M
- M (Thousand Units)
- Machine Drive (Motors)
- Made Available (Vehicle)
- Magma
- Main Heating Equipment
- Main Heating Fuel
- Mains
- Maintenance Expenses
- Maintenance of Boiler Plant (Expenses)
- Maintenance of Structures (Expenses)
- Maintenance Supervision and Engineering Expenses
- Major Electric Utility
- Major Energy Sources
- Major Fuels
- Major Interstate Pipeline Company
- Make-up Air
- Manhattan Project
- Manual Dimmer Switches
- Manufactured Gas
- Manufacturing Division
- Manufacturing Energy Consumption Survey (MECS)
- Manufacturing Establishment
- Manufacturing in the Energy Sector
- Marginal Cost
- Marine Freight
- Market Clearing Price
- Market Price Contract
- Market Price Settlement (Uranium)
- Market-based Pricing
- Marketable Coke
- Marketable Petroleum Coke (Petroleum Coke)
- Marketed Energy
- Marketed Production
- Masonry
- Masonry Stove
- Mass Burn Facility
- Master Service Agreement (MSA)
- Master-metering
- Maximum Deliverability
- Maximum Demand
- Maximum Dependable Capacity, Net (MDC, Net)
- Maximum Established Site Capacity (Reactors)
- Maximum Generator Nameplate Capacity
- Maximum Hourly Load
- Maximum Streamflow
- Mcf (Thousand Cubic Feet)
- Mean Indoor Temperature
- Mean Operating Hours
- Mean Power Output (of a Wind Turbine)
- Mean Square Feet per Building
- Measured Heated Area of Residence
- Measured Reserves
- Measured Resources, Coal
- Median
- Median Streamflow
- Median Water Condition
- Medium Pressure (MP)
- Medium-Temperature Collector
- Medium-volatile Bituminous Coal
- Megavoltamperes (MVA)
- Megawatt (MW)
- Megawatt (MW)
- Megawatt Electric (MWe)
- Megawatt Electrical (MWe)
- Megawatt-Hour (MWh)
- Megawatthour (MWh)
- Mercaptans
- Merchant Coke Plant
- Merchant Facilities
- Merchant MTBE Plants
- Merchant Oxygenate Plants
- Mercury Vapor Lamp
- Merger
- Merox
- Meta-anthracite (Highest Rank Coal)
- Metal Halide Lamp
- Metallic
- Metallurgical Coal
- Metallurgical Coal (Met Coal)
- Metered Data
- Metered Peak Demand
- Methane (CH₄)
- Methanogens
- Methanol (CH₃OH)
- Methanol Blend
- Methanotrophs
- Methyl Chloroform (Trichloroethane)
- Methyl Tertiary-Butyl Ether (MTBE)
- Methylene Chloride (CH₂Cl₂)
- Metric Conversion Factors (For Floorspace)
- Metric Ton (mt)
- Metropolitan Area
- Metropolitan Area
- Metropolitan Statistical Area (MSA)
- Microcrystalline Wax
- Microgroove Heat Exchanger Tubes
- Micrometer (Micron)
- Microwave Oven
- Mid-Atlantic Regional Air Management Association (MARAMA)
- Mid-Atlantic/Northeast Visibility Union (MANE-VU)
- Mid-size Passenger Car
- Middle Distillates
- Middlings
- Midgrade Gasoline
- Miles Per Gallon (MPG)
- Military Use of Energy
- Mill
- Mill Capital
- Mill Feed
- Milling
- Milling Capacity
- Milling of Uranium
- Million (MM)
- Million Barrels per Day (MMb/d)
- Million British Thermal Units (MMBtu)
- Million British Thermal Units (MMBtu)
- Million Cubic Feet (MMcf)
- Million Gallons per Day (MMgal/d)
- Million Metric Tons (MMmt)
- Million Short Tons (MMst)
- Minable
- Mine Capital
- Mine Count
- Mine Safety and Health Administration (MSHA)
- Mine Type
- Mineral
- Mineral Lease
- Mineral Rights
- Mineral-Matter-Free Basis
- Minimum Streamflow
- Mining
- Mining Operation
- Minivan
- Minority Carrier
- Miscellaneous Petroleum Products
- Miscellaneous Reserves
- Mixed Waste
- Mobile Home
- Moderator
- Modules
- Moist (Coal) Basis
- Moisture Content
- Mole
- Montreal Protocol
- Motor Gasoline (Finished)
- Motor Gasoline Blending
- Motor Gasoline Blending Components
- Motor Speed
- MPG Shortfall
- MSHA ID Number
- Multiple Completion Well
- Multiple Cropping
- Multiple Purpose Project
- Multiple Purpose Reservoir
- Municipal Solid Waste (MSW)
- Municipal Waste
- Municipal Waste to Energy Project or Plant
- Municipality