11 minute read
Energy Storage, Standby Power & UPS
How standby power is evolving in step with carbon reductions
Kelly Cole, General Manager for Finning UK & Ireland’s energy and transportation division and exclusive dealer for Cat engines and generators, provides an insight into what’s been ongoing for some time across the supply chain, with options both for the here and now and for the years to come.
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tandby power generation plays a critical role across many different applications, in the instance of a mains outage or unpredictable supply – such as keeping vital hospital equipment functioning, maintaining operations at utility plants and ensuring data centres stay online.
At present, the most common fuels used in backup generators are gas and diesel. So, although much discussion on the energy transition is focused on how we move away from the use of fossil fuels for mains power, if we are to truly achieve net zero carbon then the industry needs to ensure that standby power can also be produced through low and, ultimately, carbon-free means. Ensuring reliability Current reliance on diesel generators for standby power is well established, primarily because of their practical benefits. They are readily available, reliable as a mature technology and able to quickly ramp up to seamlessly cover issues with mains power supplies.
Given that high-profile standby power users, such as hospitals and data centres, must mitigate any risks that may be posed to maintaining mission critical services, the advantages in terms of reliability that existing technology offers must be carefully considered as we transition away from fossil fuels.
Indeed, in these understandably risk-averse sectors we are likely to see a phased transition to a balance between maintaining the
benefits of existing technology with the importance of using carbon-free energy.
HVO proving a smart first step A first step in this transition is the growing use of Hydrotreated Vegetable Oil (HVO). Produced from certified waste fats and oils, HVO is manufactured using a synthesised process with hydrogen to offer a more sustainable alternative to fossil fuels. Although not entirely carbon-free, HVO can eliminate up to 90% of the carbon emissions compared with the production and use of conventional diesel.
Another key advantage is that it can be used as a drop-in replacement for diesel in many engines, as well as used with existing diesel or biodiesel stocks. For example, provided the fuel meets standard requirements, Cat generators built after the year 2000 are able to run on HVO.
Given the ease with which they can be integrated into existing assets, we have seen growing interest in the use of HVO in tandem with diesel to lower the carbon footprint of standby generators.
Whilst the use of HVO with conventional diesel has been the most common approach, there have been high profile cases where a move to 100% HVO has been taken – allowing even greater reductions in carbon emission. Last year Microsoft announced that all Cat generator sets at its new data centres being constructed in Sweden would run on HVO, providing the final element to obtaining all of its energy needs from renewable sources.
“We have worked extensively to ensure that our new data centres in Sweden will be among our most sustainably designed and operated in the world,” observes Noelle Walsh, Corporate Vice President, Cloud Operations and Innovation at Microsoft.
“Caterpillar and the Cat dealer network have developed innovative power solutions that support Microsoft and our unwavering commitment to carbon reductions. Cat generator sets at Microsoft data centres help us keep availability promises to our customers even when grid power fails, providing continuous energy and uninterrupted cloud services.”
In short, with largely immaterial differences in performance and consumption in comparison with diesel, HVO provides an excellent next step to reducing carbon emissions. Crucially, it offers flexibility with any HVO to diesel ratio between 0% and 100% possible depending on the specific demands and preferences of each project.
Longer-term benefits of hydrogen Whilst HVO is a convenient and highly effective drop-in replacement for existing diesel equipment, it is not entirely carbon-free. Furthermore, the sheer scale of demand for fuel means that it is unlikely to become a permanent solution due to its production being limited by how much vegetable oil and fat is available globally.
Hydrogen has been touted as a more likely long-term solution, with advances in blue (the splitting of natural gas into hydrogen and CO2, with the resulting carbon captured) and green (splitting water by electrolysis into hydrogen and oxygen) production set to help create the volumes needed to replace fossil fuels on a global scale.
Whilst those production volumes are yet to come, plans are in action and it is an area that should be explored when looking at the next generation of sustainable equipment. As with HVO, a blended approach may be the likeliest next step with gas gensets configured to allow for a blended fuel containing up to 25% hydrogen.
Manufacturers such as Caterpillar are rolling out gas generators configured out-of-the-factory to enable operation on natural gas blended with hydrogen. Adaptation of existing gensets can be done with the use of retrofit kits for some equipment, making it an appealing quick win as hydrogen availability increases.
Rising industry interest and development of hydrogen supply infrastructure means that 100% hydrogen gensets are in advanced stages of development and we will likely see trials of this equipment in the near future.
Where next? A critical consideration in taking the next step to HVO or potentially hydrogen is the partner selected to help with this transition – particularly where there are high risks involved should the move not go smoothly. Working with a specialist will allow operators to benefit from experience of similar projects both across their own sector and further afield. This will help to ensure carbon emissions are minimised without compromising on uptime.
How to unlock the true power of your UPS
Jason Yates, Technical Services Manager at Riello UPS, explains how rethinking the role of uninterruptible power supplies can transform them into ‘virtual power plants’ that aid the ongoing energy transition.
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ith soaring energy costs never too far from the headlines in recent months, electrical systems throughout the world continue to evolve. The shift from fossil fuels to renewables is a necessary one on the journey to zero carbon. But a consequence of this ongoing energy transition is that system operators such as National Grid now face a much trickier task to balance supply with demand and ensure a stable grid frequency.
Rather than simply controlling power generation to meet demand, as we’ve done in the past, the power grids of the future will be smarter and more flexible, with demand controlled to meet supply in real-time.
