Absorption - Introduction to Carbon Capture and Sequestration - page 205

Section 5
Costs of absorption
When we talk about achieving the widespread adoption of absorption
techniques for carbon capture, we always have to go back to the issue
of money. Costs are a signifi cant barrier to the deployment of carbon
capture. As we mentioned at the very beginning of this unit, it's possible
to go out right now and order an absorber and stripper from “Absorbers-
R-Us.” The problem is that the energy costs associated with the technol-
ogy are steep. In the design of an absorber, it's important to keep both
capital and maintenance costs of the technology in mind.
Let's start with the capital costs. The price of the chemicals and bio-
solvents involved in absorption are an important part of the cost equa-
tion. Earlier we touched on the immense volume of pure water solvent
(200,000 gallons per second) that would be needed to process the
exhaust from a standard 500 MW coal-fi red power plant. Ideally, a sol-
vent or additive should be cheap, synthesizable, and easily regenerated
(in addition to being good at taking up CO 2 ). Aside from the solvent
costs, we have to consider the capital costs of building the equipment:
the absorption tower and plates.
The operating and maintenance costs of absorption (compression,
pumping, heating and regeneration of solvent) are particularly signifi cant
sources of expense, and a big part of the challenge with CO 2 absorption.
There is not a cheap way to perform these functions right now, and most
of the breakthroughs associated with lowering these costs have to do
with novel ways to siphon energy from existing sources for “free.” In
other words, it would be a major innovation if our absorbers could siphon
off waste heat, say from a power plant. This is an area of CCS research
that we hope will continue to develop.
Cost is a factor that can put stress on the relationship between the
energy industry and CCS research. Imagine that you are in charge of a
large department of energy research, and in this program your team
needs to develop a new absorbent. Let's say there is the possibility of
making new types of materials. You decide to ask your team what a sen-
sible target would be for your project, and you get drastically different
answers. Your chemist wants the best absorbent to be the one with the