Vehicular CO2 emissions slashed with onboard capture and conversion scheme
S. Himmelstein | December 26, 2019A system based on temperature swing adsorption technology has been engineered at École Polytechnique Fédérale de Lausanne, Switzerland, to slash carbon dioxide emissions from internal combustion engine-powered vehicles by 90%. The gas captured from the exhaust stream is liquefied and stored within the vehicle for future use as feedstock to produce gas or liquid green fuels and chemicals.
Flue gases in the exhaust pipe are first cooled down and the water is separated out, after which CO2 is isolated with a temperature swing adsorption system using a metal-organic framework adsorbent. Once saturated with CO2, the material is heated to effect extraction and compression of pure CO2 with high speed turbocompressors, resulting in liquefaction of the gas. Waste heat available in the exhaust stream is converted into mechanical power via Rankine cycle technology to drive the heat pump compressor and product compressors.
Overview of CO2 capture system design: integration of Rankine cycle (RC) and heat pump (HP). Source: Sharma and Maréchal
The processing equipment is housed within a capsule measuring 2 m x 0.9 m x 1.2 m, placed above the driver’s cabin. A truck consuming 1 kg of conventional fuel could produce 3 kg of liquid CO2 without incurring any energy penalty.
The system can be retrofitted to all trucks, buses and boats, and can operate with any type of fuel to offer significant pollutant emissions reductions and renewable fuel benefits.
"...a truck consuming 1 kg of conventional fuel could produce 3 kg of liquid CO2 without incurring any energy penalty."
This is difficult to believe. How is this possible?
In reply to #1
The chemical formula of fuel is approximately CH2 (that is chains and rings of carbon atoms, each with 2 hydrogens). The molecular mass of each carbon unit is 14.
The molecular mass of CO2 is 44. The carbon has gained mass by combining with oxygen from the air to make CO2. Simple chemistry.
In reply to #2
Perhaps I should have made my statement more difficult to misunderstand. It is not the mass of the reactant or resultant that I find difficult to believe. What is difficult to believe is the part about not incurring an energy penalty.
The idea that there would be no energy penalty for producing CO2 as a high pressure liquid vs. just exhausting it to atmosphere is difficult to believe.
Simple thermodynamics.