The California Air Resources Board (ARB) will present new draft rules for ship auxiliary engines at a workshop this month, Bunkerworld has learned.

The current rules for distillate fuels were ruled illegal by a district court last year, and this decision was upheld by two appeals to a higher court, with the latest appeal rejected last month.

The original court decision rested on classifying the rules as either 'standards', which would require federal approval, or 'in use requirements' that California could implement itself.

It was the Alternative Control of Emissions (ACE) provision in the regulations that the court was most interested in, which led to the conclusion that the distillate fuel requirement was actually a 'standard'.

ARB said that it will propose an "essentially identical" regulation at its upcoming ship fuel workshop on May 13 that will "more explicitly" require the use of low-sulphur distillate fuel.

"Included in our presentation will be staffs proposal to remove the Alternative Control of Emissions (ACE) provision in the existing regulation," it said in the workshop notice.

ARB also noted that it did not think that the ACE provision was required as no shipowner had to date applied for the plan.

Also under consideration will be the planned regulations to require the use of distillate fuel in ship main engines in California ports and waters.

At its workshop in March for stakeholder consultation, ARB hinted that its proposed main engine rules would simply specify a type of fuel with methods of alternative compliance - such as scrubbers - restricted or not permitted so as to make the rules 'in use requirements'.

The legal action against the auxiliary engine rules was brought by the Pacific Merchant Shipping Association (PMSA).

At the time of the original court decision against the rules, PMSA president John McLaurin said the industry preferred federal or international standards, "which will ensure consistent application of air quality rules and meaningful emissions reductions throughout the world."

The PMSA has recommended to its members that they use distillate fuel in their auxiliary engines even in the absence of a legal requirement to do so.