How do you calculate Scope 2 emissions from a renewable PPA, and are emissions zero under both market-based and location-based methods?

If your PPA includes proper certificates and they’re retired for your use, your emissions are zero under the market-based method.

Under the location-based method, you still use the national or regional grid average, so emissions are not zero.

In short: market-based = zero (with certificates), location-based = grid factor applies.