It doesn't look like Blackmagic has published detailed power consumption specs for these products, but since these are all bus-powered devices they would need to fit within the power delivery standards of the relevant ports:
- Thunderbolt 1 or 2: up to 9.9W (550 mA @ 18V)
- USB 3.0: up to 4.5W (900 mA @ 5V)
Given that the Intensity Shuttle USB and Thunderbolt share vary similar hardware, I'd be surprised if the Thunderbolt version consumed significantly more power than the USB model (even though this is permitted by the Thunderbolt specs).
Note that since the newer Macs only have Thunderbolt 3 ports, you would need to use Thunderbolt 2 to Thunderbolt 3 adapters in order to use these older Thunderbolt devices. Assuming these adapters have some built-in electronics (which seems likely given the price of the adapters), they may consume some power on their own (in addition to the power consumption of the attached Thunderbolt device).