Following the worldwide and European commitments to tackle climate change, also the Oil&Gas sector is significantly acting to limit GHG emissions.
RINA is supporting O&G contractors to define/implement GHG emissions reduction strategies; specifically, since 2018 support has been provided to SAIPEM with specialist services in the field of energy/GHG assessments: as of June 2021, 24 assets were analysed, of which 8 offshore (4 pipelaying and 2 drilling ships, two semi-submersible, one jack-up drilling unit). Based on the outcomes of these analyses, good practices booklets per asset type were also redacted, aimed at promoting GHG emissions reduction and increasing the Company competitivity.
The typically identified actions concern the optimization of power generation, thrusters, hull, consumptions monitoring, electric motors, etc. The set of actions typically allow - if implemented - a reduction of GHG emissions of 10-25%, with payback of the investment below 3 years.
This paper specifically focuses on two actions, i.e. optimization of steam system/freshwater production and the control of cooling pumps through VFD.
Indeed, steam systems onboard vessels became largely oversized following the phase-out of HFO as fuel, with steam used only for freshwater generation plus minor uses; installing a two-stage reverse osmosis system strongly reduces GHG emissions and freshwater production costs.
As for generators and thrusters cooling, it is generally based on double freshwater/seawater circuits; in both, pumps are not VFD-controlled, thus working at constant power and flow rate even at low cooling load. Installing such a control system allows significant electricity and fuel savings, thus avoiding a considerable amount of GHG emissions.
Following the growing recognition of climate change risks, 195 governments signed in December 2015 the Paris Agreement [1], committing to tackle climate change and limit to well below 2°C the increase of global average temperature, pursuing efforts to limit it to 1.5°C above pre-industrial levels.
In this context, the proposed European Climate Law [2] foresees a GHG emissions reduction target of at least 55% by 2030 as a steppingstone to the 2050 climate-neutrality goal. The legislative proposals that during 2021 will implement this target include:
