Renewable energy certificates (RECs) represent the property rights to the environmental, social and other non-power attributes of renewable electricity generation. They are either kept by the renewable electricity generator (i.e. wind farm) or they become a part of the generators' revenue and sold on the market. One megawatt-hour (MWh) represents one REC.
When you purchase RECs (or when we purchase them on your behalf), you are taking ownership of wind energy that's being fed onto the grid. Once energy reaches the grid, it mixes together with the energy from coal and hydroelectric plants, solar farms, landfill gas, etc.
Utility companies then pull indistinguishable electrons off the grid and deliver them to homes and businesses. It is impossible to determine where the electrons came from - all consumers can do is ensure that wind energy is being matched through the purchase of RECs.
Wind farms rely on the revenue from RECs to offer their energy at a price that is competitive against fossil fuels. Anybody who says they're using renewable energy - even big companies like Google - are purchasing both physical electrons from the grid and RECs.
By purchasing RECs, you're increasing the demand for clean energy - which expands access and availability, helps the environment, and reduces our reliance on fossil fuels - without having to install and maintain your own equipment.