6. Utilization of Agro-Waste as Carbon Source for Biohydrogen Production: Prospect and Challenges in Malaysia

Hydrogen gas (H₂) is a clean fuel and contained a relatively high energy density which is about 142 kJ g⁻¹. Recently, increasing attention has been given to the production of H₂ from biological route. The biological H₂ (biohydrogen) process is an H₂ production by microorganisms that utilize renewable energy resources as substrates. Possible biohydrogen production technologies include biophotolysis, photo-fermentation processes, and the dark fermentation route. Among these three production processes, the dark fermentation process is often regarded as the most potential route. It generates H₂ by utilizing carbohydrates as the carbon sources whereby glucose was found to be the most commonly used substrate. A high yield of biohydrogen, i.e., about 4 mol of H₂ per mole of glucose consumed can possibly be achieved through this route. Despite a reasonably high yield, industrial-grade glucose (35–50 USD per kg) is expensive and therefore, rendering the process less economical especially considering market value for H₂ typically ranging only between 3 and 5 USD per kg. Obviously, cheaper substrates are needed if dark fermentation process is ever to strive as the potential route for biohydrogen production. In Malaysia, abundance of agricultural waste is disposed into landfills annually and thus, making it free un-tap resources. This chapter reports the prospect and challenges of utilizing agro-waste as the carbon source for biohydrogen production in Malaysia. The work will provide basis evaluation on the potential of biohydrogen production where agro-waste is capitalized as main substrates for the process.