industry group Bioenergy Australia is now working to ensure gas standards and specifications are understood, to safeguard its smooth and safe introduction into the energy mix.

The Morrison government has been spruiking a gas-led recovery from the COVID-19 recession, which it says would make energy more affordable for families and businesses and support jobs. Using greenhouse gases produced by wastewater in Australia’s biggest city is an important – and green – first step.




Read more:
‘A dose of reality’: Morrison government’s new $1.9 billion techno-fix for climate change is a small step


The Conversation


Bernadette McCabe, Professor and Principal Scientist, University of Southern Queensland

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Bioenergy: making money, and clean energy


Bernadette McCabe, University of Southern Queensland

The government’s draft direction this week to the Clean Energy Finance Corporation to invest in “emerging” clean energy over mature sources such as wind and rooftop solar has added yet more uncertainty to the renewable sector in Australia.

Bioenergy (renewable energy derived from plants or animals) is one such emerging technology. It currently makes up 7.9% of total clean energy generation, or about 1%, of Australia’s total energy generation.

From media reports to date it remains unclear whether technologies included under the bioenergy banner will be included in the investment mandate for “new and emerging technology”.

So what are the prospects for bioenergy?

Bioenergy’s popularity on the rise

The Clean Energy Council ranks bioenergy as Australia’s fourth-largest generator of renewables energy behind hydro, wind and solar.

Clearly bioenergy is getting bigger. As of September 2014 renewable energy projects in the CEFC pipeline are headed by bioenergy at 38%, well ahead of solar photovoltaics at 27% in second place.

The CEFC’s pipeline of projects.
http://www.cleanenergyfinancecorp.com.au/investments/our-pipeline.aspx

At a Bioenergy Australia business breakfast last month, the CEFC said it was considering A$800 million in investment in bioenergy to accelerate A$3 billion in projects.

While bioenergy is common and hugely popular in other parts of the world including Germany, the United States and China, it remains a relatively new technology in Australia.

Despite its relatively small scale, bioenergy has a nationwide footprint, with 139 plants across Australia in operation as of late 2014.

Sector attracts private, government investment

One of the key questions for financing clean energy is the return on investment. The CEFC’s contracted investments are currently expected to earn a portfolio weighted average yield of around 6% across their lifetime. How does bioenergy stack up?

The CEFC has forecast a 8.9% rate of return over six years for one New South Wales investment, while a Western Australian project is expected to return 8.2% over 10 years.

This figure relates to the debt component of the transaction and CEFC assumes the return on equity will be higher, giving a higher weighted average total return on the project.

While some of these bioenergy projects have been wholly funded by the businesses themselves, many have attracted funding from state and or federal government.

This funding has been granted because governments see the wisdom in underpinning investment in key businesses, some of which employ hundreds of people.

It has also come about because local, state and federal governments are concerned about the pressures of a growing population, waste accumulation and odour from landfill and industry.

Technologies active in alleviating waste problems

Bioenergy technologies such as biogas can be incorporated into existing operations to provide elegant solutions to turn waste into power, heat and other valuable by products such as fertiliser.

These technologies can be introduced in “closed-loop” systems and operate regardless of whether the sun is shining or the wind is blowing. The figure below shows the principles of a closed “carbon-loop” system.

The closed ‘carbon loop’ for bioenergy
http://www.resourcesandenergy.nsw.gov.au/energy-consumers/sustainable-energy/bioenergy

With CEFC funding of up to 50% in some cases, bioenergy is now in use in sectors which include meat processing at plants like Bindaree Beef at Inverell, piggeries, egg production and the garden products industry.

Australian bioenergy sources feedstocks from a number of sectors, including:

  • agricultural-related wastes like sugarcane residue (bagasse) and manure

  • municipal wastes including sewage and landfill

  • energy crops such as sorghum used to produce ethanol.

Bioenergy has the ability to literally swallow waste created by humans in municipalities, animals in intensive livestock operations, and crop production.

Outside the square is the biggest and longest-running user of bioenergy in Australia, the sugarcane industry.

For decades, selected mills in Queensland and NSW have been burning bagasse, the woody pulp left after sugar has been extracted from cane, to generate heat and electricity for use in in sugar processing, and selling surplus electricity to the grid.

The massive Integrated Food and Energy Developments project proposed for North Queensland includes sugarcane production incorporating steam and electricity production from bagasse. This could be a prime candidate for CEFC funding.

The Conversation

Bernadette McCabe is Associate Professor and Vice Chancellor’s Senior Research Fellow at University of Southern Queensland.

This article was originally published on The Conversation.
Read the original article.