Well, I won’t keep you in suspense, the results are as follows (from the most to the least environmentally friendly).
Credit transfers and debit transfers in batch mode. Credit transfers are better for the environment than debit transfers. In fact credit transfers are better than debit transfters all round which is why we should all be buulding “single credit message” (SCM) infrastuctures and layering request-to-pay (R2P) and variable recurring payment (VRP) layers on top for the use of businesses and customers. Not only the most environmentally friendly but also the overall lowest cost platform for the wider econony