Chukwuemeka Valentine Okolo

This study examines the long‐run determinants of ethanol carbon intensity (CI) under Oregon's Clean Fuels Program (CFP). The study emphasizes how biofuel costs, credit market dynamics, and electric vehicle (EV) infrastructure interact to shape low‐carbon transitions. Using monthly data from 2018 to 2024, we apply a set of econometric techniques, including fully modified ordinary least squares (FMOLS), instrumental variables (IV‐2SLS), dynamic OLS with robust and quantile estimators, bootstrap simulations, and nonlinear specifications, to ensure rigorous and reliable inference. The results reveal three central findings. First, average credit prices are consistently linked to reductions in ethanol CI. This confirms the fundamental role of market‐based incentives in driving decarbonization. However, this relationship is nonlinear: Compliance responses strengthen with moderate credit increases but taper at higher price levels. Second, biodiesel (B5) and ethanol (E10) costs are associated with lower ethanol CI. This reflects the CFP's performance‐based structure, where rising costs coincide with stronger credit generation and cleaner fuel blending. Third, the expansion of EV infrastructures, such as DC fast‐charging infrastructure, supports additional CI reductions, though with diminishing marginal gains as network density increases. Interaction analysis further shows that credit prices are most effective in areas with more developed EV infrastructure. This underscores the combined effect between market signals and technological deployment. Therefore, the research findings demonstrate that Oregon's CFP effectively integrates economic incentives and infrastructure investment to advance sustainable, low‐carbon transportation fuel transitions.

This study investigates the long-run determinants of ethanol carbon intensity (CI) under Oregon’s Clean Fuels Program (CFP), with a focus on the relationship between biofuel costs, credit market dynamics, and electric vehicle (EV) infrastructure. Using monthly data from 2018 to 2024, we apply a set of econometric techniques, including fully modified ordinary least squares (FMOLS), instrumental variables (IV–2SLS), dynamic OLS with robust and quantile estimators, bootstrap simulations, and nonlinear specifications. The results reveal three key dynamics. First, CFP average credit prices consistently reduce ethanol CI. This reinforces the central role of market-based incentives. This effect, however, is nonlinear: while moderate credit price increases yield strong compliance responses, marginal returns diminish at higher values. Second, the costs of diesel (B5) and gasoline (E10) are negatively associated with ethanol CI. This reflects the program’s performance-based design, where higher costs often signal stronger credit generation, tighter supply, and cleaner blending strategies. Third, EV infrastructure, particularly DC fast charging (DCFC), significantly reduces ethanol CI, though with diminishing marginal benefits at higher levels of deployment. An interaction analysis further demonstrates that credit prices are more effective in reducing CI when EV infrastructure is more developed. This underscores the synergy between market signals and infrastructure expansion. These findings highlight the effectiveness of Oregon’s performance-based clean fuel standard in mobilizing multiple compliance pathways. The results support a balanced policy mix that stabilizes credit markets, safeguards biofuel supply, and accelerates EV infrastructure deployment. By demonstrating robust and nonlinear drivers of CI reduction, this study provides important insights for states and regions seeking to design integrated, adaptive, and low-carbon fuel policies.

U.S. gasoline and diesel prices are often volatile, driven by geopolitical risks and disruptions in the fossil fuel market. Forest biomass fuels, particularly renewable diesel derived from logging residues, offer a low-carbon alternative with the potential to stabilize fuel prices. This study evaluates whether biomass can moderate fuel price volatility using ANOVA, Tukey post hoc tests, and quadratic regression based on monthly data for biomass production, inventories, and retail fuel prices. Findings reveal the existence of a significant nonlinear relationship between forest biomass inventory levels and fossil fuel prices. Average gasoline prices peaked in the medium-inventory group (M = 0.837) and dropped in the high-inventory group (M = 0.684). Diesel prices followed a similar pattern, with the highest values in the medium-inventory group (M = 0.963) and the lowest in the high-inventory group (M = 0.759). One-way ANOVA results were statistically significant for both gasoline (F(2, 99) = 7.39, p = 0.001) and diesel (F(2, 99) = 7.22, p = 0.0012). Tukey tests confirmed that diesel prices fell significantly from both medium to high and low to high-inventory levels. This result remains robust when using the biomass index level and the biomass production level. These results indicate a threshold effect: only at higher biomass inventories do fossil fuel prices decline, suggesting a potential for substitution. However, current policies inadequately support biomass integration, highlighting the need for targeted reforms.

Decarbonizing Oregon’s heavy-duty trucking sector, which accounts for 24% of the state’s transportation emissions, is essential for meeting carbon reduction targets. Drop-in fuels such as renewable diesel, biodiesel, and synthetic fuels provide an immediate and effective solution, reducing emissions by up to 80% while utilizing the existing diesel infrastructure. In 2023, Oregon’s heavy-duty trucks consumed 450 million gallons of diesel, with drop-in fuels making up 15% of the fuel mix. Renewable diesel, which is growing at a rate of 30% annually, accounted for 10% of this volume, thanks to incentives from Oregon’s Clean Fuels Program. By 2030, drop-in fuels could capture 40% of the market, reducing CO₂ emissions by 3.5 million metric tons annually, assuming continued policy support and advancements in feedstock sourcing. Meeting the projected demand of 200 million gallons annually and securing sustainable feedstock remain critical challenges. Advances in synthetic fuels, like Power-to-Liquids (PtL) from renewable energy, may further contribute to decarbonization, with costs expected to decrease by 20% over the next decade. Oregon aims for a 50% reduction in emissions from heavy-duty trucks by 2050, using a mix of drop-in fuels and emerging technologies. While hydrogen fuel cells and electric trucks face challenges, innovations in infrastructure and vehicle design will be key to the success of Oregon’s long-term decarbonization strategy.