Alternative Uses for Algae
Produced For Photosynthetic
CO2 Mitigation
by
Louis Landesman, Ph.D
Increase in Atmospheric CO2
Burning coal to generate electricity releases
large amounts of CO2, a gas that contributes to
global warming and ocean acidification.
Algae can capture this CO2 to produce large
amounts of algal biomass. This biomass contains
oils which can be converted into biodiesel fuel.
The residue remaining after oil extraction is
valuable and its use can make the whole process
more profitable.
Advantages of Algae over Other
Crops as an Energy Source
 Algae can use waste gases from power
plants and industries
 Algae are an order of magnitude more
productive than terrestrial crops
 Algae can grow on salt, brackish or
wastewater
Advantages of Algae over Other
Crops for Producing Biodiesel
 Algae can be harvested every day instead of
just once or twice a year
 Algae can be raised on land unsuitable for
food crops
 Algae can use water not suitable for
irrigation (salt and brackish water)
 Algae require less land to produce an
equivalent amount of biofuel
Algae – a very diverse group
Productivity of Algae as a Crop
 In Arizona Green Fuel’s bioreactors produce up to
25 g dry biomass per square meter per day
 At this rate one hectare could yield around 50
metric tons of dry algae per hectare per year
(22 short tons per acre per year).
 For every one ton of biomass produced, 1.9 tons of
CO2 are consumed.
 Significant quantities of algal biomass and algal
residual products will become available as algae
production increases.
Methods of Algae Production
 Open raceways – Here algae are raised
outdoors in lined or unlined ponds.
Advantages: Low capital cost, easy to
scale up to large areas.
Disadvantages: Vulnerability to disease
and grazing by predaceous animals
(zooplankton, fish and other herbivores).
Pond Culture of Algae – Arizona
Desert Sweet Biofuels – Gila Bend, Arizona
HR Algae Farm, Hawaii
Earthrise Spirulina Farm,
Imperial Valley, California
Methods of Algae Production
 Bioreactors – Here algae are raised in
glass or plastic tubes.
Advantages: Production approaches
theoretical maximum, reliable and
convenient harvest.
Disadvantages: Very high capital cost,
management intensive.
Greenfuel Bioreactors on Rooftop
Algaetech Bioreactor – Israel
Astaxanthin Production - Kibbutz Ketura, Israel
Intensive Algae CultureCarlsbad, New Mexico
Algal slurry ready for harvest
Harvested Algae
Harvested Algae
Algae Farm, Spring Grove, VA
Algae Farm, Spring Grove, VA
Algae as Animal Feed
The most direct use of
the solid residue left
when lipids and
carbohydrates are
extracted from algae
is as animal feed.
Dietary carotene effects on egg yolk color
– Seambiotic, Israel
Control
Omega3
fish oil
Seambiotic
microalgae
powder A
Seambiotic
microalgae
powder B
Algae as Animal Feed
Microalgae has been used in feed for pigs,
poultry, cattle and fish.
Chemicals from Algae
 Carotenoids – xanthophyll, astanzanthin, beta-
carotene. Pigments for food and livestock feed.
 Natural dyes and pigments used in cosmetics and
food coloring (phycocyanin, phycobiliprotein).
 Polyunsaturated fatty acids used for food
supplements.
 Drugs – cholesterol lowering compounds, immune
system stimulants.
 Stable isotope biochemicals and serum
replacement in tissue culture.
Summary
 Residual algal solids remaining after oil
extraction are a valuable source of plant
protein for livestock and fish.
 However the high nucleic acid content and
presence of toxic compounds in some
species of micro-algae may limit the amount
of algae residue that can be used in animal
feed.
Summary II
 Residual algal bio-solids are a source of
new food products and drugs.
 Efforts must be made to isolate, test and
market these algal products.
 These algal-derived compounds could make
CO2 sequestration of algae profitable even if
the price of algal derived biodiesel goes
down.