For years, green hydrogen has emerged as a leading contender for driving the global energy transition. Its ability to generate clean energy without emitting pollutants has ignited worldwide interest in decarbonizing production and energy sectors. In this context, Chile has become an international leader in developing this technology, leveraging its abundant solar and wind resources and a strong national commitment to clean energy production.
Chile’s hydrogen production efforts have largely centered on water electrolysis, which utilizes electricity to split water into its elemental components. However, this focus has often overlooked promising and complementary avenues such as biohydrogen generation: a renewable approach that transforms organic waste through biological processes. This method holds significant relevance for Chile, a nation that produces vast amounts of waste from industries like pork and algae. Properly harnessed, this waste could be converted into a vital source of clean energy, mitigating its environmental impact.
An innovative approach to generating green hydrogen from organic waste, specifically pig manure and the macroalgae Durvillaea Antarctica (commonly known in Spanish as cochayuyo), is being explored through a Fondecyt Regular project at the University of Santiago, Chile. The project is spearheaded by Dr. Jhosané Pagés from the Department of Chemical Engineering and Bioprocesses.
“Due to its high organic matter and nitrogen content, pig slurry is a complex substrate that is difficult to use efficiently in biological processes,” states the researcher. “Our research shows that co-digesting it with Durvillaea Antarctica, which is rich in sugars and lignin-free, enhances biological degradation and boosts biohydrogen yield.”
Durvillaea Antarctica, a carbohydrate-rich seaweed abundant on the Chilean coast, improves the carbon/nitrogen ratio of the system, promoting the production of biohydrogen, biomethane, and volatile fatty acids. This combination would not only enhance the process’s energy yield but also enable the recovery of waste currently destined for landfills.
“We aim to revalue discarded waste, transforming it into clean energy vectors instead of letting it remain a pollutant,” states Dr. Pagés. “This co-digestion method not only optimizes the biohydrogen production process but also paves the way for a truly sustainable and replicable model, especially beneficial for areas generating substantial agro-industrial waste.”
To evaluate the energy potential of the pig manure and cochayuyo mixture, the team will conduct laboratory tests using the Biohydrogen Potential Test. This test simulates anaerobic degradation of organic waste by microorganisms, generating gases like biohydrogen. By testing various mixture proportions, the team can compare their behavior and performance. This initial analysis will determine which waste combination produces the most energy and how it impacts biological process stability.
Furthermore, the initiative incorporates biochar, a porous material produced by heating plant biomass – specifically cochayuyo – in an oxygen-deprived environment. Introduced into the biological reactor, this biochar provides a surface for microorganisms to attach and function more effectively. It also acts as a filter, trapping excess nitrogen that the process doesn’t naturally remove. This exemplifies a more complete circular approach, where waste from the Quinta Normal area and potentially coastal regions isn’t just transformed into clean energy but also used to reduce pollution and create beneficial by-products with fertilizing applications.
Dr. Pagés elaborates, “Our goal is to leverage biochar—derived from the same algae waste—as an additive to enhance the process. Because these substrates produce nitrogen that isn’t biologically eliminated, we’ll assess biochar’s ability to capture it within the reactor. Crucially, we’ll also research how to improve its nitrogen adsorption capacity by modifying its surface using industrial by-products such as bischofite and steel dust.”
Structured in four stages, the project begins by testing diverse combinations of liquid manure and cochayuyo to determine their biohydrogen and biomethane yield. The second phase will involve evaluating biochar’s influence on both the primary process and nitrogen removal. Following this, continuous operational tests will be conducted to confirm the system’s sustained stability. The final stage will explore the feasibility of utilizing the employed biochar as an adsorbent for unremoved nitrogen from the biological process, alongside its potential application as a biofertilizer.
“Our success in not just treating this waste, but in converting it into clean energy and valuable societal by-products, means recovering a significant untapped potential,” concluded the researcher. “I would be immensely satisfied if we could truly add value to waste, moving beyond simple pollution reduction to fully harness its energy and environmental benefits.”