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Power to the people
In an oversupplied natural gas market, one major contractor is floating a concept that uses offshore oil and gas technologies to provide vital resources such as drinking water and affordable power to coastal communities.
Adding water treatment and power generation functions to a floating storage and regasification unit (FSRU) may be a more economical way to supply water and power than building onshore facilities, according to FPSO specialist Modec.
About a decade ago, Modec was participating in front-end engineering and design (FEED) work for proposed floating LNG projects.
More recently, with oil and gas prices depressed, a glut of LNG expected to come on stream and no imminent sign of a price recovery, executives at Modec went on the hunt for new opportunities.
“We have a lot of power generation capacity installed on our vessels, but we had no idea how much until we asked someone to sit down and write it down,” says Dan Winkler, who leads Modec’s business development for gas projects. That number came out to 1.5 gigawatts of power installed on the company’s fleet of 18 floaters.
"We realised a lot of people don’t have access to clean water, they don’t have access to power."
“We had no idea how much water we were producing either,” says Puneet Sharma, vice president of the project development group.
Turns out Modec is treating 328,000 cubic metres (86 million gallons) of sea water per day, equal to more than 130 Olympic-size swimming pools.
“We realised a lot of LNG will be coming on the market that needs an outlet. What can we do with the LNG?” Winkler says.
“We realised a lot of people don’t have access to clean water, they don’t have access to power.”
In November 2015, Modec seized on the idea of the Floating Storage Regasification Water & Power (FSRWP) vessel as a way to supply power and water to coastal areas, given that a large percentage of the world’s populations lives within 160 kilometres of an ocean or river.
By April last year, Modec had run the idea past officials in several African countries to check viability and interest.
The company invested a couple of million dollars into research and development, and by end of 2016 had evaluated 13 potential hull forms, developed three basic sizes of the FSRWP and refined cost estimates for the solution.
The six-month in-house FEED is complete, and Modec is working with DNV to get approval in principle in place, which is expected by the middle of April.
Sharma says the company is taking a bit of a hiatus from the FLNG side of the business, given market conditions, but that the FSRWP is an alternate product that uses many of the same technologies required in FLNG operations.
“There is a market for floating power generation regardless of whether the FLNG business picks up,” Winkler says. “This could be a new product line for Modec.”
Sharma says that by combining the power generation and water treatment efforts on a single vessel, the company estimates it can reduce the cost of each by 30% to 40%.
“We could seriously interrupt this market,” Winkler says.
Modec is offering three designs and three size options. The three designs are power only, water only, and power and water combined.
Of the three sizes, the smallest is intended for use in rivers or mangrove swamps. It would be a shallow craft capable of providing between 84 and 172 MW of power.
According to Energy Information Administration, the average US household consumption in 2015 was 10,812 kWh per year.
Based on that number, Modec estimates one of its 120 MW FSRP systems can supply around 94,300 US households with electricity based on the 2015 consumption rate and 97% availability of the system.
The medium size vessel will be able to provide capacity between 86 MW and 472 MW per day.
“We think this is a sweet spot solution,” Sharma says.
The large solution could provide 240 to 1000 MW of power per day.
The small vessel would be a newbuild barge, while the other two sizes could be conversions or newbuilds. All would have a planned 20-year design life unless specified higher. And all will have integrated LNG storage systems.
“What’s different from an FPSO is the LNG containment and handling systems,” Winkler says, adding the unit would also have a larger power generation package compared to what might exist on an FPSO or FLNG unit.
The topsides also would not need to accommodate hydrocarbon production activities, freeing up room for the power and water packages.
Sharma says the crucial technologies that make the FSRWP viable are the subsea electrical cable, the electrical swivel and the combined cycle power generation system.
The solution will require one subsea electrical cable per 100 MW of power generated to send power to shore, while water would flow through pipelines.
“There are multiple topside layouts,” Winkler says. “We’re using different generators, different combinations of generators.
"It was an extensive exercise just to find out the maximum megawatts we could install on each type of vessel or barge, and to figure out the lowest possible kilowatt per hour cost.”
Modec plans to use combined cycle power plants for the FSRWP. In short, it uses the cold LNG to condense the steam created through power generation, and it uses the steam to gasify the LNG, which makes both processes more efficient.
Modec’s design calls for aeroderivative and industrial gas turbines to generate the power needed. This solution, in combination with LNG, will result in lower emissions.
Sharma says clients for the FSRWP may include utility companies, host countries, or oil and gas operators that have power divisions.
“We could market this to the oil industry and say, ‘we’ll lease this to your power division just like we lease the FPSO’,” Sharma says.
Winkler believes the FSRWP option will be attractive for a number of reasons, not least of which is the timeline.
An FSRWP can be in the water in 18 to 25 months after the contract award, he says.
Onshore power and water plants, on the other hand, can take three to five years, partly because of the lengthy permitting process.
Modec is working with GE and Dresser to marinise their power generation units.
“We’re just taking these things that our industry has worked on and making sure they’re suitable for his type of application,” Sharma says. “It’s not difficult to marinise. It just takes time.”