carn is right. Merged mining is without additional energy expenses. It's clearly visible even on your screenshots (on the right side). So far Minergate seems legit to me. Another point that could annoy you when you start mining with them is that you need to reach some threshold in order to get your mined coins "confirmed"

this steemit user just wrote an article about that: https://steemit.com/fantomcoin/@pablol/fantomcoin-balance-always-0-000000000-minergate