Although algae compose less than 1% of the Earth’s plant biomass, it is responsible for 45% of the photosynthesis. At approximately 5,000 gallons of oil per acre per year and 12-15 kg of CO2 per gallon of oil, algae photosynthetic efficiency makes it the most prolific producer of oil and consumer of CO2 among plants. The photosynthetic efficiency of algae results in biomass productivity that far exceeds the productivity of other renewable fuel feedstocks, as shown in the following table:
| Renewable fuel feedstock | Biomass productivity (ash free dry weight tonnes per acre per year) |
|---|---|
| Algae | 48 |
| Switchgrass | 8 |
| Sugarcane | 29 |
| Corn | 4 |
| Soy | 1.03 |
| Camelina 0.81 | |
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Source: Falkowski 1994; Field et al. 1998; Sugarcane http://edis.ifas.ufl.edu/AG303 ; Switchgrass http://www.agecon.uga.edu/ ; Corn http://www.ncga.com/ ; Soy http://usda.mannlib.cornell.edu/ ; Camelina http://www.nass.usda.gov/ |
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Not all renewable fuels are compatible with the full network of today’s fuel infrastructure (e.g., ethanol, biodiesel).
To avoid damage to the approximately $12 trillion US network of pipelines, refineries, tankers, gas stations, and vehicles, strict specifications permit only particular hydrocarbon products to flow through the system. Because algae-derived jet fuel, gasoline, and diesel are hydrocarbon products compliant with the existing infrastructure specifications, they are compatible with today’s infrastructure and considered ‘drop-in’ products.
Algae’s superior biomass productivity and ability to produce energy dense hydrocarbon fuels enable it to make a greater impact to the US domestic fuel supply on smaller land area than other highly recognized fuel feedstocks.
| Renewable fuel feedstock | Land area required to displace 15% of US transportation fuel on a Btu basis (MM acres) |
|---|---|
| Algae | 7 |
| Tree farming | 70 |
| Corn | 90 |
| Swithgrass | 90 |
| Corn stover | 150 |
| Forest waste | 500 |
| Source: Calculated on a Btu basis. Assumes all algae is used to produce diesel and all cellulosic processes produce ethanol. CA Air Resources Board, GREET model, 2009; Walters, Yang, “Corn stover removed without compromising soil quality”, Dept. Agronomy & Horticulture, UNL ; Vinod Khosla | |