Particularly within the last few years, the great potential of micro organisms has been discovered. Josef Plank from the Austrian biomass association describes the production of micro-algae as a key technology: "In 2007 experiments in Arizona have shown over a period of three weeks that under optimal conditions micro algae cultures save 10-25 times more solar energy than plants with roots. Up to 10% of the irradiating solar energy is transformed into biomass. Land plants only use 0.5-1% of the solar energy for the production of biomass. While for micro-algae the yield for one hectare would be 200-400t, the yield per hectare of other plants would only be 10-30t."
Since the middle of the last century, large ponds are used in the US and Southeast Asia to grow micro-algae. The first and largest bio-reactor was built in Klötze/Germany in 1999. This facility is about 1.2 hectares large and has a volume of 600.000 litres in form of a 500km long system of glass tubes.
Today several products are already made with the help of micro-algae. They are used in the production of dietary supplements and some basic elements of the chemical industry, in pharmaceuticals, in the production of cosmetics and additives for farming and aquacultures.
Like any other plant micro-algae need nitrogen. All of the existing bio-reactors need nitrogen to fertilise the cultures. However, no one seems to have thought of using the micro-organisms themselves for the production of nitrogen. In such a case, the cyanobacteria could not only supply themselves with this essential element, but also fix considerable amounts of it. This was our motivation: we wanted to find out, whether cyanobacteria could fix atmospheric nitrogen effectively enough to be an economically viable fertiliser.