In a prototype of an urban algae farm now on display in an exhibition in Kazakhstan, shows how algae could fit inside existing buildings where people live and work. Designers suspended coils of lightweight glass tubes from the ceiling, attached to pumps that visitors can press to send carbon dioxide into the algae and help it grow. The designers estimate that their aesthetically-pleasing prototype can efficiently produce an average of 672 grams of protein each day, the equivalent of what eight cows can produce in 660 days. The harvested algae could be used to produce energy for heating or electricity, or be sent off to be used in algae-based products.