On the 24 February, leaving the dark, drizzling London behind, I went to Hamburg, Germany to visit the world’s first ‘green’ house – BIQ algal house which has a microalgae bioreactor to capture CO2 and generate energy. The house, which contains 15 residential apartments, opened its doors in April 2013 at the site of the International Building Exhibition (IBA) Hamburg. Dr Martin Kerner, Managing Director of Strategic Science Consult GmbH (SSC), greeted me outside the BIQ house.
The BIQ house is the world’s first project to demonstrate a full scale bioactive facade. The facade system is the result of three years of research and development by a consortium including Colt International, ARUP GmbH and SSC GmbH based on a bioreactor patent held by SSC. In total, 129 bioreactors (200 m2) have been installed on the south west and south east faces of the four-storey building.
Two 2.8m x 0.7m vertical facade panels form a 0.18m thick cavity with a capacity of 24 litres for the circulation of liquids and growth of algae. For safety and thermal insulation, the bioreactor is clad on both sides with laminated safety glass. Compressed air is pumped in from the bottom of each bioreactor at certain time intervals. The gas emerges as large air bubbles visible to the naked eye (the white dots on the second line of the panels in the photo of the BIQ house) and generates an upstream water flow and turbulence to stimulate the intake of CO2 and light by the algae. At the same time, the inner surface of the facade panels are washed by the mixture of water and air.
A membrane technology, developed by Helmholtz-Zentrum Geesthacht in cooperation with SSC, is used to provide an enriched CO2 (up to 60%) stream from flue gas, generated on site from burning methane. The concentrated CO2 is then dissolved and circulated to the algae inside the facade, together with the nutrients and water. All the service pipes for the inflow and outflow of the culture medium and gas are integrated into the substructure of the bioreactor system as a closed loop system and connected to the control room. A central building management system controls all the processes necessary to operate the bioreactor and fully integrate it with the building’s energy management system. This includes the control of the algal cell density and the temperature in the culture medium.
Apart from housing microalgae for photosynthesis, the facade also collects the energy by absorbing the light that is not used by the algae and generating heat as a solar thermal unit. The heat obtained from the facade has a temperature of about 40oC, and is removed from the culture medium by a heat exchanger. It is then either used directly to heat the building or is stored in the ground by an underground geothermal system. The generated biomass is harvested from the culture medium by flotation. Although algal biomass can be burnt on site, Dr Kerner has his eyes on a bigger market. Using special species, algae can be used to produce food and skin products.
After running for almost a year, the system reaches a conversion efficiency (the amount of light hitting the facade converted to energy) of 10% for biogas and 48% for heat, 58% in total.
Over 0.8 million euros was invested by IBA Hamburg to finance the bioreactor facade. All the bioreactors at this demonstration project are made by hand. The cost could be reduced significantly if the bioreactors are mass produced.
BIQ is a showcase of the concept of sustainable and renewable energy while capturing CO2. Apart from serving the conventional purpose of insulating the building from sound, heat and cold, the algae facades produce heat and biomass to supply the building with energy from renewable sources. In the meantime, it removes CO2 and NOx and SOx (as nutrients to algae) from the flue gas.
After seeing the BIQ house, Dr Kerner drove me to the SSC’s pilot site where they are carrying out research on the factors affecting algae growth and to optimise the bioreactors (see photo of facades).
I also had a meeting with Niels Wieczorek and Stefan Syrigos from the Technical University Hamburg at the Innovation Centre Hamburg-Reitrbrook. They introduced their project on the cultivation of microalgae for biomass and biogas production using combustion exhaust gases. This project is subsidised by the Hanseatic City of Hamburg and E.ON Inc. The Innovation Centre was set up as part of this project and is located at an E.ON’s gas power plant.