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As communities, utilities, and businesses seek greater energy resilience and lower emissions, microgrids have emerged as a critical component of modern power infrastructure. Microgrids, localized energy systems capable of operating independently from the centralized grid, integrate distributed energy resources such as solar photovoltaics (PV), battery energy storage, and dispatchable generation. While renewables and batteries are essential to decarbonization strategies, they cannot yet provide reliable, long-duration power on their own. Propane is the solution.
Why Microgrids Need Dispatchable Power
Solar and wind resources typically operate at capacity factors near 30%, meaning they cannot consistently meet demand. Battery storage, while rapidly advancing, remains economically viable for only four to six hours of discharge in most applications. During prolonged outages, extreme weather events, or periods of low renewable output, microgrids require an immediately dispatchable resource to maintain reliability and prevent blackouts. Traditionally, diesel generators have filled this role, but concerns over emissions, fuel logistics, and regulatory constraints are driving operators to replace diesel with propane.
The Ideal Energy for Microgrids
While hydrogen and ammonia offer carbon-free combustion, they require complex production pathways and specialized infrastructure. Diesel and gasoline provide high energy density but come with higher carbon intensity and pollutant emissions. Propane offers a balanced tradeoff between energy density, carbon-to-hydrogen ratio, and ease of liquefaction, transportation, and storage.
Unlike natural gas, propane does not rely on pipeline infrastructure and can be transported easily to remote or disaster-prone locations. It is stored as a liquid under moderate pressure, eliminating the need for cryogenic systems. From an emissions standpoint, propane has a lower carbon-to-hydrogen ratio than diesel and produces less particulate matter and soot.
Propane in Hybrid Microgrids
This research paper evaluates propane’s performance in hybrid microgrids through two modeled case studies: a light commercial application and a large commercial application. In both cases, propane-based systems are compared to conventional diesel backup generation in terms of levelized cost of electricity (LCOE) and operating characteristics.
In the light commercial case (approximately 200 kWh/day load), the microgrid consists of solar PV, battery storage, and a 25-kW backup generator. When a commercial off-the-shelf (COTS) propane generator is used, the LCOE is slightly higher than the diesel baseline due to lower fuel-to-electric conversion efficiency. However, when higher-efficiency propane combined heat and power (CHP) engines or propane-fueled solid oxide fuel cells (SOFCs) are employed, the LCOE becomes comparable to diesel. These systems offset higher upfront costs with improved efficiency, reduced fuel consumption, and lower replacement and maintenance costs.
In the large commercial case (2,500 kWh/day load), the backup generator operates at a much lower capacity factor, around 6% annually. Under these conditions, propane COTS generators are fully competitive with diesel. Slightly higher fuel costs are balanced by lower operations and maintenance expenses, resulting in essentially identical LCOEs. This finding is especially significant for resilience-focused microgrids, where generators are used infrequently but must perform reliably when needed.
Environmental Performance
Environmental performance is one of propane’s strongest advantages in microgrid applications. The research shows that propane generators can dramatically reduce pollutant emissions relative to diesel systems.
In light commercial microgrids, propane CHP systems achieve near-zero NOx and carbon monoxide (CO) emissions. Compared to diesel generators without after-treatment, propane CHP units can reduce NOx and CO emissions by orders of magnitude. Carbon dioxide (CO₂) emissions are also reduced, by approximately 14% for propane CHP systems and up to 24% for propane SOFCs, due to propane’s lower carbon content and higher conversion efficiencies.
In large commercial applications, propane generators demonstrate similar benefits. Modeled results indicate CO₂ reductions of 4% with propane engines and up to 16% with propane fuel cells compared to diesel. NOx emissions are reduced by roughly 63% at the engine-out level, with further reductions achievable through standard exhaust after-treatment. These improvements are particularly valuable in regions with strict air quality regulations or in sensitive environments where diesel emissions pose health and environmental risks.
Pathways to Decarbonization
Propane’s role in microgrids extends beyond a conventional energy solution. Renewable propane, produced as a byproduct of renewable diesel and sustainable aviation fuel pathways, can be used as a drop-in replacement without any changes to existing infrastructure or equipment. Blends of conventional and renewable propane offer an immediate pathway to further CO₂ reductions while preserving reliability.
Additionally, propane’s compatibility with advanced technologies such as fuel cells and high-efficiency CHP engines opens the door to ultra-low-emissions microgrids. Waste heat recovery, thermal energy storage, and potential carbon capture solutions become more feasible as exhaust streams grow cleaner and more concentrated in CO₂ .
Resilient and Clean Microgrids
As microgrids become an essential tool for resilience, decarbonization, and grid modernization, propane stands out as a practical and scalable dispatchable energy source. In an energy landscape defined by tradeoffs, propane offers a rare combination of affordability, flexibility, and environmental performance, making it a powerful enabler of resilient, cleaner microgrid systems.
