Challenges and Opportunities for Hydrogen Production from Microalgae

The global population is predicted to increase from ~7.3 billion to over 9 billion people by 2050.Together with rising economic growth, this is forecast to result in a 50% increase in fueldemand, which will have to be met while reducing carbon dioxide (CO 2 ) emissions by 50–80%to maintain social, political, energy and climate security. This tension between rising fuel demandand the requirement for rapid global decarbonization highlights the need to fast-track thecoordinated development and deployment of efficient cost-effective renewable technologies forthe production of CO 2 neutral energy. Currently, only 20% of global energy is provided aselectricity, while 80% is provided as fuel. Hydrogen (H 2) is the most advanced CO 2 -free fuel andprovides a ‘common’ energy currency as it can be produced via a range of renewabletechnologies, including photovoltaic (PV), wind, wave and biological systems such as microalgae,to power the next generation of H 2 fuel cells. Microalgae production systems for carbon-basedfuel (oil and ethanol) are now at the demonstration scale. This review focuses on evaluating thepotential of microalgal technologies for the commercial production of solar-driven H2 fromwater. It summarizes key global technology drivers, the potential and theoretical limits ofmicroalgal H2 production systems, emerging strategies to engineer next-generation systems andhow these fit into an evolving H 2 economy.