Decision-support for Digester-Algae IntegRation for Improved Environmental and Economic Sustainability (DAIRIEES)

Manure management is a major concern for dairy farms, as manure emits significant quantities of greenhouse gases and contains concentrated nutrients, especially nitrogen and phosphorus. Current manure management practices consist of spreading minimally processed manure on agricultural fields, which releases greenhouse gases directly to the atmosphere and often leads to nutrient overloading on fields and runoff to surface and groundwater. A novel manure treatment system has been proposed that mitigates many of the current environmental concerns and creates value added products from the manure including bioplastics, electricity, fertilizer, and animal bedding. DAIRIEES, an Excel based model, allows users to enter characteristics about a dairy farm's manure, manure management plan, and regional market. Based on these inputs, the five main processes of the integrated system—fermenter, anaerobic digester, bioplastics reactor, algae cultivation, and hydrothermal liquefaction or fast pyrolysis system—are analyzed in detail using data from laboratory scale experiments supplemented by information on full-scale processes from the literature. The model can be used to estimate performance of the integrated manure treatment system, including: 1) carbon and nutrient sequestration, 2) quantities and market value of end products, and 3) the system's overall economic viability. The DAIRIEES model outlines the major economic considerations for construction and operation of a full scale integrated treatment system. This information can be used to inform a more detailed pro forma analysis of the deployed system.