Algae as a source of green energy

Background: Ancient organisms

Algae are phototrophic ancient plants. More than 2 billion years ago, cyanobacteria changed the original composition of the atmosphere for the first time by adding molecular oxygen. Due to the introduction of oxygen our human existence on earth is possible. While most older generations know the rainforest as the “lungs of the earth”, it is now known that most of the oxygen comes from the marine forests. The approximately 400,000 different types of algae produce every second oxygen molecule in the air and therefore considered primary oxygen producer. A beneficial and significant side effect is the binding of the greenhouse gas carbon dioxide (CO2), which is seen as one of the driving factors of climate change.

Thus, algae provide important ecosystem services for humans. Moreover, they are used in various sectors of the industry and product development. The green all-rounders are used in food industry all the way to the pharmaceutical industry, as an alternative to plastic packaging and in wastewater treatment. Now there is another highly interesting area for algae use: bioenergy.

Innovation: Algae as green energy

In Leipzig the plant scientist Prof. Christian Wilhelm has succeeded in a new method, where he’s applying algae in a thin layer on a biofilm reactor (similar to a photovoltaic panel). The algae can be optimized in such a way that they cannot grow anymore. By fine-tuning the ratios between light, oxygen and, especially, the amount of CO2 available, the growth halt can be achieved. After absorbing CO2 and sunlight, the algae emit a useful substance: glycolate. A momentum is given here, in which the algae no longer grows but is highly productive at the same time.

Glycolate is similar to starch and can be turned into pure methane in a fermentation process, after which it is converted into energy in a biogas plant. Most of the system can be completed locally. The algae plant will preferably be in some kind of greenhouse, which is next to a silo for fermentation of the glycolate. The algae can even be watered in a closed cycle with minimal water loss.

There is another way of generating energy from algae. The metabolism of algae is related to two interesting energy sources. The first, we discussed above, the second is hydrogen, which is already used in Nordic countries as car fuel. Hydrogen can be produced using principles of sulfur reduction and the help of the enzyme hydrogenase. The result is an energy carrier that is easy to store and can be placed in a fuel cell at any time. Hereby, a living powerplant is created that can produce CO2-neutral energy.

Potential: Tiny power plants

In contrast to most fuels and energy suppliers, the energy gain from algae is almost climate-neutral and goes along with the idea of a circular economy. Moreover, other bioenergy sources, such as corn and rapeseed are in competition with food for land and therefore have already been under increasing criticism. Algae, on the other hand, can be grown in very small space without contributing to soil erosion and contamination. The mini power plants can be installed on roofs, in greenhouses and even in lighted basements. This is a significant advantage over other energy plants. We see great potential for more sustainable and clean energy in this new green energy supply.

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