Biogas upgrading – Review of commercial technologies - SGC

SGC Rapport 2013:270
Using a filter with activated carbon to separate H2S before the PSA columns will
include a consumption of activated carbon for this separation. This demand is
however rather limited. Maintenance of a PSA-unit is usually planned to twice a
year, according to system producers.
Specific investment cost (€/Nm 3 /h)
3500
3000
2500
2000
1500
1000
500
0
0 500 1000
Capacity raw biogas (Nm
1500 2000
3 /h)
Figure 10 Specific investment cost for PSA upgrading units.
2.3 Membrane separation
This chapter has been written in cooperation between the authors and the companies
Air Liquide Medal, EnviTec Biogas, Evonik Fibres, MemfoACT AS and DMT
Environmental Technology that all are active within the area of biogas upgrading.
A membrane is a dense filter that can separate the components in a gas or a liquid
down to the molecular level. Membranes were used for landfill gas upgrading
already in the beginning of the 1990s in the USA (Petersson & Wellinger 2009).
These units were built with less selective membranes and a much lower recovery
demand for the methane. In most applications on the European market today, the
biomethane needs to have a methane concentration around 97-98% and the upgrading
process needs to have a methane recovery above 98%. Exceptions exist
in countries, e.g. the Netherlands and Germany, were L gas grids exist with lower
Wobbe index limitations.
To be able to combine high methane recovery with high methane concentration
requires, selective membranes and suitable design. One of the first unit of this
type was built in Bruck in Austria 2007 with membranes from Air Liquide Medal TM
and since then several more units with similar properties have been built in e.g.
Austria, Germany and France. In 2012, at least seven new units have been built
with membranes from various manufacturers such as Air Liquide Medal TM , Evonik
Sepuran® and MemfoACT AS.
The membranes used for biogas upgrading retain most of the methane while
most of the carbon dioxide permeate through the membrane, see Figure 11. This
results in biomethane that can be injected into the gas grid or used as vehicle fuel.
28 Svenskt Gastekniskt Center AB, Malmö – www.sgc.se