Feasibility Study of a Fossile Fueled Zero Emission Vehicle 2012-01-1650

This study investigates the technical feasibility of onboard carbon capture in vehicles. In fact there are two different main concepts of hybrid electric vehicles with batteries and range extenders proposed. The first concept uses an Internal Combustion Engine as range extender. Carbon dioxide is separated from the flue gas of this Internal Combustion Engine by chemical or physical absorption. In the second concept a solid oxide fuel cell (SOFC) is used as a range extender. The CO remaining in the anode exhaust gas is not combusted as usual by mixing anode and cathode exhaust gases but shifted with water vapor, sufficient available in the anode exhaust gas flow, to H₂ and CO₂. The H₂ is separated by a membrane permeable only for H₂ and recycled by the methane flow to the SOFC stack. Carbon dioxide can then be separated by simply condensing the water vapor of the anode exhaust gas of the SOFC.

Carbon dioxide can either remain onboard chemically bonded, e.g., as carbonate with the absorption media or stored in a pressure vessel after desorption or condensation of the water vapor. As one mole methane produces one mole CO₂, the CO₂ can be stored in one chamber of a double chamber tank. The tank is, e.g., divided into two chambers with variable volume by a non-permeable but flexible membrane; on the other side of this membrane methane is stored. At the gasoline station the empty methane chamber is filled with new methane and the CO₂ is discharged simultaneously providing also simple fueling and CO₂ removal methods. Carbonate can also be disposed at the gasoline station and calcinated in centralized plants, i.e., CO₂ can be separated and CaO reused.

Furthermore all concepts are compared in fuel efficiency and general feasibility. The SOFC concept seems to be the most attractive one, because it shows the highest efficiency, uses the simplest CO₂ capture concept and releases the captured CO₂ in gaseous state, providing the simplest CO₂ discharging method.