Grass Biomass vs. Coal and Natural Gas: A Comparative Energy and Cost Analysis for Distributed Power Systems
Executive Summary:
This white paper evaluates grass biomass, coal, and natural gas across energy yield, economic cost, carbon footprint, and infrastructural scalability, particularly for decentralized and small-scale energy systems.
Despite coal and natural gas's higher raw energy density, we find that grass biomass can deliver competitive and even superior cost-effectiveness per megawatt-hour (MWh)—especially when grown and processed locally. Moreover, it offers substantial climate and ecological advantages.
Energy Yield ComparisonCoal (Bituminous):Energy content: ~24–26 million BTU/ton Electrical conversion efficiency: ~33–38% (large-scale) Usable electricity: ~2.4–2.9 MWh/ton Natural Gas (Pipeline quality):Energy content: ~1,030 BTU/ft³ ~1,000 ft³ = ~1 MMBTU Conversion efficiency (modern turbines): 40–60% Usable electricity: ~0.11–0.17 MWh per 1,000 ft³ Grass Biomass (e.g., Switchgrass, Miscanthus):Dry biomass energy content: ~15–18 million BTU/ton Small-scale conversion efficiency: ~20–30% (combustion or gasification) Usable electricity: ~1.1–1.3 MWh/ton
Fuel Cost and Energy Cost ComparisonMetricGrass Biomass (Dry)Coal (Bituminous)Natural Gas (U.S. Henry Hub)Energy per unit (usable)~1.2 MWh/ton~2.5 MWh/ton~0.13 MWh/1,000 ft³Cost per unit$30–80/ton$40–120/ton$2.00–4.50 per 1,000 ft³Cost per MWh (fuel)$25–67$17–50$15–35Note: Natural gas prices are volatile and location-dependent. Figures above reflect 2023 U.S. domestic average.
Environmental ImpactCategoryGrass BiomassCoalNatural GasCarbon Footprint~0 net (biogenic CO2)~2.86 tons CO2 per ton~117 lbs CO2 per MMBTU (~0.06 tons/MWh)Methane LeakageNoneNoneYes (fugitive methane ~1–3%)Sulfur/Heavy MetalsMinimalHighMinimalAsh ContentHigh silica ash (non-toxic)Toxic fly ashNoneAir PollutionMinimal with proper combustionMajor SOx/NOx/PM emissionsNOx and CH₄ leaksRegenerative UseBiochar return, soil improvementNoneNoneGrass biomass can be carbon-negative when pyrolyzed to biochar and sequestered.
Infrastructure & ScalabilityFactorGrass BiomassCoalNatural GasInfrastructure CostLow (boiler/gasifier scale-flexible)High (mines, rail, scrubbers)Medium (pipelines, turbines)Land ImpactPositive (restorative)Negative (destructive mining)Moderate (pipeline right-of-way)DecentralizationHigh (small/local systems)Low (centralized plants)ModerateTransport & LogisticsMinimal (on-site)Intensive (rail, barge)Complex (compressed/gaseous delivery)5. Economic Implications for Microgrids and HOAsGrass: Ideal for regenerative community systems Natural gas: Cost-effective for peak loads but dependent on volatile supply Coal: Obsolete for distributed systems due to pollution and logistics
ConclusionWhile natural gas offers strong fuel efficiency and lower CO₂ than coal, grass biomass remains competitive on a per-dollar basis and excels in carbon circularity, local generation, and ecosystem services. When leveraged at the community level, grass biomass systems outperform both fossil fuels in resilience, sustainability, and autonomy.
ReferencesU.S. Department of Energy, Biomass Energy Data Book EIA, Average Energy Consumption per Household EPA GHG Equivalency Calculator Demirbas, A. (2007). Combustion systems for biomass fuel. Jenkins, B. et al. (1998). Combustion properties of biomass License: This white paper is offered under Creative Commons Zero (CC0) and may be freely copied, modified, and distributed.
