Algae Reactors - Another way to fuel vehicles
Algae are the
fastest-growing plants in the world. Like other plants, they use photosynthesis
to harness sunlight and carbon dioxide, creating high-value compounds in the
process. Energy is stored inside the cell as lipids and carbohydrates, and can
be converted into fuels such as biodiesel and ethanol. Proteins produced by
algae make them valuable ingredients for animal feed. GreenNRG uses a portfolio of technologies to profitably recycle CO2 from smokestack, fermentation, and geothermal gases via naturally occurring species of algae. Algae can be converted to transportation fuels and feed ingredients or recycled back to a combustion source as biomass for power generation. Industrial facilities need no internal modifications to host a GreenNRG algae farm. In addition, the system does not require fertile land or potable water. What does GreenNRG do? GreenNRG uses a portfolio of technologies to profitably recycle CO2
from smokestack, fermentation, and geothermal gases via naturally occurring
species of algae. Algae can be converted to transportation fuels and feed
ingredients or recycled back to a combustion source as biomass for power
generation. When was GreenNRG founded? GreenNRG, a privately held, venture-backed firm, was founded in 2001 as a subsidiary of Global NRG Ltd. Why
is Global NRG focusing on algae instead of other energy crops like corn? Algae
have some advantages to other energy crops*, specifically: ·
Algae are the fastest growing plants in the world and can be grown year round,
unlike seasonal crops. ·
Algae farming does not require agricultural land or clean water, so it does not
compete with food crops for these resources. ·
While it is difficult to compare one energy crop to another, per hectare of land
algae is more productive than corn, soy or palm. ·
Unlike other energy crops, the entire biomass produced from algae can be used in
end products. ·
Lastly, the algae produced by GreenNRG can be used to produce renewable biofuels
needed to reduce dependence on non-renewable fuel sources such as coal, oil and
natural gas. Algae are
simple organisms that range from very small, single-celled microalgae to
macroalgae that group into very large organisms such as kelp. There are more
than 300,000 species of algae in the Smithsonian Institution collection. The
vast majority of algae are photosynthetic, deriving energy from the sun to
produce energy and biomass.
Yes.
Algae are grown commercially around the world, primarily for nutritional, feed,
and specialty product use. What
is required to grow algae? The primary requirements for growing algae are sunlight,
water, and carbon dioxide (CO2). Algae also require nutrients and
environmental conditions appropriate to the specific algal species. Algae are
known to grow in environments as diverse as the arctic and Does GreenNRG grow algae using the CO2 in our atmosphere? No.
GreenNRG’s technology consumes high concentrations of CO2 (between
5-30%) as it is emitted from power, cement and chemical plants before it is
absorbed into the atmosphere. Atmospheric CO2, at less than 0.04%, is
not concentrated enough to deliver the productivities we are seeking. Does GreenNRG grow algae in open ponds? No.
GreenNRG algae farms are enclosed systems resembling greenhouses. They are often
called algae-solar bioreactors. What
kind of algae does GreenNRG use? GreenNRG selects microalgae based on a number of factors, most notably high innate growth rates, favorable overall composition (lipids, carbohydrates, and proteins), and ability to grow in specific climatic conditions. How
much algae does a GreenNRG algae farm grow? There are
a number of variables including innate growth rate per species and seasonal
availability of sunlight. GreenNRG anticipates that a commercial algae farm will
grow an average of 80 grams of algae per square meter growing footprint per
day.* *See Appendix Photosynthesis at the bottom of the page Do
algae accumulate heavy metals or other harmful substances that may be present in
the CO2 source? No.
GreenNRG only selects algae species that do not accumulate metals or other
harmful substances. In addition, Global NRG has established analytical methods
to confirm the lack of bioaccumulation in initial studies at each host facility
and throughout commercial operations. Does
GreenNRG use algae that have been genetically modified? No.
