This is how the bioenergy facade works

What makes the bioenergy facade so productive?
Two aspects are key in allowing the facade to be highly efficient in leveraging sunlight for production of heat and biomass: The optimized blending process in the culture medium enables 8% of the incident light to be efficiently converted into biomass. For the heat, the multilayered construction of the glass elements ensures thermal insulation, leading to a heat conversion efficiency of 38%, comparable to established solar thermal devices which approach 45%.

How do you ensure the facade’s reliable and optimal functionality?
A fully automated control system (programmable logic controller) manages the facade’s entire technology with custom control software which ensures the optimal production of heat and biomass, while seeing to it that the house is supplied with hot water and heat throughout the year.

How much energy is needed to run the bioenergy facade?
The electrical energy required to run the facade is approximately 25 % as much energy as it produces in return. This is the only cost charged to you in our operator model, if cellparc is allowed to harvest and market algae biomass.

Does the bioenergy facade produce any noise?
The circulation of water and the rising gas bubbles produce a mild gurgling during the daytime. At night, the bioenergy facade is turned off and remains completely quiet.

This is how the bioenergy facade works

What happens with the algae in the bioenergy facade?
Microalgae are plants that use light, CO₂ and nutrients (N , P) for growth – creating biomass in the process. Because microalgae are unicellular, they do not grow by becoming larger but instead by dividing and thus increasing in numbers. Each cell is its own little power station – which is why microalgae grow faster than higher plants.

Where do the microalgae grow?
The algae grow in a space of about 1 cm thickness between two transparent glass panels.
This space is filled with water containing nutrients (N, P, CO₂). Periodically, gas bubbles are introduced at the bottom of the panel, turbulently mixing the water as they rise to the surface. In cycles measured in milliseconds this turbulence exchanges the algae facing the sunlight at the front of the panel with those in shade at the back, an oscillating movement that ensures that the incident light is used optimally and that all the algae are provided with enough light at all times, creating biomass in the process.

How are the panels cleaned?
The inner surfaces of the panels are constantly being cleaned by small particles whirling around in the turbulent flow of water. This allows the glass to remain perfectly clean for months on end. That is why the bioenergy facade can remain in operation continuously and without interruption.

This is how the bioenergy facade works

How is heat produced?
The heat is produced solely by the physical process of sunlight absorption into the water (culture medium). Using a heat exchanger, it is then extracted from the warm culture medium to be used for heating and warm water. The heat obtained this way has a temperature between 20 and 25 °C which can be increased to 50-70 °C as desired, using a heat pump.

This is how the bioenergy facade works

How are the algae supplied with nutrients?
All elements of the bioenergy facade are connected through a tubing system which allows for continuous recirculation of the culture medium. Nutrients (N, P and CO₂) are then added at a central point of this system whenever the concentration of nitrate is measured as falling below a certain threshold.

How much CO₂ is bound by the microalgae?
Per gram of dry biomass, approximately 2g of CO₂ is consumed, using a saturation device under 2 Bar pressure. The CO₂ is added in a dissolved condition, to fully saturate the medium. This is to avoid that the CO₂ is emitted from the culture medium before it is consumed by the microalgae.

This is how the bioenergy facade works

How are the algae harvested?
Using the method of ultrafiltration, algae are harvested automatically, whenever the cell density meets a set threshold (approx. 4 times daily). The harvesting process takes place in a filter system which allows to separate particles of a size of 32 nm and to accumulate these in the retentate up to a density of 100 g d.w./L with little input of electricity of only 2.5 W/l. Thus, the filtrate is free of any particles and can be reused for cultivation.

What happens with the algae after harvesting?
Microalgae can be marketed in various forms, including fresh, dried or as an extract of biomass. Its richness in bioactive substances, such as antioxidants, vitamins or anti-inflammatory compounds makes them attractive for use in cosmetics, animal feed or various health foods.