In the pursuit of net-zero emissions, how clean energy is procured can make a significant difference. There are three primary approaches: Volumetric Matching, Emissions Matching, and Temporal Matching.
Volumetric Matching: Procuring enough clean energy in a year to offset annual energy usage.
Emissions Matching: Procuring an excess amount of clean energy compared to what is directly consumed. This surplus clean energy is used to offset the carbon emissions associated with any non-renewable energy used within the system. This approach is based on the idea that the increased production of clean energy can help counterbalance the use of carbon-emitting sources in the overall system.
Temporal Matching: Procuring or producing clean energy precisely when it is needed, hour by hour.
Recent research from Princeton looks into the effectiveness of each approach at reducing emissions in the US. This research supports the already growing trend toward temporal matching. While the first two practices showed minimal impact on system-wide emissions, the study concluded that "Matching a consumer’s demand hour-by-hour with new, locally-generated carbon free electricity significantly reduces system-level carbon emissions, but does so at a cost premium."
If you are thinking about entering into a long-term contract for clean energy, you might want to consider whether temporal matching will better align your investment with your sustainability goals over the term of the contract.