Environmental Impacts from Incorporating Ammonia as a Fuel into Diesel Tractors

Abstract

In a project conducted at the University of Minnesota, anhydrous ammonia was tested as a potential diesel fuel replacement. The University has a pilot facility that is capable of producing ammonia using wind energy and water. Thus, there is a potential to reduce the amount of fossil energy being used in agriculture. Using a modified diesel tractor, a system was developed to split (crack) the hydrogen molecules from ammonia and use them in the existing diesel engine. An important aspect in considering the use of ammonia fueled tractor system is the environmental component. Currently, agricultural sustainability is a trending topic and there is significant interest in reducing fossil energy use and greenhouse gas emissions associated with farming. Renewably produced ammonia fuel has the potential to both reduce the amount of fossil energy needed for and greenhouse gas emitted in agriculture. Local production of ammonia would also provide a potential revenue stream for agriculture and rural communities. As part of this project, an exploratory LCA was conducted to examine changes in fossil energy and greenhouse gases when substituting ammonia fuel for diesel fuel in operating a tractor. As a first step, the environmental impacts were examined per kg of diesel fuel replaced. To get a better sense of how this impacts broader agricultural systems, LCA work on corn production impacts was included. The LCA looked at both burden free ammonia (no associated environmental impacts) and the use of ammonia from a grid tied wind farm ammonia production system.