New membranes reduce CO2 emissions from power stations
CO2 emissions six times lower with newly developed membranes
18 March 2010
Carbon dioxide (CO2) is a major cause of global warming. Power stations in particular emit large quantities of CO2: 60% of total emissions. Sander Reijerkerk of the University of Twente has developed two new membranes that filter out CO2 emissions. Both of the membranes can bring about a six-fold reduction in CO2 emissions. Reijerkerk will receive his PhD from the faculty of Science and Technology on 19 March.
The majority of electricity is generated using fossil fuels in
power stations. When these fuels are burned a mixture of nitrogen,
water vapour and carbon dioxide (CO2) remains, with the
CO2 causing the most environmental problems. Sixty
percent of total CO2 emissions are from power stations.
Sander Reijerkerk of the University of Twente has developed two new
membranes that can filter out these CO2 emissions. The
advantage of using membranes over other methods, such as absorption
or cryogenic distillation, is that they are energy-efficient and
also modular, and therefore easy to install one after the
other.
The University of Twente PhD student was confronted with two
problems: the large amounts of emissions from power stations and
the relatively low concentration of CO2 in those (10 to
15 % of the total). There was therefore a need for membranes that
could allow large amounts of CO2 to pass through them.
Reijerkerk developed two different membranes that both allow large
amounts of CO2 to pass through, but at the same time are
not highly permeable for most other gases. His work was based on
the use of so-called multi-block copolymers. These rubber-like
polymers were already being used to separate CO2 from
other gases, but they were not yet permeable enough for the
economically viable separation of CO2 from nitrogen at
power stations.
A multi-block copolymer is made up of soft CO2-permeable
segments in combination with hard non-CO2-permeable
segments that give them their mechanical strength.
Figure 1. A multi-block copolymer. The red blocks are not
CO2-permeable, while the black lines are.
Reijerkerk therefore investigated strategies to influence and
direct the properties of multi-block copolymers, and so improve the
overall performance of the membranes. In the first strategy he
adapted the polymer at the molecular level in such a way that it is
six times better at separating CO2 from the other gases.
In the second strategy he added an additive to a commercially
available multi-block copolymer, so that here too the
CO2 permeability rose by a factor of six. The
researchers expect that a combination of these two strategies will
lead to even higher permeability. This research is a first step
towards reducing CO2 emissions by filtering them out
with special membranes.
Figure 2. A visual representation of strategy 1. Adapting the
polymer at the molecular level creates larger surfaces to filter
out the CO2 (compare figure a with b).
Note to editors:
Sander Reijerkerk will obtain his doctorate from the Faculty of
Science and Technology on 19 March. He carried out his research at
the Membrane Technology department and the IMPACT research
institute. His tutors were Prof. Matthias Wessling and Dr Kitty
Nijmeijer. His thesis 'Polyether based block copolymer membranes
for CO2 separation' is available in digital form on
request.
Contact person for the press: Rianne Wanders,
053-4892721 or 06-10497231.
