Ammonia is widely used as a fertilizer, a cleaner, a building block for pharmaceutical and other products, and can be used as fuel for fuel cells or internal combustion engines. Ammonia's vaporization properties also enable its use as a refrigerant. But ammonia must be stored as a liquid under mild pressure or at low temperature, and both refrigeration and ammonia storage require compression. Conventional mechanical ammonia compressor technology is only 65% efficient and is reaching its limits due to heat transfer and manufacturing limits. A new, electrochemical method to compress ammonia could lead to significant energy savings through increased efficiency.
Project Innovation + Advantages:
The University of Maryland (UMD) will develop an electrochemical compression technology for ammonia. Electrochemical (an alternative to mechanical) compression has rarely been considered for ammonia, and the UMD team seeks to develop a new method to raise the compression efficiency from its current rate of 65% to the long term goal of up to 90%. If successful, replacing mechanical ammonia compression processes with electrochemical ones could save up to 10% of electricity consumed by commercial buildings while eliminating related carbon emissions and saving up to $3.5 billion annually for the United States. Using UMD's method, ammonia is electrochemically compressed using a proton exchange membrane electrochemical cell with hydrogen as a carrier gas. Unlike mechanical compression, the team's electrochemical device has no moving parts or lubrication oil and does not produce any noise. The successful demonstration of electrochemical ammonia compression will stimulate more research on the transfer of not only ammonia but other fluids using similar approaches, as well as the exploration of ion exchange membranes for other types of electrochemical gas transfer. The technical goal of Maryland's research is the construction and evaluation of a 50 W electrochemical compression stack that can compress ammonia from 1 atm to 10 atm in a single step with an ammonia flow rate of 0.045 g/s and a compression efficiency of over 70%.