Introduction

Solar assisted steam/methane reforming

Low temperature alkaline electrolysis powered by solar photovoltaic and wind

Concentrated solar electricity and low temperature electrolysis

High temperature steam electrolysis

Thermochemical water splitting

Summary of results

Sensitivity analysis

Conclusion

References

Abstract

Global warming and tightening environmental legislation is putting pressure on divesting from fossil fuel in the energy sector, with the transport sector likely to see the biggest changes. Current alternative energy sources are electric vehicles and hydrogen. Conventional hydrogen production technologies are fossil fuel based, emitting significant amounts of CO2 into the atmosphere. This paper explores various ways to integrate solar thermal technologies into hydrogen production to generate carbon free hydrogen in South Africa. South Africa’s abundant solar resource indicates that the country may become a significant player in the hydrogen market. However, the high capital cost associated with solar thermal energy put solar thermal hydrogen at a price disadvantage against conventional production technologies. Significant market penetration for solar thermal hydrogen is not expected within the next decade, but cost reduction due to improved manufacturing techniques and larger manufacturing volumes might close the gap in the long term.

Introduction

Fossil fuels have become indispensable in the transport sector over the last century. Its continued use is under thread, due to the rapid depletion of the resource. Furthermore, burning fossil fuels release vast quantities of CO2 into the atmosphere that contributes towards global warming. NOx and hydrocarbons, also emitted by burning fossil fuels, cause smog and corresponding health issues in cities. The United Nation Climate Change Secretariat coordinates international efforts to mitigating the effect of climate change. A total of 192 countries have ratified its Kyoto protocol and 179 its Paris agreement [1]. These countries are committed to reduce their CO2 emissions, and tabled plans to reduce their carbon footprint. High cost and increasingly more stringent environmental regulations are expected to be strong drivers for divestment in fossil fuels in future. Two technologies are currently competing as alternatives to the internal combustion engine in the mobility sector, namely electric cars and hydrogen fuel cells. Electric vehicles hold a slight advantage in that it can benefit from an existing electricity distribution network. Their batteries can act as a distributed energy storage system that may help to mitigate the inherent intermittent nature of renewable energy source. A limited range of ±۱۰۰ km and long recharging times (±۸ h) are seen as the main obstacles for large scale deployment. Ground-breaking work by Tesla managed to increase the range to over 400 km. Hydrogen fuel cells’ main advantage over electric cars is their extended range (over 800 km) and rapid refuelling. High cost and lack of infrastructure are the most important barriers in the way of large scale deployment; both are expected to respond favourably to large production volumes. Of course, CO2 mitigation targets can only be reached if electricity or hydrogen is produced from renewable energy sources.