Lifecycle analysis of Amyris renewable jet from sugar cane finds “substantial potential” to mitigate GHG emissions, but a wide range of potential outcomes
25 November 2014
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| Monte Carlo results for the net life cycle emissions of the renewable jet fuel from sugar cane. Credit: ACS, Moreira et al.. Click to enlarge. |
Brazilian researchers evaluating the lifecycle GHG emissions of a renewable jet fuel produced from sugar cane in Brazil using Amyris’ proprietary technology platform (earlier post) found that the farnesane-based renewable fuel presents “a substantial potential” to mitigate the GHG emissions of the aviation sector. Their paper is published in the ACS journal Environmental Science & Technology.
In their base case, the researchers calculated a “rather optimistic” GHG footprint of 8.5g CO2eq/MJ; lifecycle emissions of fossil jet fuel usually lie within the 80−95g CO2eq/MJ range. However, they noted, the estimation is highly uncertain, with a number of factors—especially related to electricity exports, sugar cane farming itself, and agrochemicals production and use—significantly affect the outcome. The results of the Monte Carlo analysis indicate life cycle emissions of 21 ± 11 g CO2eq/MJ (mean ± SD), with substantial influence from the LUC factor.
The lifecycle analysis included the direct and indirect emissions associated with sugar cane production and fuel processing, distribution, and use for a projected 2020 scenario. The Brazilian team used the CA-GREET model as the basic analytical tool, while Land Use Change (LUC) emissions were estimated employing the GTAP-BIO-ADV and AEZ-EF models.
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| Farnesane is the renewable hydrocarbon molecule that will compose the renewable jet fuel. The production pathway comprises the fermentation of plant sugars into farnesene (a 15-carbon long-chain branched hydrocarbon that Amyris labels as “Biofene”) using specialized yeasts developed by Amyris. The farnesene forms a separate phase on the top of the fermentation broth, hence facilitating subsequent recovery and purification. The farnesene produced at the sugar cane processing plant is then transported to a hydrogenation plant where it is converted to farnesane, a hydrocarbon molecule. The farnesane is then transported to the airport fuel tanks in Brazil to be blended with regular jet fuel. Credit: ACS, Moreira et al. Click to enlarge. |
Feedstock production and LUC impacts were evaluated as the main sources of emissions, respectively estimated as 14.6 and 12 g CO2eq/MJ of biofuel in the base case. However, the renewable jet fuel strongly benefits from bagasse and trash-based cogeneration.
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| Sensitivity analysis of the renewable jet fuel life cycle emissions. Credit: ACS, Moreira et al.Click to enlarge. |
The study was supported financially by IDB, Boeing, and Embraer, with technical support from Amyris.
Amyris’ first purpose-designed, industrial-scale Biofene plant is located in southeastern Brazil, in the state of São Paulo. The Amyris production unit at Brotas is adjacent to an existing sugar and ethanol mill, Paraíso Bioenergia, significantly reducing the capital required to establish and scale manufacturing.
Amyris has also advanced construction of what will become its second production site in Brazil, located at the São Martinho sugar and ethanol mill also in the state of São Paulo.
Resources
Marcelo Moreira, Angelo C. Gurgel, and Joaquim E. A. Seabra (2014) “Life Cycle Greenhouse Gas Emissions of Sugar Cane Renewable Jet Fuel,” Environmental Science & Technology doi: 10.1021/es503217g
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