- Attainment / nonattainment area
- A regulatory classification of whether a geographic area meets federal air-quality standards for a given pollutant. Building a large emitting source in a nonattainment area triggers far more demanding permit requirements, including the most stringent control technology and possible emissions offsets, which can make a combustion project un-permittable at scale and often decides which generation technology a site can actually use.
- Behind the fence / behind the meter
- Power generation sited on the data center's own land, inside its fence line and on the customer's side of the utility revenue meter, so the electricity is produced and consumed on-site without transacting across the grid. In practice both phrases describe the same self-supply strategy that lets an operator avoid waiting in the interconnection queue for its primary power.
- Carbon capture and sequestration
- Capturing carbon dioxide produced by combustion before it reaches the atmosphere and storing it underground in geological formations. It is the oil-and-gas majors' proposed method for managing the emissions of gas-fired data-center power, but it is energy-intensive, often under-delivers on capture rates, and depends on policy support, so capture-equipped gas power is best regarded as lower-carbon rather than zero-carbon.
- Combined-cycle gas turbine
- A gas turbine plant in which the turbine's hot exhaust drives a heat-recovery steam generator and a second steam turbine, capturing energy that a simple-cycle machine wastes. It offers the highest fuel efficiency and lowest carbon intensity per megawatt-hour among the combustion options, at the cost of longer lead times and, currently, constrained turbine supply.
- Firm capacity
- The guaranteed ability to deliver a given number of megawatts at any moment, including peak demand and adverse conditions, as distinct from total energy delivered over time. AI data centers require firm, around-the-clock capacity, which favors dispatchable sources like gas engines, turbines, and fuel cells over intermittent renewables.
- Interconnection queue
- The process by which a new generator or large load requests permission to connect to the shared grid, including the studies of how the connection affects the surrounding network. In many U.S. regions these queues have grown so long that the study process alone runs several years, making the grid unable to serve fast-moving AI compute demand on time.
- Reciprocating gas engine
- A large piston engine running on natural gas to drive a generator, deployed as modular units arrayed in parallel. Prized for fast, phased deployment and strong load-following, but it emits more NOx at the source than turbines or fuel cells and typically relies on after-treatment such as selective catalytic reduction to meet emissions limits.
- Solid-oxide fuel cell
- A device that converts the chemical energy of natural gas, hydrogen, or biogas directly into electricity through an electrochemical reaction across a ceramic electrolyte, without combustion. Because it has no flame front, it emits very little NOx and other criteria pollutants, making it far easier to permit in strict air districts, though it carries a higher capital cost per megawatt. Bloom Energy's Energy Server is the reference product.