Biofuel from algae

Heavy metals from industrial pollution are found even in algae. Bad news ? Not for researchers trying to extract these rare metals in order to produce biofuel.

“We’ve been working on producing biofuels from algae since 2015,” says Scott Edmundson, a botanist who heads the biogeochemistry section at the US government’s Pacific Northwest National Laboratory (PNNL). “Quite quickly, we encountered the problem of algae residue. How can you get rid of them other than sending them to the landfill? Just before the pandemic, I had the idea of ​​purifying the metals present in algae. Several are rare metals essential to the energy transition. »

Last December, Mr. Edmundson demonstrated in a report that it is economically profitable to extract “lanthanides”, a family of 15 chemical elements which are part of the “rare earths”, used in batteries from certain algae. His project, called “Uncle Sam” (Extraction of Critical Lanthanides Not Achieved by Algal Biominerals), has just been chosen by a biomineral technology grant program from the US Department of Energy.

“Ultimately, we could simply sell proteins extracted from algae,” continues Mr. Edmundson, “a market which currently exists, but which is limited to algae not contaminated by pollution. »

The only other group in the world studying this issue is located in Portugal. “He has been working for about ten years on the use of algae as pollution sentinels,” says Mr. Edmundson. It is the work of these researchers which has shown the potential of algae to bioaccumulate certain pollutants, including certain rare metals. Like me, they realized that we could extract these minerals, which are currently either extracted in poor countries, at war, or controlled by China. »

Harm ecosystems?

At Laval University, biologist Ladd Erik Johnson, an algae specialist, believes that targeting rare minerals in algae could be a viable strategy. “There are plenty of examples of people who have proposed using algae to extract different molecules,” says Mr. Johnson. But generally, we come up against limits, we cannot produce enough. We produce proteins for cosmetic products, for example. Or we take algae as such as fertilizer or components of food products. »

The danger, according to Mr Johnson, is that algae mining threatens ecosystems.

What is the concentration of certain metals and minerals in algae used for? “Japanese researchers showed, in 2011, that lanthanides made certain enzymes in algae more active. Since then, it has been a booming area of ​​research. »

Making desalination plants profitable

Traditionally, biomineral projects used bacteria to produce these minerals. “But we have quantity limitations and significant costs,” says Mr. Edmundson. This is because bacteria are inserted into seawater basins to biologically concentrate minerals and metals. But the process is slow, so the quantities produced are limited.

One of the notable episodes in the history of biominerals involves the inventor of chemical fertilizers, the German Fritz Haber. “After World War I, he calculated that Germany could repay its war debts by extracting gold from seawater,” Mr. Edmundson said. As he was the most renowned chemist in the world, the German government listened to him. He installed extractors on ships carrying passengers in the Atlantic. But he had based his calculations on a sample placed in a dirty beaker. So he collected 1000 times less gold than expected. »

Could the bioaccumulation of metals in algae make Fritz Haber’s dream profitable? “Maybe not directly, but by extracting other rare minerals, we could perhaps make the extraction of gold from algae profitable. »

Algae in Quebec…

A handful of Quebec companies exploit edible algae, according to Ladd Erik Johnson. “It’s especially in Chaleur Bay, they are very small businesses. » According to a 2021 article from the Order of Dietitians of Quebec, 14 species of algae are harvested artisanally in Quebec and one is cultivated.

…and in China

China is the world’s giant in algae harvesting. Two thirds of world production, more than 2.5 million tonnes per year, takes place in the Middle Kingdom, according to a Chinese study published in 2015 in the Journal of Applied Phycology. More than 90% of Chinese production is food. “Seaweed is very popular in Asian cuisine and China has done a lot of research into its use in other areas, including as fertilizer,” says Mr Johnson.