Public Repository for the Waste-to-Energy System Simulation (WESyS) Model
This work was supported by the U.S. Department of Energy under Contract No. DE-AC36- 08GO28308 with Alliance for Sustainable Energy, LLC, the Manager and Operator of the National Renewable Energy Laboratory. Funding was provided by the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy, Bioenergy Technologies Office. We thank representatives from several organizations, including Pacific Northwest National Laboratory, Waste Management, Inc., California Air Resources Board, Mainstream Engineering, The Water Research Foundation, HDR Inc., and Brown and Caldwell, for providing helpful comments and suggestions about the model. The views and opinions of the authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe upon privately owned rights.
The leveraging of waste streams for energy and chemical production could add revenue to waste disposal operations, and it presents opportunities for addressing a variety of economic and environmental objectives at the local, state, and national levels. The Waste-to-Energy System Simulation (WESyS) model is a system dynamics model that was created to simulate the development of the U.S. waste-to-energy industry over time. For each of the three primary waste resources modeled (landfills, concentrated animal feeding operations, and publicly owned treatment works), WESyS simulates technically feasible scenarios for the waste, including direct conversion to fuels, and anaerobic digestion followed by flaring, electricity generation, combined heat and power, cleanup and compression to compressed natural gas, and cleanup and injection into an existing pipeline. WESyS allows users to explore numerous plausible future scenarios for the development of the U.S. waste-to-energy industry. This report provides an overview of the WESyS model and documents the key assumptions, equations, and data sources used to create the model.
Please see related WESyS Documentation for a detailed summary of outputs and inputs.. WESyS is a high-level, long-term model developed to provide insights regarding the possible evolution of the waste-to-energy industry; it is not intended to be a precise forecasting tool or predictive model. It is important to recognize that insights are subject to the limitations of data inputs, model structure, scenario design, and assumed values. Accordingly, analysis with WESyS often consists of insight development, followed by careful identification of conditions under which the insight is likely to hold true. In order to gain a view into the evolution of the waste-to-energy industry, WESyS focuses on the interplay between marketplace structures, various input scenarios, and government policies. WESyS is particularly adept at addressing the following types of inquiries: · Which sources of feedstock might plausibly contribute to energy production in different regions of the United States, and how much energy potential do they have? · Under what combination of policies does the waste-to-energy industry experience gradual, sustained growth? · How do different oil price scenarios impact the build out of the waste-to-energy industry? WESyS was designed in a top-down, modular fashion which allows material (feedstocks) to flow down the supply chain and be converted into various types of energy, with feedback mechanisms among and between the various modules. Systems of equations (both algebraic and integro-differential), within the sectors and spanning sectors and modules, specify the relationships between variables such as prices, costs, facilities, resources, and material. In some cases, the equations represent physical or economic constraints or relationships, whereas others embody behavioral models such as investor decision-making and consumer choices. In general, WESyS endogenizes the determination of prices, production, investment, and demand and relies on exogenously specified scenarios for boundary conditions such as energy prices. The structure of WESyS is transparent, modular, and extensible, enabling standalone analysis of individual modules as well as testing of different module combinations, with modules for each region and feedstock combination as well as for global settings. Each module reflects decisions on facility construction and operation based on the net present value of the potential cost/benefit of investing or operating a waste-to-energy technology. The seven options available in WESyS for use of waste-to-energy technologies are categorized as two that do not use anaerobic digestion (1. no waste-to-energy; 2. biofuel produced via hydrothermal liquefaction) and five that do use anaerobic digestion or direct biogas generation in landfills (3. Flaring; 4. combined heat and power; 5. electricity generation; 6. pipeline injected renewable natural gas; 7. compressed natural gas.) For technologies that are not commercially mature, the model represents two production scales (pre-commercial, and full-scale commercial). The model is solved numerically at a sub-monthly level and typically reports output for the timeframe of 2015 to 2040. Although the description herein implies a linear flow of information between the modules, in reality, the modules receive and react to information in a complex, non-linear fashion that depends on, among other things, industrial learning, project economics, installed infrastructure, and investment dynamics. The model is geographically stratified into two regions: California (CA) and the rest of the U.S. (ROTUS).
Stella 10.3 or later. Stella is a proprietary software and is available here: https://www.iseesystems.com/