Controlled CO₂ supply for algae growth

Radius, a strategic research group of the Belgian Thomas More University of Applied Sciences, investigates the conversion of CO₂ with sunlight into specialty chemicals. Microalgae play a key role here, and their CO₂ fixation rates and growth capacities are examined. 

This research falls within European efforts to build a low-carbon economy to guarantee a sustainable, reliable and affordable supply of energy (e.g. biofuel) and materials (e.g. chemicals and cosmetics). In this respect, the greenhouse gas carbon dioxide (CO₂ ) is considered a valuable alternative source of carbon that is abundantly available, in applications for food, feed and biobased chemicals.

The researchers of Radius cultivate microalgae in photobioreactors. In order to investigate how much CO₂ gas is captured and converted by their algae, they need an accurate method to control and measure the CO₂ gas flow supplied to the algae during cultivation. To this end, the help of Bronkhorst's devices was requested.

Process solution

At Radius, experiments for microalgae cultivation on a pilot scale are conducted in closed, tubular photobioreactors with a total volume of 300 liters each, operating at atmospheric pressure in a climate-controlled greenhouse. Two IN-FLOW thermal mass flow controllers are used, each of them to supply CO₂ to these pilot scale reactors, with a maximum dosed flow rate of 886 milliliters CO₂ per minute for each reactor. There is a direct, automatic feedback between the current measured pH value and the supplied CO₂ flow to optimize growth conditoins in this algae bioreactor application.

After a meeting with their supplier of CO₂ gas, Radius was introduced to Gefran, which is a distributor of Bronkhorst products in Belgium. Radius and Gefran together looked for a system that could accurately dose CO₂ based on the pH value in the growth medium of the microalgae. The combination of their requirements ultimately led to the purchase of  the IN-FLOW mass flow controllers from Bronkhorst.