Energy at MSC: Ship lighting upgrades

The following blog is part of an ongoing series on Military Sealift Command’s Energy Conservation program (ENCON), written by the MSC ENCON team. Although it is one of the most familiar energy-saving modifications – upgrading to energy-efficient lighting – switching to more efficient technology can generate significant benefits.

After analyzing what makes economic and safety sense, MSC is replacing lights in the habitability spaces and cargo holds of ships with high-efficiency alternatives to existing fluorescent and high-pressure sodium vapor lighting.

Before LED installation; photo taken on USNS Sisler (T-AKR 311) during Cargo Hold Lighting Retrofit Measurement & Verification Testing (2,384 watts)

Before LED installation; photo taken on USNS Sisler (T-AKR 311) during Cargo Hold Lighting Retrofit Measurement & Verification Testing (2,384 watts)

After LED installation; photo taken on USNS Sisler during Cargo Hold Lighting Retrofit Measurement & Verification Testing (1,327 watts, 44% savings)

After LED installation; photo taken on USNS Sisler during Cargo Hold Lighting Retrofit Measurement & Verification Testing (1,327 watts, 44% savings)

Although prices are coming down for energy-efficient lighting, it doesn’t always save money to replace lighting as soon as possible. To determine the right time to change, we balance the energy saved – based on the operating profile – against the cost of replacing the lights. For instance, in areas where lights are not on very often, it may make more sense to wait to replace all the lighting in that area until one goes out. As part of our analysis, we have been testing various types of lighting to demonstrate what works the best and to accurately measure the energy savings from replacing current lighting with more efficient lighting. Other trade-offs are between replacing lightbulbs and installing intelligent light switches.

Two promising energy-efficient lighting alternatives are T8 fluorescent, and more recently, light-emitting diode (LED). Both T8s and LEDs use significantly less energy to produce the same luminance and have increased life expectancy over the T12 fluorescents. For an overview of these types of lights, see Fluorescent T8 vs. T12 Bulbs  and Fluorescent vs. LED Lighting .

Two ship classes that have received lighting upgrades are the T-AKR and T-AKE. Twelve T-AKR large, medium-speed, roll-on/roll-off ships have been retrofitted with T8 lighting in the habitability spaces. This new lighting will reduce the instantaneous lighting load of these fixtures by approximately 40 percent while providing similar lighting levels. This equates to an estimated fuel savings of approximately 400 barrels per year for USNS Dahl (T-AKR 312).

MSC ENCON recently supported the procurement of more than 17,000 LED lamps that will replace a portion of the T8 fluorescent lamps in the Navy’s 14 T-AKE dry cargo/ammunition ships. Currently, the lighting on board makes up four percent of the total class fuel usage, which equates to nearly $10.5M per year. Conservative cost analyses estimate a payback of the cost of procurement of the LED lamps in 2.1 years after installation.

In the original design of the vessels, the cargo hold lighting could only be shut off using circuit breakers that were not very conveniently located. The result? Lights were typically left on whether or not anyone was working in a cargo hold. The last four T-AKEs built were equipped with switches located in the vicinity of the holds, but the ENCON team oversaw another initiative to install cargo hold light switches on the other T-AKE vessels.

 

About jmarconi