Maximising CO² recovery to drive developments in biogas utilisation
11 April 2017
Pentair Haffman's biogas upgrading system with CO2 tank
With Ireland currently working towards its European Union (EU) 2020 targets using a combination of wind and solar technologies, Pentairs’s Ivan Rigney believes the generation of biogas through anaerobic digestion could be the crucial missing piece of the renewables jigsaw.
By 2020, the EU has mandated that the target for greenhouse gas emission reductions is 20 per cent relative to emissions in 1990. A 20 per cent share for renewable energy sources in EU energy consumed and 20 per cent savings in energy consumption compared to projections are also expected.
“What is interesting about the Irish environment is that, in chasing the 2020 targets and looking at renewables, we’ve focused extensively on wind power and generating electricity,” said Rigney, director at Pentair Ireland Ltd., before highlighting the role of solar energy.
“The other area where there has been a focus is solar energy. Due to improvements in photovoltaic technology there have been incentives, both on the electricity generated from wind turbines, but also now from solar power. One piece that has not been put in place – one final piece of the jigsaw – is biogas and the generation of biogas through anaerobic digestion [AD].”
“Generating biogas from AD is a fabulous system in terms of generating green energy, where and when you want it. This is because we can utilise feedstock that can be grown through our unused agricultural land or through optimising the grasslands that we currently have. It’s possible to find the feedstock for our AD plants in the pasture land that we have at the moment and also meet our commitments on beef and on dairy,” explained Rigney, “not to mention food waste which can be converted to valuable energy in an environmentally friendly manner.”
Developing the biogas upgrading market
The biogas upgrading market is in its infancy. Up until 2010, less than 100 upgrading installations had been built in Europe. By 2014, this number had increased to more than 300 installations. It is expected that the biogas upgrading market will see moderate growth through to 2021, followed by sustained growth between 2022 and 2030.
Up until 2013, almost 14,000 biogas-to-electricity plants were built – the majority in Germany. This number is expected to double in line with the EU mandate. So what is driving developments in biogas utilisation?
One factor is that subsidies on producing electricity are being scaled back while subsidies on producing biomethane are being increased. Biomethane is also flexible in that it allows for storage of energy it generates while also having the added advantage of being weather independent. Methane has a higher caloric value when compared to electricity due to its higher energy usage potential and it also has a higher saleable value when sold as fuel.
“This is a very, very exciting market that needs to be developed over the next number of years. Through the feedstocks mentioned earlier and through waste materials – food waste, slurries, poultry manure – you can generate high volumes of green gas,” said Rigney.
Biogas produced through AD consists of roughly 55 per cent methane and 45 per cent CO². With conventional biogas upgrading techniques, the CO² by-product and with it a notable amount of methane is expelled into the air and is lost. This means unnecessary economic loss.
Pentair’s CO² recovery systems allow plant operators to recover the CO² from the biogas stream, which minimises the plant’s overall CO² footprint. As the produced CO² complies with EIGA (European Industrial Gases Association) specifications, this provides the operator with an additional (and extremely lucrative) revenue stream through the sale of liquefied CO² to third parties.
“The green gas is generated, what we would describe as raw biogas, and this product can be upgraded to purified biomethane. This can then be used either as compressed natural gas for transportation – in other words fuel for vehicles such as hauliers, trucks and lorries.”
Benefits of producing green energy from green gas
“Alternatively, it can go straight on to the national gas grid. The 45 per cent which is CO² is effectively the ‘carbon footprint’ of the system and can be recovered, purified to food grade and can then go into a wide range of applications in food and drink, or industrial applications, everything from dry ice, cooling systems, to PH correction, water treatment plants and much more. It has an endless number of applications.
“This means that a bio gas plant gives you the benefit of producing green energy, producing CO² – a valuable gas that provides another revenue stream – and it also offers you the carbon credits on the feedstock.
“The market is now looking at introducing green gas certificates which can be traded. This means that if you inject into the grid your upgraded biomethane, a large industrial customer who has renewable energy requirements can buy the gas from you. By buying a certificate, they can prove that the purchased gas is green and therefore from a renewable source. So the whole supply chain from generation to end user is completely linked,” concluded Rigney.
Rigney adds: “What’s more, biogas production can me modulated to meet demand as it ebbs & flows through the natural cycle of the countries seasonal energy requirements, this is a truly unique and highly attractive dimension to biogas upgrading technology versus wind & solar.”
Earlier this year, Pentair completed the acquisition of Union Engineering, a company that specialises in sustainable technologies for capturing, recovering and purification of carbon dioxide. Speaking at the announcement of the acquisition, Daniel Stripe, Pentair vice president of process technologies, reiterated the company’s commitment to building a more sustainable world.
“Reducing carbon dioxide emissions and utilising renewable energy sources are global challenges which Pentair addresses with its carbon dioxide capture and reuse and biogas upgrading solutions,” said Stripe.
Pentair plc delivers industry-leading products, services and solutions for its customers’ diverse needs in water and other fluids, thermal management and equipment protection. With 2015 revenues of $6.4 billion, Pentair employs approximately 30,000 people worldwide.
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