Global NRG does not use any algae species that are genetically modified
organisms (GMOs). What
products does an algae crop yield? A
GreenNRG algae farm is designed to produce a number of products including algal
oil, delipidated algal meal (DAM) and dried whole algae (DWA). The algal oil is
suitable for conversion to biodiesel and can be substituted for any other
vegetable oil (soy, palm, jatropha) in a commercial biodiesel production plant.
The DAM and DWA are suitable for a wide variety of animal feed applications. How
much oil can be made from algae? Different
species of algae generate different amounts of oil. Global NRG has focused on
several algae species that contain approximately 25% of their weight as oil.
How
does GreenNRG algal meal compare to other meal products? The algae
meal from a GreenNRG algae farm has a high protein content compared to other
animal feed product such as dried distiller’s grains from ethanol production or
soy meal after oil removal.
Energy Crop
Comparisons
Are
there any accurate measures to compare algae to other energy crops? Due to a large number of variables, it is difficult to accurately compare one energy crop to another. Global NRG recommends comparing energy crops based on the final products produced, and the resources required to produce those products. How
are algae different from other energy crops? Algae are different from other energy crops in one significant way--the entire biomass produced from an algae farm can be used in end products that are economically valuable. Unlike comparable crops (corn, sugar cane, rapeseed/canola, palm, soybeans, sunflower, jatropha, etc.) which typically contain a substantial amount of wasted biomass, 100% of algal biomass can be used to create new products. How
does algae productivity compare to other energy crops? Unlike seasonal crops, algae can be grown year round. Since an algae crop does not result in wasted biomass, algae are generally considered to be more productive than comparable energy crops. How
does algae fuel production compare to other liquid fuel crops including corn
ethanol? Under our base design, oil production from the algae farm is estimated at over 5,500 gallons per acre per year. This compares to palm oil at 500, soy at 90, and corn (in the form of ethanol) at 350 gallons per acre per year.
Impact of Algae on CO2,
Water and Other Resources How
much CO2 can algae consume? CO2
consumption is based on the overall lipid/protein/carbohydrates balance of the
final algae. Lipids are typically about 75% carbon by weight, with carbohydrates
approximately 40% carbon by weight, and proteins between the two. GreenNRG
algae is approximately 50-55% carbon by weight; about 1.9 times the biomass
weight in CO2 is required to generate algae with this composition. If
algae with a higher lipid content is produced, that ratio will be higher; the
higher the carbohydrate composition, the lower this ratio. What
is the maximum CO2 consumption per acre of a GreenNRG algae farm? ** A
GreenNRG algae farm will consume approximately 500 metric tons of CO2
per hectare per year based on current algae composition and growth rates. How
much of the CO2 from an industrial facility can a GreenNRG algae farm
consume? The
current design of a GreenNRG farm can mitigate a maximum of 40% of the emissions
from a round-the-clock operation. How
large must an algae farm be to mitigate emissions from a typical power plant? ** Based on
information in the US Energy Information Administration 2006 power plant
database, for the approximately 500 power plants in the How
much water does a GreenNRG algae farm require? Because GreenNRG’s algae farm is a closed system, overall water use is minimal and evaporation losses are limited. Some water is required for the photosynthesis reaction, and some is lost in the creation of algal products. Where available, water may also be used for system cooling based on site-specific dependencies. Does
GreenNRG’s system produce agricultural (nutrient) runoff? No. GreenNRG’s algae farms are enclosed and nutrients are recycled to make the most efficient use of resources. Can
the GreenNRG system use feed water streams that are high in nutrients such as
phosphorous and nitrogen? Global
NRG is actively pursuing several opportunities where nutrient-rich water feed
streams will be used to provide some or all of the nutrients needs of the algae
farm. Streams which have a potential to be used in this way include runoff from
animal facilities and treated wastewater.
*PHOTOSYNTHESIS
Photosynthesis is the process by which plants utilize the energy in the sun’s
rays to produce energy and new plant matter (biomass). Photosynthesis is the
base reaction supplying the vast majority of energy used by plants and animals
on earth. In photosynthesis, energy (photons) from the sun’s rays converts
carbon dioxide and water to carbohydrate plus oxygen. The carbohydrate can be
converted to protein or fat.
