Electricity generation prospective of hydrogen derived from biogas using food waste in south-western Nigeria

Abstract

Hydrogen gas when produced from renewable energy sources and fed into fuel cells has the potential to produce energy in a sustainable manner. This present work estimates the electricity generation and environmental potentials of hydrogen produced from biogas. The biogas is produced in an anaerobic digester using the food component of the municipal solid waste collected from the selected cities in the South-Western Nigeria. The amount of hydrogen produced is determined using the stoichiometric chemical equations of biogas steam reforming process with water-gas shift reaction. The environmental benefit is estimated by considering ecological analysis of the system. The amount of fossil fuel that could be replaced by using the generated hydrogen gas for electricity production and the associated greenhouse gas emission that could be prevented are also evaluated. The results reveal that Lagos has the highest hydrogen generation potential of about 285 million kg (0.285 million tons) per year followed by Ibadan with 93 million kg (0.093 million tons) per year while the least production occurred in Osogbo. About 411 million kg (0.411 million tons) is produced from the reforming process in all the locations over the timeframe of 20 years (i.e., 2017–2036). This hydrogen production is equivalent to about 1.02% of the global hydrogen production in 2011 put at around 40.5 million tons. The total amount of hydrogen gas produced could generate about 19.46 million kWh of electricity per annum. An encouraging value of ecological efficiency of about 94.33% was achieved using hydrogen as source of energy. The results also show that a total of 7.446 million litres of diesel fuel could be replaced by hydrogen gas in the selected cities which is equivalent to 1.489 Billion Naira. The total amount of carbon dioxide and carbon monoxide emissions that could be avoided is about 16.031 million kg and 45.477 thousand kg. The sensitivity analysis showed that steam reforming efficiency and waste collection rate have positive correlation to hydrogen yield and electricity generation potential.