Carbon-Cutting Floating Wind Generators Power Microgrids for Oil and Gas Rigs
When oil and gas companies are looking for microgrids to power their offshore rigs, offshore wind has generally not been a technology of choice.
Traditionally, oil and gas installations have used gas turbine generators to generate the electric power needed to run their drilling operations, which require several hundred megawatts for heating, pumping and processing. Many of these operations are also gas producers. Gas is readily available, so it’s an easy choice.
The industry sometimes uses solar. For example, ABB plans to install a solar plus storage microgrid for a platform operated by Australia’s largest independent oil and gas company to replace existing gas turbine generators.
A few pilot projects involving wind farms have been created, but they’re all connected to onshore grids.
Odfjell Oceanwind plans to change all that with its WindGrid technology for microgrids. These are mobile offshore wind units, 11 MW each, that serve microgrids powering oil and gas rigs. Odfjell’s focus right now is on renting the units in the North Sea, especially in Norway, which has ambitious goals for reducing carbon dioxide emissions. The region also has high carbon taxes and excellent wind year-round, said Per Lund, CEO of Odfjell Oceanwind, which is based in Norway and develops, owns and operates floating mobile offshore wind units for microgrids.
Savings outweigh costs
In Norway, being carbon-intensive is costly because of the fees and taxes levied upon emitters. The sum of the national carbon dioxide fee and the European Union’s carbon-cutting fee is now above $100 (US dollars) per ton of carbon dioxide, he said. The Norwegian government has proposed increasing that figure to $220 (US dollars) per ton by 2030. The goal is to cut emissions 55% by 2030.
“The total monetary savings from saved fuel and taxes normally outweighs the additional cost of the rental wind turbines,” said Lund.
The company says its technology reduces carbon dioxide emissions by 70% compared to what conventional fossil fuel generators emit. This is double the emissions reduction provided by conventional wind farms because there’s more wind offshore to harvest. That statistic was recently confirmed by an independent verification review conducted by DNV, an accredited certification body based in Norway that certifies compliance of companies to third-party standards.
“Being an owner and operator of large floating assets ourselves, through Odfjell Drilling, we fully understand the criticality of making such a radical change in the power management philosophies,” said Lund. It was important for the company to have a recognized third party verify its technology so that clients would trust the company’s products, he added.
Wind turbines are the best option for serving offshore rigs because wind is easy to harvest in the ocean, said Lund.
Drawbacks of other options
“We have looked at waves, ocean current and solar, but they all come with their particular challenges in rough waters like in the North Sea,” said Lund. Wind resources offshore are better than onshore and coastal wind resources, he added. “Another key to getting the most out of the wind power is our WindGrid solution gives you sufficient grid stability to stop the gas turbine generators in periods with wind power production.”
Odfjell Oceanwind’s technology combines energy storage, grid converters and floating wind turbines to allow for the shutdown of offshore gas turbine generators during peak wind power production. The offshore wind turbines provide power to oil and gas platforms that are used for the drilling, processing and export of oil and gas. Odfjell’s sister company, Odfjell Drilling, helped develop the technology for its fleet of mobile offshore drilling units.
Solar is generally less attractive for offshore drilling operations because it requires large areas.
“For installations in offshore locations in harsh environments, such areas are scarce and very expensive. Solar is only used at a very little degree,” said Lund.
Rental model
The typical microgrid on a platform includes two or more gas turbine generators. On the platform is energy consuming equipment, including pumps, compressors, and heat and ventilation, said Lund. The microgrids are typically located several hundred miles from shore. The microgrids can be fixed to the ocean floor or floating, and sometimes numerous installations are connected into one grid.
“Basically they are large oil and gas processing factories in the ocean, many times with hundreds of people commuting to and from with helicopters,” said Lund.
The company’s business model is to own and operate the floating wind turbines, and rent them to clients who can pay either by the day or by the kWh. Lund said that renting is more attractive to clients because they only need the units for five to 15 years before the oil and gas installation is decommissioned.
“In many ways our rental model is energy as a service,” he said. Odfjell prefers to customize the configuration for each customer to maximize the value proposition, he added.
Not just for oil and gas rigs
The floating wind turbines aren’t only appropriate for oil and gas rigs, but any application that has high power needs and is close to deep water and high wind resources. That might include island communities and large offshore fish farms.
Offshore wind units yield more wind power and require less space than solar. But they’re also attractive because they’re less likely to conflict with fisheries in offshore locations, compared to onshore and coastal wind installations.
“Our main potential conflict of interest is with fisheries, so we try to pick locations that are of less interest for the fishermen. Other than that, we have to ensure that we don’t lay our anchors and mooring in seabed corals and avoid bird migration routes,” said Lund.
By renting its wind units to microgrid users, the company aims to help curb the oil and gas industry’s carbon emissions in Norway and across the world. The floating wind turbines will allow the oil and gas industry to move toward a “green shift” more quickly and cost effectively than with other technologies, including wind power based onshore, said Lund.
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