Executive Summary

The quest for a more reliable, secure, and clean energy system is driving investment in microgrid technologies that can deliver superior reliability and resiliency than the nation’s aging and vulnerable grid.

A microgrid is a self-sufficient energy system that serves a discrete geographic footprint, such as a college campus, hospital complex, business center, or neighborhood. Within microgrids are one or more kinds of distributed energy (solar panels, wind turbines, combined heat and power, generators) that produce its power. This decentralized group of electricity sources and loads are normally connected to the traditional electric grid but can also disconnect and function autonomously.

Microgrids typically consist of a solar photovoltaic system, battery storage and a backup generator system or a backup fuel cell system that runs on hydrogen, natural gas, propane, diesel, gasoline, or other suitable fuels. The real-world analysis presented in this paper demonstrates how propane is positioned to be the fuel of choice for microgrids when natural gas is not available.

Propane, which is easily transported and stored on site for indefinite time periods, offers economic and environmental benefits that make it the best low-carbon fuel choice compared to diesel-powered microgrids. The author shows how propane is competitive to diesel for microgrid applications requiring resiliency offering diesel-like efficiencies, comparable levelized cost of electricity and lower emissions.

Two case studies in the paper illustrate the benefits of using propane generators in hybrid microgrids. The first light commercial application uses propane generators in a community housing development in San Diego, California. It compares test results from a generic diesel backup generator, an off-the-shelf propane generator, a combined heat and power (CHP) engine generator, and a propane solid oxide fuel cell. The second presents findings from a large commercial operation in Mammoth Lakes, California.


Light Commercial Microgrid (<100 kW generation system)
  • Propane is competitive to diesel for microgrid applications requiring resiliency when employing the “right” generator.
  • The lower maintenance costs and durable design of propane engines with diesel like efficiencies at this size range enable significant reductions in carbon dioxide emissions. Near zero emissions of NOx and CO can be realized with propane engines using a simple three-way catalyst.
  • Propane also opens the doors for fuel cells in hybridized microgrids.
Large Commercial Microgrid (>100 kW generation system)
  • Propane is competitive to diesel for microgrid applications requiring resiliency when employing a commercial-off-the-shelf lean-burn engine solution.
  • Propane fuel cells have a higher levelized cost of energy as compared to a diesel generator, but can enable near-zero emissions for NOx, HC, and CO.
  • Further efficiency improvements can be realized by capturing the waste heat from the generator and stored using thermal energy storage systems, then utilized for district heating or process heating to supplement the community housing’s or commercial facility’s heating needs.

To read the full study, conclusion, and recommendations, view the view report below.

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