## 2 Technological and Policy Solutions
### Policymaking Arenas  
#### 2.2.1 Imo  
The relevant IMO agreements that are currently in effect are the Energy Efficiency Design Index (EEDI) adopted in 2011 and the related Ship Energy Efficiency Management Plan (SEEMP) and the Energy Efficiency Operational Indicator (EEOI), and sulfur fuel content limitations, which were initially adopted in 2005 and then lowered in January 2020. \begin{table}
\begin{tabular}{c} \hline
**Energy Efficiency** \\ \hline Hull form \\ Efficient propellers \\ Lightweight construction \\ Reduce ballast \\ Ducktail waterline extensions \\ \hline
**Propulsion Systems and Fuels** \\ \hline Wind \\ Solar \\ Towing kite \\ Hydrogen fuel cells \\ CRP Propulsion \\ Liquified natural gas fuel \\ Distillate fuel \\ Biodiesel fuel \\ Methanol fuel \\ Battery electric \\ \hline
**Machinery Systems** \\ \hline Harbor-side auxiliary electricity (shore power) \\ Power storage \\ Waste heat recovery \\ Main engine tuning \\ Exhaust gas recirculation (with scrubbers) \\ Diesel particulate filters (DPF, various types) \\ Electrostatic precipitators (ESP) \\ Scrubbers (SOx, with exhaust gas cleaning systems) \\ Selective catalytic reduction \\ Hybrid electric storage \\ Engine tuning with selective catalytic reduction/exhaust gas recirculation \\ Diesel oxidation catalyst (DOC) \\ \hline
**Information Technologies** \\ \hline Artificial intelligence: machine learning \\ Big data \\ Engine control technologies \\ \hline
**Operational Measures** \\ \hline Propeller brushing \\ Hull brushing \\ Weather routing \\ Slow steaming \\ \hline \end{tabular}
\end{table} 
Table 7: Illustrative Technologies and Operations that Have Been Proposed by Various Sources for Reducing Shipping’s Emissions. The EEDI [66] and its related agreements are intended to improve energy efficiency and thereby reduce carbon dioxide emissions. The agreements are complex, include many technical requirements for calculations and verifications, distinguish among 13 types of ships, and differentiate the applicability of the specific requirements for individual ships according to weight, engine type, and time-of-construction. The EEDI implementation period is divided into four phases with phase 0 beginning in 2013 and phase 4 beginning in 2025, with each phase being defined in terms of varying combinations of the dates of contract-signing, keel-laying and delivery. To the extent that they make the world's international maritime shipping fleet of about 70,000 vessels more fuel efficient, they also reduce black carbon emissions, though only indirectly and without specific monitoring of those indirect effects. New sulphur regulations that entered into effect in January 2020 [67] have been a preoccupation of maritime industry participants and observers for several years. The new limit is that the sulphur content of fuel may not exceed 0.05%. However, ships with exhaust gas cleaning systems, i.e.,'scrubbers', can still use high-sulphur fuel oil (HSFO). Some types of scrubbers, i.e., those with 'open-loop systems' that could discharge water into port areas, are banned by some ports. Another issue about the reduction of sulphur emissions was noted above in the discussion of the chemical composition of shipping's emissions, namely that sulphur oxide emissions are global _coolants_. This unintended consequence of the IMO emission regulation has not been a central concern at the IMO, but there is increasing awareness of the issue. There are also two emission regulatory policymaking tracks in progress at the IMO: the Initial Greenhouse Gas Strategy and the black carbon emission control track. In April 2018, IMO members adopted an Initial Greenhouse Strategy with a 2050 target of reducing maritime shipping's total GHG emissions by at least 50% compared to 2008 [68; 69; 70]. It also includes energy intensity targets of a 40% reduction by 2030 and 70% by 2050, compared with 2008. The targets represent significant reductions from business as usual projections, and there are other targets of an aspirational nature.