Chemicals and materials made from algae have many functional and environmental advantages over those made from petroleum. However, facilities capable of turning them into useful products are still rare across the world, including in Europe. Why have algal biorefineries not scaled and how could it be done?
A promising sustainable feedstock
Algae is an emerging source of raw materials for biorefineries, factories that process biological matter into economically valuable chemicals and materials.
These aquatic plants are seen as ideal raw materials for sustainable manufacturing. Algae holds an immense number of complex chemicals that hold applications across several industries: proteins, lipids, carbohydrates, pigments and other bioactive components. They also grow rapidly and are effective at absorbing carbon.
Yet for all its advantages, biorefineries for making algal products are still rare. The Integrated Biorefineries Mission (IBM), a global initiative of 23 countries and the European Commission, has collected data confirming that it remains one of the least common feedstocks used in biorefineries.
Algae and marine feedstock facilities numbered less than 100 across IBM member countries, amounting to under 4%. Only waste oils and animal waste were less common.
Agricultural residues were the most common biorefinery feedstock at around 900 projects between the member states.
Cost remains an issue
Companies often cite high investment costs and costs for feedstock as issues holding back the scaling of algae-based products. The reality is that algae biomass costs remain too high to be competitive for biorefinery producers compared to woody biomass or custom-grown land-based crops.
At heart this is a supply issue – there is still not enough algal biomass available to ground a high-volume industry. Algae can be harvested wild but we really need a major cultivation industry before any biorefinery industry can get going. Growing them in either photobioreactors or open ponds is the only way to obtain large enough volumes at a consistent quality and low cost.
Europe is a long way off from hosting a major algae cultivation industry since the continent’s production accounts for only 1.14% of global biomass between 2006 and 2015, with Norway dominating at 65%.
Circular microalgae for cheaper cultivation
However, there are solutions to the feedstock cost problem, meaning there is more the industry can do than simply wait for subsidies or for renewable material demand to skyrocket.
Cultivated microalgae holds better scaling potential than macroalgae, which are the larger frond-like algae commonly seen washed up on beaches. One of microalgae’s advantages is that it can often feed on waste nutrient sources, saving on environmental impacts and allowing for cultivation on the cheap.
One route the industry can take to scaling is to integrate microalgae cultivation into existing industrial sites. The most tempting possibility is to grow microalgae at a large scale as a water purifying biotech for waste water treatment sites. If the microalgae can serve multiple industrial functions over its life cycle, it can become economic more quickly: once it has served its purpose as a water purifier, the algal mass can be harvested and dried into bio-based fertiliser, or other products.
Another possibility is to integrate microalgae farms into biogas and pyrolysis plants. Here, an anaerobic digester breaks down algae harvested from ponds to produce waste gas methane and a nutrient-rich solid matter. The waste methane could then be used in gasification, a process that can convert waste wood into biochar and other useful products. Waste gases from this second process are then pumped into algal ponds to accelerate their growth.
Lowering costs in the biorefinery
Feedstock costs are one thing but the high costs of actually processing the algae also explains why algal biorefineries and products are still rare.
Analysts and industry players agree that making multiple different products in the biorefinery at the same time from the same biomass is needed to achieve economic production.
This could mean that a single batch of algal feedstock would be processed into biodiesel, biobutanol, acetone, ethanol, and glycerol. This multi-functional algae biorefinery would not rely on a single end product to be viable.
Cost reduction can also be achieved by fine tuning the technologies used for harvesting desired chemicals from the algae. The ideal here would be a chemical that could extract the bioactive compounds of interest from microalgae without disrupting their cell.
Extraction of the chemicals from the mature algae is one of the most expensive and technically difficult parts of the process. One estimate places harvesting costs at about 40% of total expenses in biorefinery operation.
Each target chemical has to be drawn out of the microalgae without any loss or degradation in the quality of other compounds. This demands a high degree of precision on a tiny scale – not characteristics easily achievable in large-scale industrial production.
Currently, extraction commonly draws on the use of enzymes and solvents but these are expensive. One promising technology however is extraction via supercritical carbon dioxide , a method without any hazardous solvent materials and one that is highly selective, using the recyclable material of carbon dioxide.
This is the most economically viable extraction method because of the abundance of carbon feedstock. Unlike some other physical extraction methods for microalgae, it does not require much heat and energy. The capital costs may be high but could rapidly pay for itself if operations scale.
Operating algae biorefineries in Europe
In Europe, algal processing capacity is still rare but not non-existent, showing that producing with algae can be done.
In Austria there is Ecoduna AG that produces microalgae for food, food supplements, cosmetics and more. The biorefinery grows their microalgae in vertical rows of 6 metre high glass tubes designed to maximise the amount of light the algae can access. To achieve maximum yield, the company, like all other algae producers, are highly attentive to all the growth parameters like pH and carbon dioxide content of the growing medium inside the glass.
There is also Italy’s Biorefinery di Gela which has been operating a multi-feedstock operation since 2019. The plant does not specialise in algae but does have the capability to process it, alongside a wide range of other feedstocks like cooking and frying oils, animal fats and waste from plant-oil processing, and lignocellulosic materials.
One of the most recent facilities to open that is dedicated to high-value algal applications is near Montpellier in the south of France owned by the company Microphyt. The site is partly funded by the EU’s Bio-based Industries Joint Undertaking facility in 2021.
Like Austria’s Ecoduna, Microphyt’s French facility grows algae inside futuristic-looking clear tubes that line its indoor cultivation spaces. The target industries are nutrition and beauty, producing things like weight management supplements, cognitive health supplements, and skin-enhancing compounds.
The company says the plant “represents the first-of-its-kind fully-integrated microalgae biorefinery at an industrial scale”. Certainly the plant takes a novel approach to raising algal productivity, the obsession of any company in this space. It applies biomimicry, the use of biological and ecological mechanisms observed in nature to human technologies, to increase algae harvests.
The technology mimics growth conditions in nature that encourage high algal growth rates. This indoor rendering of an ideal natural environment for algae means that species not usually suited to industrial applications can now be exploited.
In Finland, Origin by Ocean and AFRY have entered a collaborative engineering collaboration to plan an industrial-scale biorefinery for processing bio-based seaweed products. The feedstock for this biorefinery is slightly different to the advanced microalgae plants that dot across Europe. Instead of growing microalgae, they are planning to use up wild-harvested invasive macroalgae, seaweed that wash up in their thousands of tonnes on the beaches of Europe, the Caribbean and Norway.
Then there is Tomalgae in Nevele, Belgium is the world’s first algae production facility dedicated solely to aquaculture feed. The project will target waste water treatment companies Algae biomass and thus waste water can be turned into high added value and biobased products.
Cost may have held back the growth of further algae biorefineries in Europe but there are now viable production techniques for reducing these. Some even encourage circularity in other industries, such as the integration of microalgae cultivation into wastewater treatments.
Although room exists for farms that cultivate bigger seaweed species at scale for industry, microalgae seems to be the most viable route for scaling algal biorefineries. Getting harvesting methods right here is key, as extracting chemicals from the tiny bodies of these organisms can racks up costs.
