Assessment of Ammonia as an Energy Carrier from the Perspective of Carbon and Nitrogen Footprints

Abstract

Ammonia has been proposed as a promising energy carrier and is expected to play a resilient and sustainable role in future energy scenarios. Energy systems critically impact biogeological carbon and nitrogen cycles. Thus, carbon and nitrogen footprints are two important indicators of sustainability for energy systems. In the present study, we explored the optimal supply pathway and identified impact hotspots by investigating the carbon footprint associated with greenhouse gas emissions and the nitrogen footprint associated with reactive nitrogen emissions from the ammonia energy system. Four scenarios (Japan to Japan, JP–JP; Australia to Japan, AU–JP; Chile to Japan, CL–JP; Saudi Arabia to Japan, SA–JP) were modeled based on international relations and energy distribution between these countries. Compared with the Japan electricity mix, it is a win–win situation under scenario JP–JP from the perspective of carbon and nitrogen footprints, while trade-offs were identified under the scenarios AU–JP and CL–JP. SA–JP performed worse in both carbon and nitrogen footprints. Improvement of key processes is critical to mitigate greenhouse gas and reactive nitrogen emissions. When the efficiency of partial oxidation increased by 25% in SA–JP, the carbon and nitrogen footprint decreased by 17% and 8%, respectively. This evaluation relayed information on the sustainable use of ammonia as an energy carrier by examining the relative impacts on both carbon and nitrogen footprints.

Spatial variation in cost of electricity-driven continuous ammonia production in the United States

“…Ammonia offers some distinct advantages over other energy carriers, such as being carbon-free at point of use, increased volumetric energy density vs. compressed H 2 , ease of storage and transport compared to liquid or gaseous H 2 and long-track record for safe handling at scale. [2][3][4] The predominant route for ammonia production today relies on fossil fuels such as natural gas and coal as a source of energy and hydrogen for thermochemical Haber-Bosch (H-B) synthesis, and is estimated to result in about 2.3 tonnes of CO 2 per tonne NH 3 produced. 5 The reliance on natural gas for ammonia production also implies that cost of natural gas is a key driver of the effective landed cost of the ammonia, ranging from 300-400 $/tonne in the U.S. context 6 to higher prices near 700 $/tonne for other regions with limited domestic natural gas supply and infrastructure constraints, such as India and Africa.…”

Rational Design of Graphene-Supported Single-Atom Catalysts for Electroreduction of Nitrogen

“…Over the past several decades, the rocketing global population and rapid societal development have spurred soaring demand for energy sources. , In this regard, ammonia (NH 3 ) has proven to be vital to human life, because it not only is one of the most important feedstocks for producing fertilizers but also can serve as a pollution-free and efficient energy carrier due to its high energy density induced by its high hydrogen concentration. − Accordingly, human-made methods of NH 3 synthesis have become crucial and meaningful for meeting the demands of rapid societal development. The Haber–Bosch process developed to synthesize NH 3 from N 2 has been regarded as one of the most important advances in the 20th century and is still a principal source of NH 3 , and its optimum performance has been improved in the past few decades.…”

Life Cycle Assessment of Nitrogen Circular Economy-Based NOx Treatment Technology

“…Recent research has been conducted on the conversion of NO to NH 3 for recovery, which was defined as ReNO x [14][15][16]. NH 3 is not only one of the most important traditional sources of fertilizers for agriculture, but is also emerging as a promising energy carrier which might play an important part in future energy scenarios [17,18]. For ReNOx, NH 3 was not used as a reducing agent, but as a product.…”