Vertical growth/closed loop production has been developed by biofuel companies to produce algae faster and more efficiently than open pond growth. With vertical growing, algae are placed in clear plastic bags/tubes, so they can be exposed to sunlight on all sides. The extra sun exposure increases the productivity rate of the algae, which in turn increases oil production. The algae are also protected from contamination due the closed envionment of their growth.
This small scale experiment shows the growth of algae in a clear plastic tube of rainwater exposed to sunlight. An air pump is used to circulate the algae solution and to provide ample ‘dirty’ air including carbon dioxide. The rainwater provides nutrients such as nitrogen and phosphorus also required for algae growth. It can be seen that algae grows rapidly – in a matter of days – unlike seasonal crops.