Local integrator and mtu Onsite Energy deliver power generation to remote Alaskan sites
Posted on June 26, 2012
Marsh Creek, LLC designs, builds and equips power plants for rural communities and oilfield operations in Alaska’s harsh environment.
Marsh Creek has shown that it’s very comfortable in both Alaska’s brutal cold and its farflung power customer sites. For years, the company has been providing power-generating equipment housed in modular building-type power plants. These self-contained power plants serve as power sources both in remote areas throughout the state and offshore. Many of these custom power plants feature generator sets from mtu Onsite Energy, which provide reliable primary and backup power for some of the state’s smallest communities and largest energy operations. Marsh Creek is the only firm in Alaska with the load bank capacity — 18 MW medium voltage — needed for testing and diagnostics mandated by code and industry requirements to support power plant development.
Modular power plants for off-grid communities
In Alaska, hundreds of remote rural villages like Nikolai are off the power grid. These communities get their electricity from stand-alone diesel-powered power plants. In recent years, many old and inefficient power plants throughout the state have been replaced with modern, efficient units thanks to a program run by the Alaska Energy Authority (AEA). Once a new modular power plant is installed, fuel consumption often decreases 30 percent, resulting in fuel savings ranging from roughly 5,000 gallons per year at the smaller installations to around 25,000 gallons per year at the larger ones.
The AEA program has provided approximately 50 new power plants with many generator sets from Marsh Creek. These power plants are modular steel buildings that house from two to four generator sets for redundancy purposes. Also included are the controls for each generator set, all the necessary switchgear and power distribution equipment, internal fuel storage system and a computer console to monitor the plant’s operation.
Marsh Creek designs and builds complete custom power plants at its Anchorage facility and then ships them by truck, plane or barge to their destination. There, company personnel will handle tasks ranging from start-up and commissioning to the entire installation.
In addition to supplying complete new power plants, Marsh Creek replaces aging generator sets in existing power plants with new ones. As a UL-listed shop, Marsh Creek is able to modify factory-supplied generator sets as necessary for the application, ship them to their destination, and then assist with the installation or complete the whole job. The firm also repairs the generator sets when necessary and provides maintenance training to people located on-site.
Prime power generator sets meet special demands
Manufactured in large part by mtu Onsite Energy, the prime power generator sets used by Marsh Creek range in output from 50 kW to 2,500 kW. These units are typically 80 degrees Celsius temperature-rise-machines and meet the U.S. Environmental Protection Agency’s Tier 3 emission requirements.
Other key application demands met by the generators from mtu Onsite Energy include:
- Fuel efficiency. The fuel efficiency of a generator set is the number-one cost consideration when providing prime power generators for remote areas, where fuel prices can be extremely high. Unlike in a standby power application, fuel is the largest expense of any prime power operation. A power plant operating 24/7 with a 300 kW load and 14 kWh/gal efficiency can consume over 187,000 gallons of fuel in a year. At $4.00/gal delivered that’s $748,000 a year in just fuel.
- Oversized alternators. When an alternator is running, it generates heat. This heat is lost energy being radiated to the atmosphere. The more heat given off, the lower the alternator efficiency, which results in lower fuel efficiency. Oversized alternators have more copper in the windings so they run cooler and give off less waste heat, which results in better fuel efficiency. An oversized alternator that runs cooler will also last longer, and because of the larger windings, will handle large loads coming online with a lower voltage dip.
- Wet-sleeve cylinders. These provide better cooling and more even temperature distribution, which lengthen engine life. Wet-sleeve cylinders are a general requirement for prime power applications which, Wakefield notes, rules out a number of generator set manufacturers.
- Open architecture. Some manufacturers include switchgear as a part of their generator set package and, in most instances, they provide only a proprietary architecture that is sometimes referred to as “closed.” Closed systems make service and maintenance difficult, so the open architecture of mtu Onsite Energy systems’ controllers gives Marsh Creek a competitive edge.
- Turnkey products. For some prime power applications, a turnkey generator set is available directly from mtu Onsite Energy, which costs less because it doesn’t require any customizing work by Marsh Creek.
How successful has Marsh Creek’s long-running power plant project been? One measure is the relatively small number of complaints the company has received over the years. “Once the products are installed, you rarely hear about them, which is a good thing,” Wakefield said.
Critical pipeline gets black start power
Besides powering rural communities, Marsh Creek’s modular buildings are playing a number of key roles in Alaska’s thriving energy industry. For example, two 800 kW black start modules are now available for duty along the Alyeska Pipeline, which transports crude oil 800 miles from Prudhoe Bay, the main oilfield in the northern part of the state, to Valdez, the major marine terminal in south central Alaska’s Prince William Sound.
