Students at the University of Cambridge have been awarded first prize in the 3rd CIB International Conference on Smart and Sustainable Built Environments for their AlgaeHouse concept, a design for an energy and carbon-neutral house powered entirely by algae.
Dispel any thoughts of a slimy, moist underground cave or greenhouse: the team's designs are stylish, neat and modern. The house features a sweeping, angled window which in addition to looking rather impressive, houses a number of tubes containing algae which have been genetically engineered for maximum photosynthetic efficiency: when deprived of sulphur, algae will produce hydrogen, which can be fed into a fuel cell for conversion into electricity.
The key to optimising production of hydrogen in algae is maintaining a stable temperature, which the team's architectural design cleverly achieves using a "moat" to reflect different degrees of light towards the algae-infused window according to the time of year. During the summer months when the sun is highest, a higher proportion of sunlight passes below the water surface where infrared light (which carries the most heat energy) is absorbed, therefore filtering the amount of light that ultimately reaches the algae. In winter months, the sun's angle of incidence is lower, and thus the algae benefits from maximum exposure to the heat of direct sunlight and light reflected off the moat's surface.
However, algae are not able to produce hydrogen for sustained periods, so the team has taken advantage of other system by-products to optimise energy production. Energy-storing molecules known as Lipids, which are extracted from "dry" or unproductive algae, can be used as another source of hydrogen when fed through a catalytic reactor. Any remaining algae biomass, which would otherwise be system waste, can be fed into an anaerobic digester for conversion into biogas and used for water heating.
The system also makes use of other household waste as an input to energy generation: "brown water" from the bathroom and carbon dioxide from heating and other household systems are synthesised into nutrients for growing further algae.
The result is a closed biological system which is able to produce 4100 kWh per year, enough to power a modest two-person household with all the regular electronic appliances and whitegoods. Or put another way, enough energy to drive a BMW Mini E from London to Beijing and back - twice.
This article was originally published by WIRED UK