Energy users will become producers too, with electricity flowing in both directions as they not only draw power from the grid but also feed stored energy back into it.
Concepts such as demand side response, which incentivise customers to store power and shift energy use from busy to off-peak times, also offer organisations the opportunity to reduce their eye-watering electricity bills.
But it will require a significant shift in mindset to take full advantage.
From underutilised asset to virtual power plant From the data centres that are crucial to our digitally-driven lives, through to factories, shopping centres, and processing plants, virtually any facility with a critical electrical load will have uninterruptible power supplies (UPS) and
batteries installed to protect against damaging downtime.
Fortunately though, major power cuts in the UK are relatively rare. So, while a UPS is undoubtedly an essential insurance policy against the worst-case scenario, in some ways they’re an underutilised and expensive asset. And if the batteries aren’t being used regularly, can you be 100% sure they’ll actually work if and when you really need them to?
Thanks to advances in communications software and protocols, along with the development of premium cycle-proof batteries, many modern UPS systems are now smart grid-ready. They can communicate with local power networks and either draw electricity from the grid or push stored energy back into it, depending on the real-time requirements.
These characteristics have the potential to transform your UPS from a reactive piece of hardware into a dynamic ‘virtual power plant’ that can contribute to the ongoing energy transition and profit from the energy markets, whilst also benefiting from enhanced reliability.
Putting theory into practice As an example, we teamed up with RWE Supply & Trading, one of Europe’s leading energy trading companies, to develop Master+, a smart grid solution specifically for data centres and other large-scale energy users.
It comprises a highly efficient, smart grid-ready UPS backed with cycle-proof premium lead-acid batteries (NB lithium-ion batteries are a viable option too). Thanks to a compact battery arrangement, the system is able to provide up to four times the usable capacity but with only a 20% increase in footprint, so enough battery capacity for both emergency backup and for commercialisation.
The solution also has an integrated, highly-secure control and monitoring system that enables two-way communication with the grid and aids with predictive maintenance.
The battery system is split virtually into two separate parts. There’s a backup segment representing around 30% of the total usable capacity. This element is configured and controlled by the UPS and is preserved only to support the critical load in the event of a mains failure.
The remaining 70% of the battery capacity is the ‘commercial’ segment, which RWE can deploy to participate in grid balancing schemes such as Firm Frequency Response (FFR). This is a demand side response mechanism National Grid operates to help maintain a consistent and safe grid frequency within one hertz of 50 Hz.
So in practice, if the frequency increases above 50 Hz, the UPS effectively draws power from the grid into the battery system to help pull the frequency back down. On the other hand, when the frequency falls below 50 Hz, we push the power stored in the commercial segment of the batteries back into the grid.
The typical state of charge during system operation fluctuates between 60-70%. Therefore, if there is a mains failure, the site would benefit from extended backup autonomy because whatever energy is left in the commercial segment tops up what’s already in the guaranteed backup segment.
So in return for RWE gaining the usage rights for the commercial segment of the battery, the site owner benefits from a significantly discounted battery system, extended backup time, 24/7 monitoring, lower ongoing maintenance costs, and reduced grid tariff charges, which depending on the site can potentially be worth up to £6,000 per MW per year.
Potential of peak shaving Peak shaving is another potential function of a smart grid-ready UPS. In practice, this is using the UPS batteries to effectively limit how much power is taken from the mains supply. If the load on the UPS output goes beyond a set level, then the UPS takes a proportion of the load from the mains, with the remainder coming from the batteries.
There are four main types of peak shaving. Firstly, there’s static, where the UPS has a fixed setting and peak shaves to that defined limit. There’s also user-controlled, where the facility can reduce the input power ad-hoc by pushing commands to the UPS using volt-free contacts or protocols such as Modbus.
There’s also impact load buffering, which is predominantly for sites with a weak power source or generator and sees the UPS in effect slow down the incoming mains supply. Finally, and probably the most commonly used, is dynamic peak shaving, which as the name suggests, works according to the real-time on-site conditions.
How does this work in practice? Say you’ve got a site that is contractually limited to 1 MW of mains supply. Its typical load ranges between 500-900 kW, while they have a critical load of another 300 kW. Potentially, that’s a maximum load of 1.2 MW, which would be in breach of their contract.
During these peak load periods, the UPS automatically pushes the energy stored in its batteries to reduce the power required from the mains. And of course, when loads are lower, the UPS recharges the batteries for future use.
In addition to frequency response and peak shaving, smart gridready UPS can also carry out other valuable functions, including voltage optimisation, which guarantees a stable voltage (i.e. 400Vac + or -1%) no matter the incoming mains supply, and waveform correction, which reduces the harmonic distortion on the load and improves the overall power factor.
Unlocking the value of battery power It’s clear that modern UPS have much more to offer than just sitting and waiting to provide emergency backup power.
Just a few weeks ago, tech giant Microsoft announced its data centre UPS across Ireland would start using lithium-ion batteries to feed power back into the grid by the end of the year. This battery power will reduce the reliance on coal and gas-fired plants to maintain spinning reserves, helping to significantly reduce the Irish energy sector’s CO2 emissions.
As smart grid technology continues to improve, there are similar opportunities for other facilities to follow suit and harness the true power of their UPS systems and batteries. Not only do you reap the financial and performance rewards, but it’ll also help with the security of supplies for society as a whole.
