Baseload, DER, Microgrids, Microgrids, Off-Grid, Solar, Storage, Wind Power

Modular Power and Renewables

Issue 2 and Volume 21.

Pairing renewable energy with diesel and gas-fired generators to electrify remote and hard-to-access regions all over the world is helping increase energy access and beefing up clean energy competitiveness.

With abundant free energy sources such as wind and solar power just waiting to be harnessed, it is unacceptable that areas of the world have intermittent power or no power supply at all. Fuel flexibility creates opportunities to bring electricity to these areas.

Mockup of the Statoil/Aggreko Batwind project that will add Younicos batteries to the Hywind floating wind farm in Scotland. Credit: Statoil.

Mockup of the Statoil/Aggreko Batwind project that will add Younicos batteries to the Hywind floating wind farm in Scotland. Credit: Statoil.

Fuel flexibility might be a matter of reducing the pressure of a gas supply, turning flare gas into power, or it could mean creating a hybrid generation source that seamlessly switches between solar, wind or hydropower plus a robust, uninterruptible generator powered by gas or diesel, to bring round the clock reliable electricity.

“Flexibility is the name of the game,” said Dan Ibbetson, Aggreko Group Business Development Director. “For us, it’s about finding a way to bring power in the most efficient, cost effective and convenient way to the customer and that means thinking out of the box.”

Aggreko was founded more than 50 years ago, originally renting diesel, then gas, generators to more recently offering generators that can run renewable fuels.

“We change and adapt to meet changing needs, so if a customer has high pressure gas, we work hard to find a way to use that gas. The same is true of other available resources,” said Ibbetson.

The fall in the price of solar in recent years has made solar generated power a viable solution for countries, communities and industries. However, the sun doesn’t shine 24 hours a day, and even in the regions with the highest insolation, clouds and other weather unpredictability make PV an unreliable standalone fuel source.

That’s where hybrid power comes into its own, and a mobile, modular power package, such as what Aggreko offers, brings a number of benefits.

Renting energy means that companies, whether government utilities or remote independent businesses, save time and money. It means their capital is not tied up in equipment that can sometimes take years to be delivered and brought online, and because they don’t own it they don’t have to service and maintain it. They just pay for what they use.

A rented energy arrangement frees up capital that can then be ploughed back into the business. For instance, Peter Yealands of Yealands Winery in New Zealand estimates that he saves $1 million a year by renting energy instead of buying the power equipment he would need to run his winery.

Aggreko offers a solar-diesel hybrid package, such as the 30-MW system it is currently supplying to Eritrea, which comprises 7.5 MW of solar power, supported by 22 MW of diesel generated power. The company estimates that this solution is saving around 20 percent of the fuel costs of diesel-only power. Because the systems are mobile and modular, the ratios can be amended, as demand dictates, and scaled up or down according to need.

Innovations in Offshore Wind + Batteries

Wind generated electricity can also be paired with other generation sources. Aggreko helped Statoil commission the world’s first floating wind farm, Hywind, 15 miles off the north-east coast of Scotland in the fall of 2017. Aggreko-owned battery storage company, Younicos, has plans to install the first battery storage system to the floating wind farm in 2018 in a project called Batwind.

Aggreko 100-MW temporary power system installed at a utility site in Mozambique. Credit: Aggreko.

Aggreko 100-MW temporary power system installed at a utility site in Mozambique. Credit: Aggreko.

Hywind comprises five 6-MW turbines, tethered to the seabed via an anchor, instead of sitting on the traditional monopole drilled into the seabed. Monopiles take months to construct and can generally go to a maximum depth of about 50 meters, which limits how far out to sea they can be located. Floating turbines can be anchored in depths of up to 800 meters, which Statoil estimates could open up 80 percent of the world’s deep continental shelves to offshore wind energy.

In this case, it was the collaboration between Statoil and Aggreko that made this offshore floating wind farm possible. The turbines have a power demand of around 5 to 10 kW, but when their on-board pump starts up the demand shoots up to 50 to 60 kW in a matter of seconds.

This sudden demand creates a sharp power spike that can immediately shut down a generator if it’s not powerful enough to cope with the surge. The turbines would require a 125-kVA generator, which is too big and heavy for the turbine, so Aggreko proposed the idea of a soft start to create a gentler demand curve.

As a result, each 6-MW turbine now has its own onboard 60-kVA Aggreko generator that controls a number of vital functions, including lighting, heating and dehumidification, pitching and yawing controls, as well as the pump. A 60-kVA unit is nearly half the weight of its 125-kVA brother, so it can be lifted by the turbine’s Davit crane and sit comfortably on the man access platform.

In addition, the 60-kVA generator consumes less fuel, so it is much more economical to run. Aggreko’s equipment is fitted with proprietary real-time data monitoring, which we call ARM (Aggreko Remote Monitoring), so refuelling, inspections and overall operations and maintenance can be done at longer intervals, and from a standard crew vessel.

Considering it takes 30 minutes for a crewman just to climb up and down the turbine, and with five in this wind farm, ARM is saving considerable man-hours looking for potential issues, checking fuel levels and refuelling.

In addition to the on-board generators that help power the floating wind farm, other innovations using batteries and wind power are also under investigation.

Later this year, Younicos will install two Y Cubes, 10-foot modular battery containers, at the Hywind substation in Peterhead, Scotland to understand how the batteries can help increase the wholesale value of wind-generated electricity when it is sold onto the grid.

The installation includes Younicos’s YQ software, which is the brain that ensures the battery knows when to hold back and store electricity, and when to send it out to the grid based on price signals it will be set to receive.

Hydropower and Battery Storage

Droughts are occurring in areas of the world that rely on hydropower so a back-up of a diesel or gas hybrid package can give utilities peace of mind knowing that they can fulfil their contractual obligations to their customers and not leave households, schools, hospitals and manufacturing businesses without power.

Aggreko also works with hydro and stepped in to bridge the gap in power availability that resulted from the failure of the Basslink interconnector between Tasmania and the Australian mainland.

“Combining renewables with traditional energy generation creates the opportunity to bring power where it would otherwise have been unavailable,” said Aggreko Chief Executive, Chris Weston.

“We have always believed in the opportunities that power delivers. Nothing happens without power, and that is unacceptable, anywhere in the world. Renewables are certainly the future, and we are happy to look at any technological advancement that helps bring power to the world.”

Liz Fullick is the group content manager at Aggreko.