Chapter 3G - Fuel Cell Challenges & Innovations

Raw material used for producing another product

Set of 12 principles aimed at reducing the use or production of harmful substances in chemical processes

Can be produced at a rate that is greater than or equal to the rate of consumption without compromising future generations

• proportion of chemical energy in the fuel consumed that is converted to electrical energy (usable energy) • sources of inefficiency include heat loss/obstruction of current

• electrodes coated w/ catalysts to increase reaction rate • reduces amount of time for energy to escape system & be lost to the atmosphere • increases energy efficiency • most effective catalysts are non-renewable & expensive

• porous electrodes allows diffusion of gaseous reactants • smaller & more numerous pores = greater surface area • increases contact b/w reactants/catalysts increasing efficiency • development of nanomaterials as electrodes

• heat (by-product) of fuel cell is captured & used to heat cars/buildings • increases energy efficiency

• combine fuel cell w/ another system • allows an excess energy from fuel cell when energy demand is low to be stored • minimises energy loss

• maximises speed of ion movement • increases current efficiency • more resistant to temperature changes • prevent leakages/ possible contamination • polymer electrolytes can be expensive to produce & are derived from crude oil

• high temperatures/pressures increase rate of reactions thus efficiency • maintaining high temperatures requires large energy amounts • decreases net energy efficiency of fuel cell • heat produced is often used to heat system

• increasing the lifespan of a fuel cell (currently 5 years) by using more durable materials will increase long-term efficiency

• use of renewable feedstocks e.g. biofuels/green hydrogen, can increase sustainability • CO₂/H₂ fuel cell • bioethanol fuel cell • microbial fuel cell

• fuel = H₂(g) (can be renewable) • CO₂ used instead of O₂ • CO₂ considered renewable as product of cellular respiration & combustion of biomass • removes CO₂ from atmosphere • designed to maximise efficiency (PEM, C nanomaterials, platinum catalyst

Bioethanol is the fuel (a renewable biofuel produced from corn & sugarcane crops)

• bacteria uses enzymes to speed up oxidation of renewable plant-based fuels e.g. glucose • any organic feedstock that can be broken down by bacteria e.g. wastewater/compost can be used as fuel • clean water by-product of microbial wastewater treatment fuel cells

• not neccersarily sustainable

• edible crops e.g. corn, wheat • intensive farming required to meet demand, potentially damaging soil • competes with valuable food sources

• non-food crops & waste materials e.g. grasses/household waste • waste is readily available • difficult to convert biomass to conventionally usable fuels

• algae & other microbes • high productivity & potential to absorb CO₂ from atmosphere • difficult to process to match energy demand

• cyanobacteria • high productivity & potential to absorb CO₂ from atmosphere • difficult to process to match energy demand