Renewable Energy Certificates (RECs) are tradable, contractual instruments that represent the full suite of attributes of 1 Megawatt-hour of renewable energy generation on the electricity grid. Essentially, a REC represents the environmental benefits of 1 megawatt-hour of renewable electricity that can be paired with electricity. RECs are the sole means to claim usage of grid-connected renewable electricity in the United States, and may be used as the compliance instrument for consumption- or delivery-based state Renewable Portfolio Standards. Renewable electricity generation and use are tracked through RECs, and so by matching RECs with your electricity service you are using renewable electricity.
Video Credit: Center for Resource Solutions
Understanding Carbon Offsets
Carbon Offsets represent the reduction of a specific quantity of greenhouse gas (GHG) emissions. By purchasing these offsets, the customer has the right to all associated claims about the environmental benefits they embody. Carbon Offsets are a real environmental commodity, not a donation or investment in a future emissions reduction project. The verified GHG emissions reductions purchased are sourced from projects that have been validated and registered under high-quality project standards. (page 23: https://www.green-e.org/docs/climate/CodeofConduct.pdf)