greenhouse converter


greenhouse converter, installation view

The greenhouse converter is an apparatus for algae, water fleas and people.
Water from a fountain, enriched with atmospheric gases, especially carbon dioxide, is pumped from beneath via an air supply into an aquarium.
This feeds an algal culture which, influenced by light, produces biomass and oxygen from the carbon dioxide.
The light is observed in the aquarium as the word “beloved”, in blue, made up from single LEDs which can be individually controlled.
“Beloved” is a reference to the endosymbiosis theories of Lynn Margulis. According to her, cells with a nucleus originate from symbiotic relationships between different types of bacteria.

User interface

Then water from the fountain is also added, so that, with increased carbon dioxide content, plant growth is stimulated.
Over time, the algae grow and grow. They also colonise the word, formed of LEDs, in the water, reducing its legibility.
If algal growth is excessive then although a lot of carbon dioxide is broken down, the ecological balance threatens to tip over if the water fleas do not dispose of the algae by vigorously consuming them. To compensate, the light supply is then reduced, since water fleas avoid the yellow daylight and recognize, in the blue light, deep water which protects them from their enemies.

daphnia attracted by different light colours
internal states of the LED’s, working as sensors and effectors

The status of the display of the word “beloved” serves then as the thermometer of this little ecosystem or rather of its relationship with the greater biosphere which exists outside it.
If the word can be clearly read, with a lot of points of light displaying as blue, then the system is in a state of balance. Distortions in the ecological system will be manifested in the word becoming increasingly hard to read.

experiments with different algae
pump mechanism
Interface to regulate Oxygen input

To operate the greenhouse converter there is, alongside the aquarium, a box for a pump, with which passers-by can control the exchange of water and gas using a lever. An LCD display shows the oxygen content of the water outside and inside the aquarium. The lever creates the illusion of being in control and is a concession to the desire to be able to use technology to control nature, which derives from a state of balance.

aquarium with sufficient algal growth
Diagrammatic drawing of input and output of the system

Documentation (long version)