Novel Floating Power Plants on the Horizon

For decades, floating power plants have been used widely as a source of flexible, decentralized power generation for several reasons. Among them are that they can be built cost-effectively and rapidly; they are mobile, which means they can be relocated or traded; and because they do not require a large site and sometimes have no land footprint, they can be deployed even in the most remote locations and under challenging ambient conditions, both for temporary or permanent power.

Some experts suggest that more than 75 floating power plants are installed worldwide. But historically, floating power plant (or vessel-mounted power plant) fleets have relied on diesel, gas, or dual-fuel engines that can run various types of liquid and gaseous fuels. For example, of the more than 20 floating power barges that Finnish power plant equipment provider Wirtsili has launched since the late 1990s in places like Bangladesh, Jamaica, and Papua New Guinea, most are fueled by heavy fuel oil.

Owing to demand for low-cost flexibility, floating power plants are seeing a resurgence. But developments on the horizon suggest the future fleet could be far more diverse and include nuclear plants, combined cycle gas turbines, and liquefied natural gas (LNG) facilities.

Floating Nuclear. On November 5, the first of two 35-MW KLT-40S reactor units aboard Russia's Academik Lomonosov reportedly sustained chain reactions for the first time. According to Russian state-owned nuclear company, Rosatom, comprehensive testing of the reactor will begin in a few days. The plant's second reactor will also be started soon.

Construction of the floating plant, which began in 2009 at the Baltic shipyard in St. Petersburg, wrapped up this April, and it was towed without nuclear fuel 4,000 kilometers (through four seas-the Baltic, Northern, Norwegian, and Barents) to Murmansk, where it arrived in May. Fuel loading began in July and wrapped up on October 2. After testing is concluded, it will be towed to its permanent base at Pevek in Russia's Far East region of Chukotka in the summer of 2019. At Pevek, it will replace the 48-MW Bilibino nuclear power plant and 35-MW Chaunskaya thermal power plant, projects Rosatom said are "technologically outdated," and it will become the most northerly nuclear power plant in the world (Figure 1).

1. A mobile nuclear plant. The Akademik Lomonosov, which could begin providing power to Russia's remote Chukotka region next summer, is one of the world's first floating nuclear plants. The two-reactor plant is 144 meters long and 30 meters wide. This image shows the barge leaving the shipyard in April 2018. Courtesy: Rosatom

Rosatom noted the plant is the main project in a series of mobile transportable power units of low power. China, meanwhile, is also developing an offshore nuclear power station, and suggested the first plant of its fleet-which is expected to include floating and submarine designs-could be delivered by 2020. Details of the fleet aren't fully known, but experts suggest at least two designs are under development, both of which are small pressurized water reactors. The Nuclear Power Institute of China, a subsidiary of the China National Nuclear Corp. (CNNC), has signed an agreement with UK-based Lloyd Register to support development of a barge that could use CNNC's ACP1000S, while China General Nuclear Power Group in 2016 started development of its ACPR50S floating plant. CNNC has also reportedly set up a joint venture that would have one billion yuan in registered capital to develop and produce small, floating nuclear power plants. Experts, however, noted multiple technological difficulties must be overcome, such as licensing, safety, radiation protection, and waste disposal.

Floating Gas Turbines. While gas turbines installed on ships and oil platforms aren't new, their power output has been limited owing to space and fuel availability constraints. Siemens hopes to change that. Following the devastating tsunami in Japan in 2011, the company's SeaFloat team has been actively developing and marketing floating platforms and ships that can be equipped with varying gas turbine models. The concept, which it offers for lease or purchase, seeks to meet what it says is surging demand from energy providers in developing nations or companies looking for flexibility in industrialized countries. SeaFloat's first order for a floating platform will be equipped with two SGT-800 gas turbines, and it could be placed by the end of 2018 and commissioned as early as the beginning of 2020, it said. However, Siemens also offers floating plants equipped with the smaller quick-start SGT-A65 aeroderivative gas turbine. "Even the large Siemens SGT-8000 H-class gas turbines will be made seaworthy in the future," the company said, noting that for combined cycle gas turbine (CCGT) power plants, outputs of up to 1.3 GW "are possible" (Figure 2).

2. Floating a heavy-duty gas plant.Siemens' SCC5-8000H SeaFloat power plant, pictured in this artistic rendering, has an SGT-8000H gas turbine on board. It could deliver up to 1.3 GW with a plant efficiency of more than 61% in a two-unit combined cycle configuration. Courtesy: Siemens

This August, the company said its SeaFloat team has developed the heavy-duty concept "to the point of readiness for series production." Because a CCGT on board a barge at sea exposes turbines to increased stress due to the swell, engineers took a "wide variety of measures to adapt supports, bearings, and other components that would dampen these wave-induced movements," it said. Engineers also considered standards that can vary from country to country and harbor to harbor.

"Once a power plant is docked, the simplest option is to supply it with natural gas from land. If the facility is located further offshore, it can also be supplied with [LNG] from ships. To make this possible, additional platforms have to be set up where ships can dock. These platforms would be equipped with the technology that is needed to convert the liquid fuel into a gaseous one," Siemens said.

Floating LNG Power Plants. While several prototypes for floating LNG power plants have been launched over the years, no commercial floating LNG-powered plants have yet set sail. However, recent advances in floating storage and regasification technologies are now making floating LNG power plants more operationally viable.

Notably, Malaysia's state-owned oil and gas firm Petronas in April 2017 launched a new era in gas production when it began operating the world's first floating liquefied natural gas (FLNG) platform-a facility that floats above an offshore natural gas field and produces, liquefies, stores, and transfers LNG to a carrier ship. Keppel's Hilli Episeyo in March 2018 became the second FLNG vessel to begin production, and Shell is nearing completion of its massive and much-watched Prelude FLNG facility offshore in Western Australia. Experts say the developments promise to broaden fuel availability and catalyze the movement toward gas-to-power projects at remote sites.

But they also note these FLNG breakthroughs are accompanied by the operational start of more floating storage and regasification units (FSRUs). Since 2005, when the first FSRU began operation in the U.S., at least 28 are now operational-three came online in 2017, and five were scheduled for delivery in 2018. In step with that trend, various power plant equipment makers have unveiled innovative designs for FLNG power vessels. As Mitsubishi Heavy Industries noted, key reasons for resurgent interest in FLNG power generation is the marked increase in global gas supply, a surge in environmental consciousness, the drive for flexibility, and most importantly, lower costs. LNG "power ships," it noted, can cut utility charges by a third compared to diesel.

Projects awarded an approval in principle (AIP) over the past year by the American Bureau of Shipping include the 100-MW Hudong-Zhonghua Shipbuilding's LNG Power Supply Vessel, which integrates an LNG receiver, storage, and regasification. The ship features GE's modular Combined Gas Turbine, Electric and Steam power trains. Last year, Japan's Chiyoda also got the marine classification society's AIP for its concept, which is based on existing LNG carriers and range from 72 MW to 400 MW, and Houston-based Power Barge Corp. won an AIP for its modular, medium-speed engine 80-MW to 180-MW power barge design. Meanwhile, approvals may be forthcoming for a project jointly developed by Lloyd's Register and Hyundai Heavy Industries for a 221-MW barge-mounted power plant running 13 HiMSEN dual-fuel engines. Samsung in 2017 also unveiled its "all-in-one-solution," a 500-MW FLNG power plant that integrates a CCGT, an LNG containment system, and a regasification unit.

-Sonal Patelis a POWER associate editor.

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