Solar
energy is spread along a wide range of wavelengths, of which only a portion is
useable for photosynthesis. The wavelengths useable by plants are known as
photosynthetically active radiation (PAR), and include about 45-50% of the total
solar energy. Energy requirements of the photosynthesis reaction reduce the
usability of that 45-50% by another factor of 4, making the theoretical energy
use roughly 11% of the overall solar energy.
This
photosynthetic efficiency is translated into biomass including fats, proteins,
complex carbohydrates (cellulose, lignin, etc.) and simple carbohydrates. Also,
most crops contain water. To eliminate the effect of water, we present values
based on dry biomass. We also need to understand that production of other
compounds from simple carbohydrates requires some of the energy.
We have
grown algae at a photosynthetic efficiency of approximately 5.4% under natural
sunlight. General crops grow at a photosynthetic efficiency of approximately 1%.
Algae can be grown much more efficiently because of the nature of the bioreactor
and the removal of factors that might limit growth such as lack of nutrients or
CO2.
You can
also improve algae growth by using artificial lighting. Algae will grow 24 hours
per day if there is sufficient light. However, due to the energy losses inherent
in each step from generating electricity to create light and using the light for
photosynthesis, this is not economical for anything other than studies, unless
the value of the final product is very high (as it is for some commercial algae
farms where artificial light is used).
Based
on actual meteorological data from the ‘Typical Meteorological Year’ data (TMY)
for Phoenix, Arizona, the average hour by hour Global Horizontal Direct and
Diffuse solar radiation is 242 W/m2 (across 24 hours, 365 days), which converts
to 5.81 kWh/m2-day (242 * 24 hours * 1000 kW/W). From the NREL solar database
the average is 5.7 kWh/m2-day.
Using
the lower value of 5.7 kWh/m2-day, the total energy on a yearly basis is 2080.5
kWh/m2-yr. At 1 kWh = 3.6 million Joules, and 1 Joule = 0.002388 kCal, this is
equivalent to 2080.5 * 3.6 * 10^6 * 0.0002388 = 1.79 * 10^6 kCal/m2-yr
At 11%
maximum theoretical photosynthetic efficiency, 1.97 * 10^5 kCal/m2-yr is
available for photosynthesis, which is sufficient to create 51.6 kg/m2 glucose.
The
energy required to fix 1 mole of CO2 via photosynthesis is 114 kCal,
or 686 kCal per mole of glucose created. 1 mole of glucose is 180 grams, so 1 Kg
of glucose (as biomass) requires 3811 kCal of solar energy. Our proven
productivity of 98 g/m2-day dry biomass at our Arizona facility in 2007 is
equivalent to 36 kg/m2-yr productivity, which is 70% of the theoretical maximum,
or a photosynthetic efficiency of approximately 7.7%. Since these results were
achieved during the summer, when peak solar radiation is experienced, we would
expect the annual average productivity to be somewhat lower. In fact, using the
average monthly solar radiation of 8.0 for June and July in
**Facility Size We generally assume that the growing areas of the algae farm will be available for growing algae 85% of the year. Similarly, the annual average productivity is estimated at 80 gm/m2-day for our highest productivity system. Thus the overall system productivity is about 25 kilograms per square meter per year (55 pounds). The overall biomass is expected to be slightly over 50% carbon by weight. Since carbon is 27.3% of the weight of CO2, it requires approximately 1.9 times the weight of produced biomass in CO2. Thus for every 1 ton of biomass produced, 1.9 tons of CO2 are consumed. Multiplying 55 * 1.9 = 104.5 pounds CO2 consumed per square meter growing area per year.
Our
standard commercial algae farm includes 100 hectares (247 acres) of algae
growing area, which will consume over 52,000 The algae farms are expected to be built in multiple units of the 100 hectare standard for facilities where more CO2 is available. |