Gas from Algae, Pros & Cons
Researchers think algae might be part of the answer to slowing greenhouse gas emissions at power plants, and ultimately climate change.
Not only for cars, algae can also heath buildings like this German Office.
To create the algae façade, the building is covered in bio-reactive “louvers” that enclose the algae. Additionally, the bio-reactors trap the heat energy created by the algae, which can then be harvested and used to power the building.
Tiny ‘micro-algae’ plants, most no larger than bacteria, are continuously supplied with liquid nutrients and carbon dioxide via a water circuit. With the aid of sunlight, the algae photosynthesize and grow until they can be harvested. They are then separated from the remaining algae and transferred to the energy management center as a thick pulp where they are fermented to provide bio-gas which can be used to heat water.
The benefits of algae have been shown to extend beyond biomass fuel, and into pollution-detection and carbon dioxide-absorption combined with oxygen release.
New photo bio-reactors
Algae was initially raised in large shallow ponds which produced about 5,000 gallons per acre-year and required a fair amount of water to compensate for evaporation. More recently, companies have migrated to vertical photo bio-reactors:
- gravity fed
- no evaporation
- 85% of the water is recycled along with excess nutrients and CO2
As algae have a harvesting cycle of 1–10 days, their cultivation permits several harvests in a very short time-frame. There are 3.8 million hectares of fish farm water surfaces in China alone. That is enough space at full production to supply daily domestic demand. Imagine if every country used all of their water surface space to produce algal fuels, imports would be drastically reduced across that globe.
- Truly renewable, bio-based fuel: carbon neutral
- Higher energy per-acre than other bio-fuels
- Absorbs carbon dioxide as it grows
- Both waste CO2 and wastewater can be used as nutrients
- Production is scaling up
- Need to be grown under controlled temperature conditions
- Harvesting algae is a challenge
- Requires phosphorus (scarce) as a fertilizer and the fertilizer production is carbon dependent
- Expensive investing costs
Decreasing water rate is needed
Algae oils have a variety of commercial and industrial uses, and are extracted through a wide variety of methods including using centrifuge, micro-screens, flocculation, and ultrasound. Microalgae grow suspended in large volumes of water; at harvest time, there may be as 1,000 times more water than algae, or more.
This must be reduced to roughly a 10:1 ratio before the algae is useful for commercial applications. Costs have been high, because existing dewatering processes rely on chemicals or on heavy equipment, or both. Estimates of the cost to extract oil from micro algae vary, but are likely to be around $1.80 (US$)/kg (compared to $0.50 (US$)/kg for palm oil) by means other than ultrasonic separation.
More renewables, pros & cons
- Tidal Wave Energy, Pros & Cons
- Gas from Algae, Pros & Cons
- Biomass Power, Pros & Cons
- Hydrogen Power, Pros & Cons
- Shale Gas, Pros & Cons
- Solar Power Pros & Cons
- Energy from Tar Sands Oil, Pros & Cons
- Fusion Power, Pros & Cons
- Wind Energy Pros & Cons
- Geothermal Energy, Pros & Cons
- Concentrated Solar Power, Pros & Cons
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