Maintenance - Set of inspections, repairs or modifications of individual wind turbines or wind farms to ensure optimal operation.

Medical waste - Also known as clinical waste, normally refers to waste produced on healthcare premises such as hospitals, clinics, doctors offices, labs and nursing homes. They are normally bio-hazardous or infectious and may contain blood, objects contaminated in medical procedures and body parts.

Membrane bioreactor (MBR) process - Multistage waste water treatment process which combines biological waste oxidation and membrane separation in order to remove effluents.

Membrane separation - Technologies utilized to remove water vapor and carbon dioxide from natural gas.

Metallurgical coal - A higher-quality coal used in making coke. Also known as coking coal.

Methane hydrocarbons - Main atmospheric pollutants released in the process of oilfield exploitation and the production of petroleum.

Methane recovery and utilization - Technology designed to capture methane released in coal mine-related emission and utilize it in various applications. Utilization includes, among other things, injecting recovered methane into natural gas pipelines.

Microalgae diesel - Diesel produced from microalgae (photosynthetic organisms) that can be farmed in water.

Micrositing - Consideration of an array of factors related to wind flow, terrain, local power demand, environmental and land-use issues carried out during site selection for wind turbines to maximize wind farm’s operational efficiency and economics.

Mixed refrigerant cycle (MRC) - Applications are used to liquefy natural gas. Considered to be an efficient and cost effective technology and used in various Chinese liquefied natural gas plants.

Modular high-temperature gas-cooled reactors (MHTGCR) - Type of nuclear reactors that are safer and have higher efficiency when compared to conventional nuclear reactors.

Monitoring and measurement solutions - Solutions that track the composition or volumes of water flows in natural water sources, water distribution systems, water treatment plants or user premises, which are often integrated with IT and or GPS technologies.

Multiple units (MU) train - Trains that rely on a series of self-propelling carriages controlled from one cabin for its propulsion, instead of locomotives.

Municipal solid waste (MSW) - Waste materials generated by urban areas, and are typically dealt with by incineration or placement in landfills. Composting and solidification are other disposal methods.