The U.S. aviation industry consumed ~98 billion liters of fossil jet fuel (worth ~$42 billion) in 2017, which was ~2.3% of the total energy used in the U.S. and caused the same percentage of U.S. greenhouse gas (GHG) emissions. Given the high contribution of aviation industry to energy use and GHG emissions, as well as the recent international commitments to reduce non-renewable energy use and GHG emissions, replacing fossil jet fuel with renewable jet fuel is gaining interest. Several oilseeds, including canola, camelina, soybean, and carinata, have been approved as potential jet fuel feedstocks. Pennycress (Thlaspi arvense L.), a new oilseed crop, has distinctive advantages as a potential jet fuel feedstock, as: (1) it can be planted as winter annual crop in corn-soybean rotation in the Midwestern U.S., without additional land requirement, and provide ecosystem services; and (2) pennycress grain has high oil content (25-36%) with acceptable quality for the conversion to jet fuel. However, feasibility and sustainability of commercial jet fuel production from pennycress has not been evaluated. Thus, the main objective of this dissertation was to evaluate the techno-economics, and life cycle energy and environmental impacts of hydroprocessed renewable jet fuel (HRJ) production from pennycress. The specific objectives included: evaluate pennycress production potential in Ohio and identify the suitable sites for the biorefineries; evaluate the techno-economics of HRJ production from pennycress; and assess the life cycle energy and environmental impacts of HRJ production from pennycress.
Pennycress production potential in Ohio was estimated using a resource assessment model developed using the Geographic Information System (GIS). In addition, the best locations to establish the HRJ biorefineries were identified using location-allocation technique based on the GIS model. A stochastic techno-economic model for pennycress production, harvest and post-harvest logistics, pennycress oil extraction and conversion to HRJ was developed. The HRJ biorefinery capacity was considered based on the U.S. small-scale biodiesel plants, as it is expected that the initial commercial biobased HRJ plants will be of smaller size. The capacity of HRJ biorefinery for this analysis was considered to be 5 MGPY (~18.9 million L/yr (MLPY)) in Ohio. Technical feasibility was evaluated by estimating resources, equipment and facility requirements. Economic analysis included the estimation of capital and operating costs, minimum selling price (MSP), return on investment, and net present value. The net energy gain was evaluated by determining the energy inputs and outputs during its life cycle. In addition, the potential environmental impacts of HRJ production from pennycress were evaluated using the life cycle assessment approach. To test the robustness of the results by incorporating data variabilities, uncertainty analysis was conducted using Monte-Carlo simulations.
Potential land for pennycress production in Ohio was estimated to be ~0.6 million ha, which could annually produce ~1.1 million t pennycress grain as feedstock to produce ~210 MLPY HRJ, depending on the pennycress yield, oil content and conversion efficiencies. In addition, the optimum locations for 12 biorefineries, each at 18.9 MLPY HRJ capacity, were identified. Total cost of production and logistics was estimated to be 170-230 $/t (90% central range (CR)), which was considerably lower than the production and logistics costs of the other competitive oilseeds, such as canola, carinata and camelina; and it was highly sensitive to pennycress grain yield.
The HRJ production cost was highly sensitive to pennycress grain price ($/kg), and production capacity. MSP of HRJ was estimated to be $1.2/L, which was comparable to the MSP of HRJ from similar oilseeds, including camelina and canola; however, it could be further improved by supplying pennycress grain at a lower price, as well as increasing the oil content and biorefinery capacity. Global warming potential of pennycress-based HRJ (35-49 kgCO2eq/GJ HRJ, (90% CR)) was lower than that of petroleum-based jet fuel (89 kgCO2eq/GJ); and it was ~60% less than that of canola-based HRJ production, comparable to that of sunflower (~42 kgCO2eq/GJ), and in the lower range of GHG emissions of renewable jet fuel production from poplar, a lignocellulosic biomass, (32-73 kgCO2eq/GJ). Pennycress production had the highest contribution to the total energy use and environmental impacts, mainly due to the use of nitrogen fertilizer in the field, and fuel for machinery operations.
The outcomes of this study are useful for identifying the key drivers towards sustainable establishment of pennycress-based HRJ production in Ohio and the Midwestern U.S. They contribute to identifying the performance targets needed to reach the viability of pennycress-based HRJ production, which can help the local farmers through making additional economic benefits. The outcomes of this study can also help policy makers identify suitable policies for establishing the energy-efficient and environment-friendly alternative jet fuel, as well as the potential investors to supply pennycress-based HRJ at the competitive price.