Biogas: an untapped energy source to avert a climate crisis?
By converting wastewater and other organic wastes into biogas, it could help to provide the electricity for 40 million people…
Reducing global greenhouse gas emissions
Adding anaerobic digestion (AD) treatment to centralised wastewater treatment facilities to generate biogas could help reduce global greenhouse gas (GHG) emissions by over 10 per cent.
Furthermore, the generated electricity could meet the needs of almost 40 million people globally.
That’s according to a new report from the Global Biogas Association (GBA) that set out to highlight the potential technology to generate renewable energy and recover nutrients.
One of the headline statistics from the report is that if used to generate electricity, biogas could meet up to 22 per cent of global electricity consumption.
By generating renewable energy in the form of biogas, the anaerobic treatment of organic wastes could collectively reduce GHG emissions by 3290 to 4360 metric tons of carbon dioxide equivalent (MTCO2 Eq.).
Reliable and regular feedstock
Regarding the anaerobic treatment of wastewater, the report said that electricity could meet the needs of between 27-38 million people, or the “natural gas needs of Ukraine”.
The GBA said that although the energy content of sewage sludge is low as compared to other feedstocks, it can be co-digested with food waste in urban settings when there is an established food waste collection process.
Sewage as a feedstock has the advantages that it is a steady and reliable stream, and the flow is guaranteed. Once the infrastructure has been set up, very little active intervention is required, the association said.
As populations and incomes grow and diets become more nutrient-dense, the nutrient recycling and energy generation potential of sewage sludge is expected to increase.
Biomethane progress across Europe
A by-product of the AD process, biogas can be converted using a combined heat and power (CHP) engine into either electricity or heat to help power wastewater utility operations.
The next stage is upgrading the biogas into a biomethane, or renewable natural gas (RGN) – this involves separating the carbon dioxide and methane contained within the biogas.
According to the WBA, if the potential biogas produced is upgraded to biomethane, it could meet between 26-37 per cent of global natural gas consumption.
However, the water sector continues to “find its feet in the biomethane-to-grid market”, said Global Water Intelligence (GWI) and that “potential financial returns” governed by the Renewable Heat Incentive (RHI) in the UK are encouraging utilities to give this process more consideration.
Although there existed 500 biomethane production facilities across Europe in 2016, only a small percentage used the sole feedstock of sewage sludge, GWI added.
Whereas Switzerland and the UK had 21 sludge biogas upgrading plants between them, this was a contrast to Germany where the majority of its plants are used for digesting energy crops.
“There is a tremendous potential for biogas to be a significant building block in the climate and energy plans for the UK, EU and the world... biogas has all the features of the next-generation technology,” said Niclas Svenningsen, manager of global climate action at UN Climate Change during the launch of the report.
He added: “It is a win-win-win-win-win industry: win for turning GHG into energy; win by using that energy to replace fossil fuels; win by turning global waste, that releases dangerous levels of methane gas every day, into a valuable resource; win by creating jobs and contributing to the new low-carbon economy; win by offering a stable energy source that can be built and used even at the household scale in remote areas.”
According to the GBA, the largest single emission source is by far energy production, causing some 70 per cent of global GHG emissions.
"Biogas needs to be at the table when the future policies of governments are designed when NDCs are reviewed and taken to the next level and other supporting measures, such as targets for banning food waste going to landfill, are set,” added Svenningsen. “This work needs to be conducted hand in hand; it needs to put together business, government and civil society.”
David Newman, president of the WBA, added that “we are still only scratching the surface of potential- we have developed just 2% of the industry’s long-term potential so far” and that “we need the policies to enable that now, above all by reducing and eliminating fossil fuel subsidies”.
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