The need for Sustainable Energy “Global energy needs are expected to grow, with fossil fuels remaining the dominant source and sharply pushing up CO2 emissions. On our current trajectory, the global temperature could increase by 6° C by 2100 with dramatic implications for all countries. Energy security and climate change are global concerns and require global solutions. The challenge for all countries is to put in motion a transition to a more secure, lower-carbon energy supply and demand, without undermining economic growth. An energy technology revolution is needed to set us on a more sustainable energy path.”
Report from the IEA: Energy Technology Perspectives 2008
Report from the IEA: Energy Technology Perspectives 2008
What are algae?
Algae are a hugely diverse group of organisms, most of which are autotrophic through photosynthesis and growing predominantly in aquatic environments. Their size can vary from a single- or multi-cellular organism (micro-algae) to giant sea kelps (macro-algae) which can reach lengths of over 60 meters. Algae tend to be biologically "simple" and can grow quickly since they lack the complex tissue arrangements that form organs in land plants.
Foodchain
Autotrophic organisms, like algae, serve as the primary producers in the global foodweb. The biomass productivity (i.e. the total mass of autotrophic organisms produced each year) in limnic ecosystems accounts for 1.5% of global net primary production. Much of this algae is encouraged by eutrophication, and at such high concentrations is considered a nuisance (see The Problem).
Use & Potential
Algae has been identified as providing a potential solution to a host of problems. These uses include:
Algae are a hugely diverse group of organisms, most of which are autotrophic through photosynthesis and growing predominantly in aquatic environments. Their size can vary from a single- or multi-cellular organism (micro-algae) to giant sea kelps (macro-algae) which can reach lengths of over 60 meters. Algae tend to be biologically "simple" and can grow quickly since they lack the complex tissue arrangements that form organs in land plants.
Foodchain
Autotrophic organisms, like algae, serve as the primary producers in the global foodweb. The biomass productivity (i.e. the total mass of autotrophic organisms produced each year) in limnic ecosystems accounts for 1.5% of global net primary production. Much of this algae is encouraged by eutrophication, and at such high concentrations is considered a nuisance (see The Problem).
Use & Potential
Algae has been identified as providing a potential solution to a host of problems. These uses include:
- Bioenergy production, replacing fossil fuels.
- Water pollution remediation, as a low energy treatment.
- Carbon capture, storing carbon from photosynthesis.
- Landfill management, taking up and thereby 'fixing' harmful leachates.
- Feed production for humans (currently its main use) and livestock.
Read more on Biocrops from the Biomass Energy Centre
Cultivation methods - Monoculture vs. Polyculture
Currently there are two main methods for growing algae...
Currently there are two main methods for growing algae...
|
Open Ponds are considered the cheapest method of producing algae, but yields are limited by vulnerability to contamination by competing or predator species, and exposure to sub-optimal weather conditions. This method is nearly always used to cultivate Polycultures, though Monocultures can be achieved using algae species that grow in extreme conditions like saltwater, thereby eliminating competing organisms.
Raceway pond used for the cultivation of microalgae. The water is kept in constant motion with a powered paddle wheel. Photograph by JanB46 of Wikimedia Commons, CC Share-Alike License
|
Photo-bioreactors are more expensive to run and maintain than open ponds, with high energy and cost input needed to provide optimal growth conditions for a monoculture. The need to cool and mix the water, control oxygen accumulation and prevent biofouling are disadvantages of PBRs, though contamination, water evaporation and carbon dioxide losses are minimised. Tubular or flat plate system are used.
Tubular photo-bioreactor containing algae.
Photograph from BioShark Technology Product Brochure.
|
