Engineering News and Mining Weekly
Unnoticed for Centuries?
University of Pretoria scientists lead study on natural hydrogen find in Mpumalanga
Scientists at the University of Pretoria (UP) are leading a study on natural hydrogen gas discovered beneath the Earth’s surface in Mpumalanga.
The gas could be a source of renewable energy that could contribute to the national energy budget and help address the energy shortage in South Africa, the researchers note.
While it is still too early to know how much of an effect the discovery could have on the country’s national energy landscape if exploited, the scientists envisage small standalone generation units, powering generators with a capacity of about 20 kW, for local domestic or minor industrial use.
“There might well be an untapped renewable, non-polluting energy supply that has gone unnoticed for centuries, right under our noses. 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,” structural geologist Professor Adam Bumby says.
He adds that they are in the process of identifying potential source sites, after which they will be able to quantify estimated resources.
“The role of this project is to indicate the presence of hydrogen and how it could be incorporated into the national energy budget if it were to be exploited,” he explains.
This discovery was made as part of the HyAfrica project undertaken by a consortium of partners within the European Union (EU) and the African Union (AU).
Recent samples taken in Mpumalanga currently fall under the natural or white hydrogen category. 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.
Bumby says it is difficult to estimate at this point how long it will take to properly exploit any decent reserves of hydrogen.
He adds that hydrogen is considered a fuel of the future owing to its potential to generate zero emissions, depending on the type of hydrogen that is produced.
“It can be used, for instance, in car engines instead of petrol, producing water as the exhaust gas. Hydrogen is the most common element in the solar system but, sadly, 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,” he explains.
The energy to produce hydrogen fuel by electrolysing water can be sourced from renewable sources, such as solar energy or wind turbines, resulting in green hydrogen. The energy needed for electrolysis can alternatively be sourced by burning fossil fuels to produce grey hydrogen, where the burning of fossil fuels produces carbon dioxide (CO2) – a greenhouse gas (GHG). If that GHG is captured and stored, it results in blue hydrogen.
Natural white hydrogen is different because the energy needed to separate the hydrogen atoms from the oxygen atoms in water is provided by natural geological processes through chemical reactions in rocks, driven by high temperatures at depth in the Earth’s crust – a process called 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 – a process called 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.
“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,” Bumby explains.
He adds that environmentalists and climate change activists might also be interested in the potential impact of the development of natural hydrogen as a commodity in South Africa.
“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. No further invasive procedures are envisioned.
“Burning hydrogen in engines does not produce any CO2 or any other GHG 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,” Bumby explains.
The HyAfrica project is tasked with looking for sources of natural hydrogen in Africa and exploring the possibility of using natural hydrogen for standalone renewable energy solutions.
The partners fall under the umbrella of Long-term Joint EU-AU Research and Innovation Partnership on Renewable Energy (LEAP-RE), with the AU partners being in Morocco, Togo, South Africa and Mozambique.
The South African scientific partners in the HyAfrica consortium include UP Department of Geology representatives Bumby and Dr Ansie Smit and UP Graduate School of Technology Management Professor David Walwyn, along with University of Limpopo researchers Samson Masango and Professor Napoleon Hammond.