A team of the University of Pretoria (UP) is leading a study of natural hydrogen gas discovered under the Earth’s surface in Mpumalanga. Natural hydrogen is a source of renewable energy that could substantially help address the country’s current energy challenge.
Hydrogen South Africa HySA
As part of decarbonising and reducing in its reliance on fossil fuel, South Africa is exploring hydrogen as an alternative source of clean energy. The department of science and innovation (DSI)’s predecessor, department of science and technology, initiated the establishment of Hydrogen South Africa (HySA) which cabinet subsequently approved in 2007. Among others, the HySA aims to harness South Africa’s mineral endowments to promote the hydrogen economy and renewable energy use, and to incorporate PGM-based components in hydrogen fuel cell and related technologies because they are cost-effective and sustainable.
HyAfrica project
The discovery of the natural hydrogen gas was made as part of the HyAfrica project undertaken by a consortium of partners within the European Union (EU) and African Union (AU). The project was tasked with looking for sources of natural hydrogen in Africa, and exploring the possibility of using natural hydrogen for stand-alone renewable energy solutions. The partners fall under the umbrella of LEAP-RE (Long-term Joint EU-AU Research and Innovation Partnership on Renewable Energy). The AU partners are in Morocco, Togo, South Africa and Mozambique.
Collecting field data
Even though it is too early to ascertain how much of an effect the discovery of the natural hydrogen gas would have on the country’s national grid if fully exploited, for now the scientists are looking at small “stand-alone” generation units for local domestic or minor industrial use. Said Professor Adam Bumby, a structural geologist at UP and one of the scientists involved in the study: “We began collecting field data in Mpumalanga in June 2023.”
He added that: “A notable highlight was finding an area near Hendrina where we recorded natural hydrogen in the soil beyond the detection limits of our hydrogen meter (10 000 ppm). The ‘normal’ background reading of hydrogen in soils and the atmosphere is 0.5 ppm. Clearly, this implies a significant increase in hydrogen from the rocks below that area.” He said this “untapped renewable, non-polluting energy supply that has gone unnoticed for centuries, right under our noses!”.
More potential source sites
Professor Bumby further said that: “Only in the past few years have geoscientists started to measure natural hydrogen flux out of the Earth, and we have already demonstrated that this is the case in parts of Mpumalanga. Our local scientists, with their geological and geophysical knowledge of the potential source rocks, combined with the expertise of our European partners, are proving to be a successful team.”
Professor Bumby said they are in the process of identifying potential source sites, after which they will be able to quantify estimated resources, adding that the project represents a milestone in the research agenda of those involved. Recent samples taken in Mpumalanga currently fall under the natural or “white” hydrogen category. According to Professor Bumby, follow-up field trips and isotopic comparisons of all the hydrogen samples collected will provide a clearer understanding of the geological controls responsible for generating hydrogen in Mpumalanga. He said it is difficult to estimate at this point how long it will take to properly exploit any decent reserves of hydrogen, adding that hydrogen is considered a fuel of the future due to it emitting zero emissions.
Various uses of hydrogen gas
Professor Bumby explained some of the benefits of hydrogen. He said it can be used, for instance, in car engines instead of petrol, producing water as the exhaust gas. It is the most common element in the solar system but sadly, he said, most of it is either sitting or burning in the sun. Hydrogen can also be synthesised from water using electrolysis, but it requires a lot of energy to split water. The energy to produce hydrogen fuel by electrolysis of water can be sourced from renewables (such as solar energy or wind turbines) and is called “green” hydrogen”. Alternatively, the energy needed for the split can be sourced by burning fossil fuels (“grey” hydrogen”), but that produces carbon dioxide, which is a greenhouse gas. If that greenhouse gas is captured and stored (sequestered), it’s called “blue” hydrogen.
Decay of radioactive elements
Natural hydrogen (or “white” hydrogen) is different because the energy needed to break the hydrogen from water is provided by geological processes through chemical reactions in rocks driven by high temperatures at depth in the Earth’s crust (serpentinisation). The decay of radioactive elements in some minerals deep within the Earth’s crust can also result in hydrogen being split off from water (radiolysis). “Because these reactions and processes are occurring relentlessly in some geological environments, the hydrogen that is produced by these natural processes can be considered renewable,” Professor Bumby explained.
Climate change activists
Continued Professor Bumby: “Because hydrogen is a very light element, it readily rises towards the Earth’s surface, where it either gets trapped under impermeable rock layers or leaks up to the surface. It is these leaks of natural hydrogen that we are trying to trace in Mpumalanga for this part of the HyAfrica project.” He added that environmentalists and climate change activists will also be interested in the potential impact of the development of natural hydrogen as a commodity in South Africa.
Contributing to global warming
“In other areas where hydrogen has been exploited in the past, the extraction of natural hydrogen typically requires drilling a borehole, and a motor engine adapted to run on hydrogen,” he said. “No further invasive procedures are envisioned. Burning hydrogen in engines does not produce any carbon dioxide – or any other greenhouse gas – that contributes to global warming. The only combustion product is water. If the hydrogen is not exploited, it seeps from the Earth into the atmosphere, reacts with oxygen and still forms water,” added Professor Bumby. He said there still remains a great deal of work ahead for the team to consider necessary regulation and legislation associated with exploitation of these resources.
