Bacteria convert water hyacinth into green hydrogen

Scientists from the private Technical University of Loja in Ecuador study how bacteria convert water hyacinth into green hydrogen.

In Ecuador they are investigating the possibility of using microorganisms to produce clean and renewable fuels. From water hyacinth, bacteria produce them through dark fermentation.

It was in the 17th century when a man named Antonie van Leeuwenhoek challenged the beliefs of his time. By observing a simple drop of water through a homemade microscope, he discovered a hitherto invisible universe: the world of microorganisms. This event, considered the beginning of the microbial revolution, radically changed our understanding of life and the fundamental processes that occur on Earth.

Before the advent of microbiology and the subsequent development of biochemistry, our understanding of some natural phenomena was very limited. For example, we did not know the causes of food spoilage, the diseases that afflict us, and the fermentation processes that create staple foods such as bread, cheese, and Andean chicha. The belief in the spontaneous generation of life from inert matter was an indisputable dogma.

The gender Clostridium, which includes anaerobic bacteria commonly found in a variety of environments such as soil, sediments and the gastrointestinal tract of animals and humans, has become the subject of increasing interest in the area of ​​biotechnology, especially for the production of biofuels like hydrogen.

Species of the Clostridium genus can produce hydrogen from simple sugars, which in turn can be obtained from various sources, for example agricultural and forestry waste, which are characterized by a high lignocellulose content.

Microorganisms and energy production

In the field of biotechnology, these tiny organisms play an important role in the production of medicines, biofuels and fermentation products, as well as in biological processing processes. According to Paulina Aguirre, professor of environmental engineering at the Private Technical University of Loja (UTPL): “Thanks to the metabolic capacity of microorganisms, it is possible to explore a wide range of applications, ranging from energy generation to waste reduction effectively.".

In 2023, green, low-emission hydrogen represented only 0,7% of global hydrogen consumption, estimated at 95 million tons. “Although green hydrogen is clean during use, its production can be polluting if it is based on traditional energy sources such as coal or gas.”explains Aguirre.

In this context, microbial hydrogen production seems to be a promising direction. This line of research focuses on developing biological methods for the production of green hydrogen, positioning it as a renewable and sustainable energy source.

Biochemical process of obtaining green hydrogen

green hydrogen

Hydrogen is an important reagent in various biochemical processes carried out by many microorganisms.
Some consume it to speed up metabolism in a process similar to respiration, while others produce it through fermentation. Additionally, some bacteria use it to convert atmospheric nitrogen into ammonia, enriching the soil with the nutrients plants need.

Using a biotechnological process called dark fermentation, Aguirre's team uses water hyacinth as a raw material. “This plant is widely used in treatment processes due to its ability to capture heavy metals, but now it has become a pest. This, combined with its high cellulose content, makes it a good candidate for clean hydrogen production.”, explains the researcher.

Once collected, the raw material undergoes pretreatment, in which its plant structure decomposes, releasing sugars such as glucose. It is food for bacteria of the genus Clostridium, which initiate dark fermentation in an anaerobic environment. Like mini biological factories, these bacteria process glucose and produce hydrogen as a byproduct of their metabolism, which accumulates at the top of the bioreactor where it can be recovered.

66% testing efficiency

The tests carried out in the laboratory achieved a hydrogen production efficiency of up to 66% with respect to the glucose used as raw material, resulting in a cost of approximately $2,50 per kg of green hydrogen, with ample room to reduce this value by improving the process and reducing operating costs.

In addition to hydrogen, lactic, butyric and acetic acids are also obtained from this process, which have many applications. Lactic acid plays a role in the food industry, but it also stimulates the production of biodegradable plastics. Butyric acid, known for its use in perfumery, also plays an important role in the production of biofuels. In turn, acetic acid, necessary for the production of vinegar, is used for medical purposes as an antiseptic, as well as in the industrial production of various chemical compounds.

Aguirre said the process has been tested in the laboratory and that she and her team are working to improve several key aspects to improve its effectiveness. We hope to soon begin the process of scaling up to a suitable environment that simulates real-world operating conditions. This move will be an important step towards the industrialization of this technology in the near future.

A characteristic element of the researcher's work strategy is the use of water hyacinth as raw material.
This plant can be used as a bioremediator in freshwater reservoirs and the excess plant matter produced in the process can be used to produce green hydrogen.

This will not only allow the recycling of liquid waste but also the full use of the biomass produced, in line with the concept of circular economy.

According to the researcher: "Our approach has a double environmental benefit both for the bioremediation of lake bodies and for the production of biohydrogen. If we also consider the industrial use of acids, we are talking about a biorefinery where we seek the generation of zero waste."

One of the main challenges associated with the efficient use of hydrogen on a large scale is its storage. “Hydrogen is one of the purest elements in nature but also the most explosive. Thanks to this it has a great energy capacity", - stated the researcher.

Hydrogen's high energy potential makes it an ideal candidate for a future clean fuel, but its reactivity and high volatility pose special challenges for its safe storage and transportation. Compression, liquefaction or freezing are some of the solutions that have been proposed and it is expected that this technology will continue to develop.

Safe and convenient storage for green hydrogen

These solutions aim to not only make hydrogen storage safer and more practical, but also more energy efficient. Overcoming these obstacles is essential to integrating hydrogen into our energy infrastructure and realizing its potential as a clean, renewable energy source.

Hydrogen plays an important role in the transition to a low-carbon economy, mainly because it is a clean and flexible energy source.

When hydrogen is burned, only water vapor is produced as a byproduct, making it an attractive tool for reducing greenhouse gas emissions.

Financial services rating agency S&P Global estimates that by 2050, global demand for green hydrogen will reach 614 million tons per year, representing around 12% of total energy consumption.

Pauline Aguirre remembers that “Initially solar panels were a fairly expensive technology, but now they can be installed even in your home. Developing green hydrogen for everyday use will also take time, but it will happen".

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