Applied Energy 92 (2012) 92–98 Contents lists available at SciVerse ScienceDirect Applied Energy journal homepage: www.elsevier.com/locate/apenergy A life cycle assessment of biodiesel derived from the ‘‘niche filling’’ energy crop camelina in the USA ⇑ Brian J. Krohn , Matthias Fripp Oxford University, Environmental Change Institute, School of Geography and the Environment, South Parks Road, Oxford OX1 3QY, UK article info abstract Article history: Camelina sativa (L.) is a promising crop for biodiesel production that avoids many of the potential pitfalls Received 19 July 2011 of traditional biofuel crops, such as land use change (LUC) and food versus fuel. In this study the environ- Received in revised form 30 September 2011 mental viability of camelina biodiesel was assessed using life cycle analysis (LCA) methodology. The LCA Accepted 14 October 2011 was conducted using the spreadsheet model dubbed KABAM. KABAM found that camelina grown as a Available online 29 November 2011 niche filling crop (in rotation with wheat or as a double crop) reduces greenhouse gas (GHG) emissions and fossil fuel use by 40–60% when compared to petroleum diesel. Furthermore, by avoiding LUC emis- Keywords: sions, camelina biodiesel emits fewer GHGs than traditional soybean and canola biodiesel. Finally, a sen- Life cycle assessment sitivity analysis concluded that in order to maintain and increase the environmental viability of camelina Camelina Biodiesel and other niche filling biofuel crops, researchers and policy makers should focus their efforts on achieving Land use change satisfactory yields (1000–2000 kg/ha) while reducing nitrogen fertilizer inputs. Biofuel Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction To address these two issues a variety of alternative biofuel feed- stocks are currently being researched. Niche filling crops show po- Due to a persistent and growing awareness of the negative so- tential in avoiding the two major issues of food vs. fuel and LUC cial, political, and environmental impacts of fossil fuels over the because they are crops that can be grown during fallow periods last two decades there has been a constant push by governments, or mixed into the traditional agricultural system. [8–11]. Camelina industry, and citizens to develop alternative energy sources that sativa (L.) is a niche filling oilseed crop that shows potential as a fu- are both domestic and renewable. In the US biofuels are predicted ture feedstock for biofuels, specifically biodiesel [12,13,13–17]. to make up 80% of the growth in liquid fuels between 2010 and Camelina is a notable potential niche filling crop because com- 2035 [1]. Biofuels from traditional food crops such as corn, soy- pared to current oilseed crops, specifically canola, it requires lower beans or canola, however, have two significant drawbacks. First, agricultural inputs, is more tolerant of cool weather, has a shorter the high demand for biofuel crops may result in direct or indirect growing season, and is more efficient in its water use [14,18–20]. changes in land use on a domestic or international level [2,3]. Land Due to these unique properties camelina is well suited to fill fallow use change (LUC) is a considerable issue when land with a large periods in dryland wheat farming or to be grown as a double crop amount of stored carbon, such as forests or peat bogs, is converted with short season soybeans or sunflowers [18,21–23]. Before con- into land with low amounts of stored carbon as is the case for most siderable acreage is devoted to camelina, however, it is important agricultural land. The resulting conversion releases sequestered to assess its environmental viability. In this paper we assess the carbon into the atmosphere creating a ‘‘carbon debt’’ that may take fossil energy consumption and greenhouse gas (GHG) emissions the biofuel years if not hundreds of years to pay off [2,4,5]. The sec- of camelina biodiesel using life cycle analysis methods. ond issue for biofuels is the dilemma between food and fuel [6].In 2006/2007, food prices around the world reached record highs while the US converted a record 20% of its corn crop to ethanol 2. Methods [7]. With an increasing global population and increasing demand for high agricultural intensity foods such as meat it seems prudent 2.1. Goal and scope to reserve arable land and crop production for food. The methodology of this study follows the ISO 14040 methods for conducting an attributional LCA [24–26]. The goal of this study ⇑ Corresponding author. Address: Keble College, Oxford University, Oxford OX1 is to assess the life cycle energy balance and GHG emissions associ- 3PG, UK. Tel.: +44 909414570. ated with biodiesel derived from camelina in several different sce- E-mail address: [email protected] (B.J. Krohn). narios. The scope of the study includes the agricultural production 0306-2619/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.apenergy.2011.10.025 B.J. Krohn, M. Fripp / Applied Energy 92 (2012) 92–98 93 of the fuel crop, extraction of the oil, conversion of the oil to biodie- sel, and transportation of biodiesel to market. To quantify and compare the energy and emissions in an adapt- able and transparent manner we developed Krohn’s Alternative Biodiesel Analysis Model (KABAM). KABAM uses a similar structure as the attributional LCA models BESS, EBAMM, and GBAMM, which utilize a fixed life cycle energy or emission factor for each input. The life cycle factors were derived using the GREET model and the current LCA literature [27–29]. The life cycle energy and emis- sions factors for each input can then be multiplied by their usage and then summed together to determine the LCA value for the bio- diesel system, as shown in Eq. (1). The benefit of the life cycle fac- tor method is that the assumptions for each input can be easily compared across scenarios and against other models; thus making the model more transparent and allowing for easier review and cri- tique of the models assumptions [30]. X LCA value ¼ ðEmission factorÞx ðUsage rateÞx x ¼ Input into the biofuel system ð1Þ To draw further conclusions from the KABAM model, we also conducted a sensitivity analysis. A sensitivity analysis is a helpful tool because it identifies and ranks the inputs that have the great- est influence on the model’s outcomes. Specifically, a sensitivity Fig. 1. The system boundaries for the life cycle assessment of biodiesel fuel. analysis aids in drawing conclusions from an LCA model by high- lighting the inputs of greatest concern. Sensitivity is evaluated by the sensitivity coefficient, which is defined in finite terms as the change in output from two model runs over the change in a single 2.3. Emission factors variable, see Eq. (2) [31]. The following section describes the data, data sources, and C2 À C1 methods used to determine the life cycle factors for each input used S ¼ ð2Þ k2 À k1 in the KABAM model. The life cycle factors describe the upstream energy or emissions of the inputs, such as fuels (e.g. gasoline) where S is the sensitivity, C the model output, and k is the model and chemicals (e.g. methanol). We utilized GREET’s life cycle path- input. ways to calculate most of the upstream energy and emissions for Finally, a significant issue in all LCAs is how to distribute the en- each input for the year 2010, unless otherwise noted [37]. In some ergy and emissions between the primary product (biodiesel) and instances GREET was insufficient or out of date, in which case we the co-products (glycerin and seed meal) [32]. Allocation methods utilized existing industry data or previous LCA studies to deter- distribute life cycle emissions and energy by numerical properties, mine the life cycle factors, for greater details see the supplemen- such as mass, energy content, or economic value [33]. Another tary material. The greenhouse warming equivalence factors for a method, called displacement, addresses the co-product issue by 100-year period for CO2,CH4, and N2O are 1, 25, 298 respectively, taking account of the energy or emissions that are avoided when were taken from the IPCC 2007 AR4 report. Table 1 lists the fossil the co-products replace other products in the market and thus gen- energy life cycle factors and Table 2 lists the emission life cycle fac- erating an offset credit [33]. The displacement approach is recom- tors for each input used in KABAM. mended by the LCA guidelines issued by ISO 14040-14049, however, it significantly increases the scope of the study [26,34]. Biofuels LCAs have shown considerable sensitivity to the choice of allocation method [35,36]. We address this issue in KABAM by Table 1 Fossil energy life cycle factors for KABAM’s inputs. using the energy and economic value allocation methods as well as the displacement method and comparing the three results. Input Fossil energy per Ref. unit of input Nitrogen MJ/kg 47.70 GREET 1.8c [37] 2.2. System boundary and functional unit Phosphorus MJ/kg 13.35 GREET 1.8c [37] Potassium MJ/kg 8.09 GREET 1.8c [37] The system boundary is defined by the direct inputs into each Lime MJ/kg 0.42 GREET 1.8c [37] and data from [38] Herbicide MJ/kg 274.63 GREET 1.8c [37] stage of biodiesel production. Fig. 1, shows the system boundaries Insecticide MJ/kg 313.46 GREET 1.8c [37] and the general type of life cycle inputs considered in this study. Seed MJ/kg 2.35 Calculated using method from [38] The functional unit of KABAM is one unit of energy of biodiesel Gasoline MJ/L 39.52 GREET 1.8c [37] produced from the system.