Ocean Currents

Improving the Safety of At-Sea Fuel Transfer

Reducing the risk of oil spills in Western and Arctic Alaska

Loading anchored oil supertanker via a ship-to-ship oil transfer
Refuelling or bunkering in marine terms is carried out using a small raid tanker to pump the bunker fuel into the bigger ship via a ship-to-ship oil transfer (STS). © Igor Groshev

Alaska’s remote coastal communities aren’t on the road system, so when they need fuel—like diesel, home heating fuel, gasoline or jet fuel—it is delivered by ship. The coastal waters in western and Arctic Alaska are shallow and deep-draft boats can’t deliver fuel to shore. Instead, fuel is transferred—on the ocean—from large, deep-draft ships to smaller vessels. This process is known as “lightering” or “ship-to-ship transfer.”

“Lightering…is the process of transferring petroleum cargo from one vessel to another.”

While fuel delivery is vital to remote communities, the process of at-sea transfer presents an obvious risk: the oil could spill and contaminate the water. In the Arctic, a major marine oil spill could have disastrous consequences for the region’s abundant birds, fish and marine mammals. It could also have severe impacts on indigenous residents who rely on those animals as important sources of food and as a cornerstone of traditional cultural practices.

There is So Much at Stake

Ocean Conservancy commissioned consultants at Nuka Research and Planning, LLC, to research and write a report that described how the process works, how it is regulated, what risks are involved and how those risks might be minimized.

The report revealed that at-sea transfer of fuel in western and Arctic Alaska has changed in recent years. In the past, barges delivered the most fuel in the region. But starting around 2012, companies began to rely on larger oil tankers capable of carrying higher volumes of fuel. These tankers may spend weeks or months at a time off the coast of Alaska, transferring their cargo onto barges for delivery to towns and villages. While the overall amount of fuel delivered hasn’t increased, larger volumes are located in one place.

“Potential environmental impacts associated with lightering operations . . . may include oil spills resulting from the transfer operation, a grounding, or collision involving the tanker, tug, or barge.”

At-sea transfer of fuel is subject to federal regulations and international norms. When the transfers happen in Alaskan waters—generally within three nautical miles of shore—they are subject to the state’s spill prevention and response planning requirements. At times, vessels engaged in fuel transfers may be required to have a state-licensed marine pilot on board. In addition, operators who carry out fuel transfers apply their own safety standards, expertise and experience. So far, this system has worked well: there have been no recorded spills from ship-to-ship transfers of fuel in the region.

Close Calls

But there have been close calls. In 2016, a nearly 600-foot Norwegian-flagged tanker ran aground near Nunivak Island with 24 people and 11.5 million gallons of petroleum products on board. Fortunately, the ship’s crew was able to refloat the vessel and move it to deeper water, and the accident caused no injuries or spill. Outside of Alaska, a tanker refueling operation went awry in San Francisco Bay in 2009 and spilled 400 gallons of fuel into the water.

Improving Safety

The companies that conduct at-sea fuel transfers in western and Arctic Alaska have excellent safety records. At the same time, Nuka’s report identified mitigation measures that could strengthen the system. Some of the recommendations include:

  • Considering remote monitoring of at-sea transfer operations using onboard cameras to facilitate oversight and enforcement.
  • Continuing to update nautical charting in the region, with a priority on charts in areas that are used for at-sea transfers. Alternatively, in some cases, operators could consider conducting at-sea fuel transfers in areas already been charted to modern standards.
  • Identifying preferred locations for ship-to-ship transfers, or areas where these transfers should not take place. This should be done in conjunction with local waterway users, including subsistence hunters and fishermen and commercial fishermen.
  • Identifying best practices with respect to the weather and sea conditions under which ship-to-ship transfer operations should or should not take place.
  • Considering pre-placement of boom before fuel-transfer operations take place so that containment equipment is in place in the event of a spill.
  • Considering enhancements to spill response equipment carried on barges so that it is better suited to respond to an oil spill in rough offshore environments.
  • Conducting drills, exercises and planning exercises to promote a rapid and effective response to oil spills and test preparedness for a major event, such as a tanker grounding in remote waters.

Looking Toward the Future

At-sea transfers make it possible to deliver fuel that is critical to remote communities in this region. To date, these fuel transfer operations have not had any reported spills, and the companies involved deserve credit for their good work.

“While there have been no recorded spills from [Alaska lightering] operations to date, there may still be opportunities for operators and communities to explore risk mitigation measure that may be achievable without adding undue costs to . . . fuel deliveries.”

At the same time, there are significant risks from the transfer of fuel at sea. Nuka’s report suggests opportunities for additional mitigation measures to further protect against oil spills that could harm wildlife and habitat, or adversely affect subsistence users or commercial fishing operations. We look forward to discussing these measures with other waterway users and exploring the potential to implement even stronger best practices or standards of care for Alaska’s remote waters.

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