Following the successful commissioning of 20 EnviThan gas upgrading plants in China, Denmark, France, Germany and the UK, Germany-headed biogas plant operators and technology suppliers EnviTec Biogas AG now looks back on a successful five-year partnership with Evonik Fibres GmbH, an Austria-based technology leader for membrane-based gas separation and subsidiary of global speciality chemical major Evonik Industries AG.
As Evonik’s very first strategic partner, we are proud to have been a part of gas upgrading with SEPURAN Green from day one, so to speak – something that cannot be taken for granted in today’s market environment, said Olaf von Lehmden, CEO of EnviTec Biogas AG.
First deployed for carbon dioxide (CO2) separation at EnviTec’s pilot plant in Sachsendorf, the high-selectivity membranes are now well-established on the market – and the partnership with EnviTec has also gone from strength to strength.
Our shared experience over the last few years has generated a number of other successful projects, even outside Europe’s borders. In 2017, EnviTec was once again the leading consumer for our modules in the biogas industry, said Dr Goetz Baumgarten, Business Director Membranes within Evonik’s High-Performance Polymers division.
The partnership between the two companies began in October 2012 with the commissioning of the first EnviThan plant in Sachsendorf, Brandenburg. By the spring of 2013, two further gas upgrading plants with an output of 350 Nm³ had already been commissioned in Sachsendorf and Köckte in Saxony-Anhalt. This signalled the start of the commissioning of no less than 20 EnviThan plants, first in Europe and shortly afterwards in Asia – two new plants are now being built in France and Denmark.
Proprietary polymer
The three-stage membrane-based process for efficient gas separation patented by Evonik Fibres achieves a membrane yield of over 99 percent and makes the upgrading of biogas to biomethane significantly more cost- and energy-efficient.
The SEPURAN membranes are made from a high-performance plastic we developed in-house that has excellent pressure and temperature stability. This plastic gives the membranes their ability to distinguish precisely between methane and CO2, so methane can be obtained with a purity level of over 99 percent from the crude gas, explained Volker Wehber, Director SEPURAN Green in the Membranes business segment.
The modular design enables an existing plant to be expanded without major structural effort: this option has already been chosen many times by customers and successfully installed by EnviTec. One decisive benefit here is the minimal period of interruption for expansion work. With EnviThan plants, membranes can even be retrofitted with zero downtime for the system.
From grid injection to bio-CNG
Over the last five years, this innovative gas upgrading technology has seen a series of improvements. While all of the plants started by feeding biomethane into the existing natural gas grid, three plants are now manufacturing Compressed Natural Gas (bio-CNG) from biogas for the transport sector.
We see this particular application as a key driver in the move to sustainable transport in Germany. While we initially installed the membranes vertically, we ultimately switched over to a new, horizontal arrangement – and this is now the standard membrane design, said Stefan Laumann, biogas upgrading specialist at EnviTec.
By using this horizontal arrangement, EnviTec is now able to install almost three times as many modules in a single container. Currently, EnviTec is the only provider that also completes the fitting of Evonik membranes into their pressure housing.
Another change was introducing the option to source the feed-in compressor from EnviTec as well, said Laumann.
According to Laumann, this compressor boosts the pressure of the biomethane produced from around 12 bar to the network pressure required by the various destination gas networks. Progress has also been made in developing smaller, more compact plants: EnviTec now offers a single-container model for biogas plants up to 300 Nm³/h.
The new container design also provides dedicated space for up to two horizontal membrane racks: this is much more cost-effective since it not only avoids using a second container but also saves on the pipework, cabling and base.