Along the pipeline are a number of pump stations that keep the crude oil flowing to its destination. For the pumping equipment, primary utility power is provided by turbines. The mtu powered Black Start Arctic Modules have been permanently located at pump stations 3 and 4. Each module contains an 800 kW Prime Power mtu Onsite Energy 16V 2000 generator set. Built to last 20 years, these 16-cylinder units are “very robust” compared to competitive products, according to Wakefield.
Also included in the modules are Marsh Creek’s arctic air recirculation system, switchgear, high-resistance neutral ground fault detection, HVAC, internal fuel system and infrared fire detection system. In the unlikely event of a total power failure at the pump station, these modules will provide the last line of defense. They will provide the power required to start up the turbines and put the pump station back online. The black start modules can be operated either locally or remotely from Alyeska’s Operations Control Center in Anchorage with full monitoring and control of the generator sets, switchgear, PLC and HVAC.
According to Wakefield, proprietary features can make competitive control products difficult to integrate into an existing system or black start modules. These features can also make troubleshooting more difficult if something goes wrong. By contrast, the mtu Onsite Energy control equipment “is pretty easy stuff to work on,” he said. In addition, he noted that the architecture of the control panels makes them easier to use than competitive offerings.
Mobile units roam the oil patch
Occasionally the turbines at the pump stations must be shut down for maintenance work. When the turbines are down, reliable backup power is critical. This power can now be supplied by a pair of custom trailerized modular power plants recently constructed by Marsh Creek.
Self-contained with 800 kW generator sets and paralleling switchgear, these trailerized units move up and down the pipeline to provide power wherever and whenever it’s needed.
In some cases, a pump station shutdown might last for a day or two. During that time, Wakefield noted, the generator sets in the Marsh Creek trailer will be running constantly, making the job much more demanding than typical standby duty. In other cases, a site may have two primary turbine units. “If they swap one out, they’ll want a generator standing by as the redundant power source,” he explained.
Sometimes the trailers may be asked to play more than a backup role. For example, generator set power can be used to operate remote gate valves (RGVs), shutoff valves that can stop the flow of oil at various points along the pipeline. If workers were replacing a section of pipe, they could temporarily close the nearest upstream RGV using power from a Marsh Creek trailer. The units can also be called on to provide power for first responders in the event of a spill or some other emergency along the pipeline.
The generators also offer high reliability, which is crucial for applications in remote locations. “It costs a lot to go out to these sites, so you want a product that doesn’t require frequent adjustments or maintenance,” Wakefield said. “You might save money on the front end by choosing a cheaper product, but you’ll lose that money on the back end performing maintenance and repairs.”
Power for offshore drilling
In the last year, Marsh Creek has constructed three modular power plants for Houstonbased Eni Petroleum Co., a newcomer to Alaska’s oilfields. Eni is a subsidiary of Italy’s Eni S.p.A. Two of the modules are 2 MW power plants, each containing an mtu Onsite Energy 16V 4000 generator set with a remote radiator. The third module is a 1 MW power plant with a single 16V 2000 and a unit- mounted radiator.
Eni’s modular power plants are located offshore on a man-made island in the Arctic Ocean. There they serve as backups for the main turbines that power Eni’s drilling operation, which drills 10,000 feet below the surface in search of oil. In addition to their backup role, the power plants can be utilized to provide primary power before the turbines are up and running at new drilling sites.
Marsh Creek had to produce the second 2 MW modular power plant in six weeks to meet Eni’s schedule requirements. “We had a hard deadline without even a week of wiggle room,” Wakefield said. “They told us if we couldn’t meet that deadline, they needed to know because that would disqualify us.”
Eni needed to receive its module before the deadline so it could be transported to its manmade island, Spy Island, via an ice road. The man-made ice road is constructed after freezeup and connects Spy Island with the Alaskan coast. If the power plant wasn’t delivered before the ice road melted, Eni would have had to turn to more problematic and expensive transportation options involving oceangoing vessels.
Marsh Creek made its deadline, thanks in part to cooperation from mtu Onsite Energy. “I’ll give kudos to mtu because they shipped our equipment in much less time than normal,” Wakefield said. “In a make-or-break situation, they really stepped up.” In the end, Marsh Creek was able to deliver the power plant to Eni ahead of schedule.
According to Wakefield, Eni personnel were elated with Marsh Creek and the generator sets from mtu Onsite Energy. “To my knowledge, we’ve had zero complaints from them.” In fact, “They’ve spoken very highly of what we’ve done.”