Algae are simple aquatic plants that range from single-celled microalgae to large seaweeds (macroalgae). There are opportunities to cultivate algal biomass for biofuel production: by extraction of oils directly from microalgae; and by using the algal biomass to feed other conversion technologies such as fermentation and anaerobic digestion.
How can they be used?
Algae can be grown using water resources such as brackish-, sea-, and wastewater unsuitable for cultivating agricultural crops.
Microalgae can be used for carbon storage, reducing carbon dioxide emissions produced by industry; and bio-oil production, which can be used to produce fuel for vehicles or for heating and electricity production. Microalgae can be integrated into wastewater treatment processes to reduce energy and cost associated within cleaning water streams. Microalgae absorb and thrive on nitrates and phosphates and other nutrients common in waste waters. The resulting biomass can be used for a host of applications including as a co-feed for AD, fertiliser for the soil, animal feed and biodiesel production.
Macroalgae (seaweeds) can be harvested from sites with care to avoid negative impacts on the environment or cultivated on lines and then harvested. Macroalgae can be either used for anaerobic digestion, to produce a gas for heating and electricity production or fermented to produce bioethanol which can be used as a fuel.
- Carbon fixation – carbon emission capture.
- Microalgae: Oil yield is higher than oilseed (terrestrial) crops
- Macroalgae: have a faster growth rate compared to terrestrial plants (some species double their biomass within a few hours)
- Does not compete with agricultural land. Land use is minimal and can use land and water unsuitable for anything else.
- No herbicides and pesticides required
- They can be used for fertilisers (they fix nitrogen and phosphate) and animal feed after oil extraction
- Bioremediation applications - can be used to tackle surface run-off from agricultural land and in waste water treatment, where it reduces chemicals and energy input required for cleaning the water. The sludge can then be used for further energy production.
- Can be used as a substrate for energy production: pyrolysis, anaerobic digestion, combustion and biofuel (biodiesel, bioethanol, biobutanol) production.