Life cycle assessment of GHG emission impacts when hydrogen is produced to fuel cell quality for Canadian light duty vehicles

Polymer electrolyte membrane fuel cell (PEMFC) performance is affected by impurities in hydrogen. Three common impurities of concern are CO, H 2S and NH3. Feedstock type and processing methods used for hydrogen production will impact the types and levels of impurities present in the final product. CO level is a key indicator for the quality of hydrogen fuel produced from fossil fuels. A review of hydrogen fuel quality requirements for PEMFCs, feedstock types, fuel processing methods and purification methods is presented. Three common methods for industrial scale hydrogen production (steam methane reformation (SMR), coal gasification and electrolysis) are discussed in terms of CO levels present in the final product. The life cycle assessment modeling tool, GHGenius, is used to assess GHG emissions associated with hydrogen production using SMR and electrolysis for various fuel grades. Changes to the GHGenius model are proposed to reflect associated greenhouse gas (GHG) emissions when production quality in terms of CO levels is increased. Life cycle assessment results for equivalent GHG emissions associated with hydrogen fuel production from SMR and electrolysis are presented on a well-to-tank basis and on a well-to-wheel basis for light duty vehicles (LDV) with ICEs and PEMFC vehicles. Results showed that PEMFC efficiency outweighed the increase in GHGs that result from higher quality fuel production. GHGs are reduced when PEMFC vehicles used a higher grade of hydrogen fuel when compared with emissions from an ICE that used a lower grade hydrogen fuel.