Overview
The environmental benefit of a megawatt-hour (MWh) of clean power is not uniform. Its impact on the environment, specifically in terms of emissions, is determined by which existing power plant it effectively replaces or pushes offline. The timing and location of clean power generation are critical factors in realizing environmental gains.
Research Context
A standard MWh provides consistent utility, irrespective of its generation source, for tasks such as charging a phone or operating a dishwasher. However, the environmental valuation of this MWh is variable. Its value concerning climate and local air quality is contingent on the specific power plant it displaces from the grid. The central premise is that a newly introduced wind turbine, for instance, contributes to climate improvement and local air quality only to the extent that it substitutes for a power plant with higher emissions. If, instead, the wind turbine's output competes with or displaces another existing clean energy source, the associated environmental benefit is effectively diminished or absent.
Findings
- The environmental value of a megawatt-hour is not constant; it is primarily determined by the type of power plant it displaces.
- A new clean energy source, such as a wind turbine, contributes to climate and local air quality improvements only when it displaces a more polluting power plant.
- When a clean energy source competes with or displaces another clean energy source, the environmental benefit is effectively nullified.