Gridcoin rewards can consist of 2 parts: Proof-of-Stake and Proof-of-Research.

Proof-of-Stake is generating new coins based on an interest rate of 1.5% p.a. on the staking coins. Proof-of-Research adds a payment on top of a minted block reward if a user is participating in BOINC projects that are whitelisted. The number of additional GRC is dependent on the users relative participation within the BOINC network compared to all participants eligible to generate Proof-of-Research. (https://en.wikipedia.org/wiki/Gridcoin).