Concept and Design Optimization of a Novel Ammonia-Based System for Food-Energy-Water Sustainability

This paper proposes a novel ammonia-based system for food-energy-water sustainability (ABFEWS). This integrated system uses renewable energy and agricultural waste to produce ammonia both as fertilizer and as fuel for tractors and grain drying, to meet local electrical power demands and to provide predictable, consistent power export to the grid. It also extracts and purifies soil water to simultaneously reduce process water imports and drainage to surrounding water ecosystems. The conceptual design of this system exploits synergies between local ammonia production, agriculture, energy supply, and water management to allow for economic viability, specifically time-varying chemical production, ammonia and hydrogen as energy storage media, and the recycle of agricultural waste and soil water. A model for combined optimization of the ABFEWS design and its inherently time-varying operating schedule is proposed with a view on further improving economic competitiveness. A case study which considers the use of two 1.65 MW wind turbines and 196,000 kg of corncob biomass to meet ammonia fertilizer and fuel demands for a 400-acre corn and soy farm and power demand at an adjacent university campus demonstrates the promise of the ABFEWS system and the associated design-scheduling optimization framework. The annualized net present cost of the optimal ABFEWS system is approximately $56,500, which corresponds to an emissions reduction cost of $12.90/tonCO₂. The implementation of the ABFEWS system annually prevents 477 m³ of water import, 558,000 m³ of cooling water discharge and 1,590 m³ of tile drainage.