08-03-2009 CCS vil øge USAs kulforbrug med 390-600 mill. tons om året

I en artikel publiceret januar 2009: The energy penalty of post-combustion CO2 capture & storage and its implications for retrofitting the U.S. installed base (Kurt Zenz House, Charles F. Harvey, Michael J. Aziz and Daniel P. Schrag) konkluderer forfatterne, at forbruget af kul i forbindelse med at kompensere for 80% af CCS-relateret merenergiforbrug på kulkraftværker er i størrelsesordenen 390-600 mill. tons om året. Dette svarer til et merenergiforbrug på 42-65%.

Introduction

In 2006, [Pulverized Coal] plants composed about 70% of U.S. fossil-fuel derived electricity and about 50% of total electricity production.5 To produce that electricity, the plants burned 930 million tonnes of coal and produced 1.9 gigatonnes (Gt) of CO2, about 1/3 of total U.S. emissions. In addition, PC power constitutes well over 90% of coal-fired power in the world.

Conclusion

Achieving substantial reductions in CO2 emissions requires
either shutting down a large fraction of the current installed base
of coal-fired power plants or retrofitting those plants for CCS.
Previous studies have estimated that the additional fuel required
(f2) to maintain constant work output for a PC retrofit is between
50% and 80%. An analysis of the thermodynamic limit indicates
those values might be improved by harnessing more of the
available waste heat and by improving the 2nd-law efficiency of
temperature-swing separation systems. It appears difficult,
however, to improve f2 for post-combustion capture to below
25% in practice.

Our most likely efficiency scenario indicates
that offsetting the energy penalty incurred from capturing
and storing 80% of the U.S. coal fleet’s CO2 emissions will
require either an additional 390–600 million tonnes of coal, an
additional 69–92 gigawatts of CO2-free-baseload power, or
a 15%–20% reduction in overall electricity use.

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