Four plastic jars. A hand is picking up one of them.

Swedish Algae Factory: solar efficiency from the deep

Apr 20, 2018 - 5min read

It might seem strange to suggest that the key to making solar panels more efficient might lie at the bottom of the ocean, where there’s almost no light whatsoever - but this is precisely what Swedish Algae Factory believes, and precisely why they’re cultivating organisms found in the deepest, darkest recesses of the seabed.

Sofie Allert knew from the age of 16 that she wanted to help create a society that turns technology to the advantage of the environment. Later, her bachelor thesis focused on the possibility of using algae as a biofuel, but her ideas about the energy potential of algae shifted after she met Angela Wulff, a professor of marine biology at Gothenburg University.

The two scientists looking into water with an overlay of diatoms enlarged under the microscope

“Angela specialized in algae species that grow in cold, dark environments but still survive on sunlight - under the Arctic ice, for example,” says Sofie.

“Examining these microscopic algae (or diatoms) more closely, we realised that they survived in these conditions because of the unique design of their nanoporous silica shells. They’ve evolved to trap light as efficiently as possible, enabling them to photosynthesise at depths where there is extremely little light.”

“That made us think, could we incorporate this material into solar panels to improve their performance?”

And so the Swedish Algae Factory was born, with Sofie Allert as CEO, and Professor Angela Wulff as head of research and development. But how exactly do biology and technology combine to create a more efficient solar panel?

“The algae shell material is made up of nanoporous layers,” says Sofie. “The outer layers contain larger nanopores, the inner layers contain smaller nanopores, and the pores between those layers are intertwined to create a funnel structure that can trap more light from a variety of angles.”

Algae diatoms under the microscope

“Another advantage,” says Sofie, “is that the pores’ dimensions let through visible light while blocking out UV light. This further benefits the long-term efficiency of solar panels because UV light damage is one of the factors responsible for solar panel efficiency gradually decreasing over time.”  

Swedish Algae Factory is currently focused on two primary ways of augmenting traditional silicon solar panels with this light-harvesting algae shell material; the first by building it into coatings that solar panels already use (e.g. encapsulants and anti-reflective coatings), the second by developing a new coating that can be added to existing solar panels that are already installed. The aim is to find the most straightforward way of adding these layers, to increase solar panel efficiency without dramatically increasing their cost.

For traditional silicon solar cells, an algae coating can improve efficiency by a not insignificant 4%, limited by the fact that the nanopore funnels need to be aligned with the solar panel plate. When used in a dye-sensitised solar cell (DSSC), however, efficiency can be increased by up to 60% - because the algae shell material can be blended in with the electricity-generating titanium dioxide layer, rather than added as a coating. This means the funnels don’t need to be aligned with the layer below, so can trap light hitting the solar panel from any direction.

Solar panel augmentation is just one aspect of Swedish Algae Factory’s sustainable ecosystem, however. The process of algae cultivation and its byproducts have a multitude of sustainable commercial applications, with the potential for positive impact on both an environmental and individual level.

“We grow our algae in shallow plastic trays, on sheets of biofilm,” says Sofie, “and by scraping the biofilm every 1-2 weeks, we achieve an optimal rate of algae growth that produces oxygen while consuming nitrogen and phosphorus - which are the leading causes of nutrient pollution in the world’s bodies of water.”

When an excess of nitrogen and phosphorus occurs naturally, it acts as a fertiliser which leads to accelerated algae growth - known as blooms - the decomposition of which causes large-scale environmental damage by consuming the oxygen that fish and other aquatic wildlife need to survive. The Swedish Algae factory believes that this imbalance could be redressed by using “controlled algae blooms” to clean water before returning it to the sea.

“We’re currently using controlled algae blooms to clean water for an on-land fish farm,” says Sofie, “where our algae cultivation is the first step in cleaning nitrogen and phosphorus from wastewater that will ultimately be returned to the farm. And, in the future, small systems like ours could even be used to produce clean drinking water from certain types of dirty water.”

The Swedish Algae Farm’s cultivation of algae also results in an organic biomass byproduct that contains absorbed nutrients, carbohydrates, proteins and oils, and so could be extremely useful as a source of ingredients for fish feed, fertiliser, energy and - in a version of the future that requires extremely hardcore sustainability - food for humans.

Illustration of how algae can be used in industry

But perhaps the most versatile component of the algae’s silica shells would be the UV light-blocking element - the ‘diatom frustules’. “Synthetic nanoporous materials that are currently used in products like sunscreen, paints, coatings and plastic (for example in sunglasses) are harmful to the environment and expensive to produce,” says Sofie. “Diatom frustules could perform the same function far more sustainably and Swedish Algae Factory is one of the first companies in the world to scale up the production of this material.”

There is a beautiful symmetry in this kind of biotech and biomimicry, in the simplicity of looking at how nature solves problems similar to those that we have created through human intervention.

“Over several million years of evolution,” says Sofie, “nature has found its own smart, energy-efficient solutions to ensure that life can thrive on our planet - even under extreme conditions. These solutions will often be more efficient than anything we could ever hope to synthesise. We hope our circular business model focussed around this plant-based resource can provide an example of how sustainable production can save our planet from further destruction.”

These sentiments speak powerfully to the advantages and philosophy of renewable energy, and to the essence of this precise moment in our energy history - it’s time to find an efficient way of using our planet’s natural resources; one that is as beneficial for the environment as it is for us.

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