Subsea all-electric has been discussed for at least 25 years, but has not yet been implemented to an industrial scale for well barrier elements. With the introduction of subsea compression stations, the default control and actuation principle is all-electric. However, for the simpler control system used for well barrier elements, the default selection is still electro-hydraulic where the actuation is provided by hydraulic power and the fail-safe close mechanism is obtained through energized springs.

The introduction of all-electric systems challenges traditional thinking with respect to safety functions as well as day to day operation. Before going all-electric, equal or improved safety level, cost and uptime must be demonstrated. Benefits with all-electric control and actuation systems are less limitations for the step out distance, as well as being more robust for deep and ultra-deep waters.

The current studies done by the industry reveal that the regulations are not necessarily well suited for this technology. This has also lead to a new NFR founded project (Safety 4.0) being launched with contribution from PSA, NTNU, UiS, DNV GL and several industrial partners. The outcome of this study is to provide new guidelines including requirements acceptable to the authorities.

The presentation will compare all-electric to traditional electro-hydraulic design, discuss how all-electric challenges traditional safety principles, how the safety and operability of the (battery powered) system can be ensured (not least through improved monitoring features) and how to compare and evaluate prediction models of all-electric with existing field data for traditional design.