3. Regional NOx legislation
Besides the IMO proposal aiming at global NOx limitations, several national authorities are planning even tighter restrictions on NOx within their own boundaries. There are also regional co-operation in some areas aiming at regional restrictions (Fig. 4).
Figure 4. Strategies to comply with potential tight regional NOx legislation.
3.1 Proposed California NOx legislation
For Californian waters, two different proposals have been put forward for regulation of NOx emissions, i.e. one proposal from CARB (California Air Resource Board) and another from EPA (Environmental Protection Agency).
3.1.1 CARB proposal
CARB has proposed 600 ppm at 15% O2 as an emission standard for auxiliary engines and new ships. For existing ships, 750 ppm at 15% O2 is proposed for auxiliary engines and 600 ppm at 15% O2 for main engines. The proposed legislation is to be applied in combination with diesel oil with a maximum sulphur content of 0.05%.
The CARB proposal for new main engines (130ppm at 15% O2) is so stringent that a selective catalytic reduction (SCR) type of catalyst must be employed.
3.1.2 EPA proposal
The EPA has proposed an emission fee for voyages to the ports of Los Angeles/Long Beach:
・Base emission fee: USD 10,000/ton of NOx
・Calculation
-Baseline: NOx (g/kWh)=64.3 rpm-0.2
-Fee reduction: 90%; for ＞80% NOx reduction
: 50% for 30-80% NOx reduction
: 0% for ＜30% NOx reduction
To attain 80% NOx reduction an SCR-type catalyst should be installed. A NOx reduction of 30-80% from the baseline is achieved by utilizing the "LOW NOx Combustion" concept.
