Anaerobic digestion (AD) has helped the water industry to manage waste better and be more energy efficient, making a renewable energy source available and enabling the industry to cut their carbon footprint.
The biogas generated from AD, comprising of a mixture of Carbon Dioxide (C02) and Methane, is not usually of an equable quality to natural gas. Hope is on the horizon, however, with the membrane-based gas processing systems now available, which result in a better quality of gas.
After biogas has been produced, this hollow fibre membrane technology separates the gasses, resulting in pure Methane of sufficient quality to be injected directly into the gas grid or used as a biofuel. The Methane yield is so high it is in excess of 99% if Evonik’s patented 3 stage membrane process is applied.
Whilst options for putting the separated CO2 to good use are also being explored in the form of liquid fuels and industrial chemicals, for example.
The Biomethane itself can be liquified and used as liquid fuel and industrial chemical building block. The CO2 can be used in the food and beverage industry or in gaseous form to grow plants in a nearby greenhouse.
Embracing renewable energy
Evonik’s hollow fibre membrane technology SEPURAN® Green is one such system, which purifies the gasses so they can be utilised more efficiently.
Available on the market for just seven years, such is its success that it’s already been installed at around 240 sites across the globe. Meaning waste at these locations is being put to good use, producing renewable energy with the same quality as natural gas.
As a leading speciality chemical company, operating in over 100 countries around the world, Evonik’s expertise encompasses developing customised energy solutions for a diverse range of industries.
What speaks volumes about this state of the art technology, is that Evonik is utilising it themselves, thereby reducing their dependency on fossil fuels, assisting in fuelling their plants and running their vehicle fleet too.
SUEZ, the French Water Agency, has used Evonik’s biogas upgrading membranes to convert its sewage sludge treatment plant, located in Sormiou quarry, to launch the biggest biomethane production project ever seen in France.
Whilst in the Netherlands, Delfland Water Authority utilised Evonik’s membranes in their new biogas upgrading unit at its ‘De Groote Lucht’ wastewater treatment plant, which is now producing 1 million Nm3 biomethane fed directly into the national gas grid, as opposed to 1.8 million Nm3 of biogas annually.
Optimising resources better
With UK water companies under immense pressure to achieve more with fewer resources and to reduce their impact on the environment, this membrane technology may prove a means by which they can become more sustainable and use their resources better.
Traditionally, biogas is used as raw gas to produce heat and electricity on site, but given it is produced 24/7 there isn’t always an immediate use for the electricity generated.
Membrane technology SEPURAN® Green, not only enables biogas to be upgraded, but also to be stored in the site’s pipeline infrastructure, so the gas can be extracted when it is required.
Membrane technology benefits
Evonik’s SEPURAN® Green has a number of additional benefits too. The modular set up is extremely flexible, meaning it can be used on a wide range of sites in installations of all sizes.
The fact that the membrane technology can be added to over time, future-proofs the system too, so it can be adjusted, depending on the site’s needs.
Cost effective, the system doesn’t require any other chemicals, water or resources to operate, so it is simple and efficient to use, as well as being environmentally friendly. The simple set up, moreover, means the operation is straightforward too.
Fitting into the landscape well, it is containerised and aesthetically speaking, doesn’t look like a chemical plant. Set up mostly offsite, the SEPURAN® Green system is installed quickly and easily, minimising the amount of labour needed and the downtime required onsite while it is installed.
Meeting the challenges ahead
The UK water industry is under enormous pressure to be more energy efficient, utilising sustainable energy sources with cleaner emissions wherever possible. Evonik’s SEPURAN® Green system is one step on the road to making the industry more sustainable, helping to create a circular economy in which no waste is wasted.
www.sepuran-green.com
