Opinion

REINVENTING FUEL-BASED POWER FOR A MORE SECURE AND RESILIENT GRID

Toby Gill, CEO, Intelligent Power Generation

With battery storage able or peak during half time of a national to provide a unique televised sporting event. But what is role in balancing a difficult to predict is the localised and renewable electricity short-term variations in this projected grid, Toby Gill, CEO of demand. This is why balancing Intelligent Power Generation, asks could mechanisms are used to match supply innovations in green hydrogen and from the centralised power sources biofuel technologies contribute to a more with consumption at a local scale. optimised and economical energy mix? This varying demand on the electricity

The growth of global industrialisation, grid is managed by different balancing increasing demand on energy mechanisms, with some more suited to resources and rising carbon emissions specific changes in demand than others. are deepening the need for energy One example is diesel and natural gas infrastructure that is increasingly green, generators, that are plugged into local distributed, flexible, and resilient. transformers. These “dispatchable”

As our world becomes more connected, forms of power generation can respond more electrified, and more renewable, to changes in demand in as little as 5 not only are we increasing the demand minutes, making them suited to balance on our energy systems, but we are also those difficult-to-predict peaks. fundamentally changing the way they operate. We are transitioning from a demand-led OUR GRID IS CHANGING, energy system, where power generation can AND SO MUST THE be easily turned on and off to match demand, WAY WE OPERATE IT to one that is led by supply from variable and inflexible sources. As a result, grid balancing is now becoming more complex, whilst resilience and reliability all the more important. The challenge, now, is in establishing a renewable energy mix that can effectively and economically balance supply and demand season-by-season, week-by-week, hour-by-hour and second-by-second. So how is our grid changing, given our drive towards renewable power generation and the decarbonisation of our energy systems? Increasingly, wind and solar are replacing fossil fuels as our principle source of energy. They not only afford us some of the cheapest energy we can produce but also a route to the lowLOCALISED BALANCING IS NOT A NEW PROBLEM carbon power necessary to achieving global decarbonisation targets. These renewable energy sources,

Grid balancing and resilience is not a however, are fundamentally distinct challenge borne out of our transition to a from our traditional forms of power net-zero carbon economy. It is, however, a generation. The power outputs of wind challenge that is being made all the greater and solar are intermittent, fluctuating as we continue to decentralise power according to real-time availability, whilst generation with more distributed, variable and infrastructure must be built in specific inflexible sources, such as wind and solar. locations. This creates an energy system

Grid balancing is about ensuring electricity more variable and more distributed supply meets demand second-by-second, than we’ve previously operated. by regulating properties including power, We are no longer working with voltage and frequency. This is to ensure that an energy system that can be led electricity is always there to safely power only by predictions in demand, everything from industrial plants to the but one that needs to establish a wall sockets in our homes and offices. new set of mechanisms that can

For grid operators, the macro trends in effectively and economically balance power demand can be easy to predict, and this demand uncertainty with a therefore easier to balance. For example, newfound uncertainty in supply. demand will often increase when is it raining

WHAT ARE THE MECHANISMS WE NEED TO BALANCE A RENEWABLE GRID?

100% WIND AND SOLAR IS NOT FEASIBLE ON ITS OWN

There is more than sufficient wind and solar power potential to exceed demand. In Europe, for example, on- and off-shore wind energy potential is estimated to be ten times greater than the annual demand.1

It is argued, therefore, that with this power potential, we can create enough excess in wind and solar power that the statistical likelihood of not having the power supply to match demand is effectively zero. However, wind and solar generation is location specific, and it is not as simple as transmitting wind power from Scotland to power homes in London.

With the yearly average of wind power in the UK at around 30% of power potential,2 at first glance, it may seem we only need 3-4 times as much infrastructure to ensure we have the minimum power requirement for the nation. But, if you look a specific areas in the UK, take London, the daily wind power output could be far lower, and therefore the need will not be 3-4 times, but far greater.

In this scenario, therefore, we would have to vastly oversize our wind and solar infrastructure to ensure we can deliver the absolute minimum power requirement for those worst case scenarios.

1 Swart, R. J., et al. Europe’s onshore and offshore wind energy potential, an assessment of environmental and economic constraints. No. 6/2009. European

Environment Agency, 2009. 2 Renewable UK, Wind Energy Statistics

Explained, available at: https:// www.renewableuk.com/page/

UKWEDExplained#:~:text=The%20load%20 factor%20is%20calculated,onshore%20 wind%3A%2026.62%25, accessed 12th

November, 2020

BATTERY STORAGE CAN OPTIMISE THE ENERGY MIX, BUT IS ALSO LIMITED

We are all becoming increasingly familiar with the narrative that, energy storage is the solution for balancing a distributed and renewable grid, therefore reducing the need for vastly oversized infrastructure.

Batteries are one mechanism for doing this, as they store power, when wind and solar generation outstrips demand, and use this to balance the grid when demand outweighs supply. They also have the unique ability to discharge power within the millisecond, and effectively balance the second-bysecond variations in output. A fuel-based generator cannot turn on quick enough to respond to these types of changes.

But, to solve the week-by-week or season-by-season variations with batteries is to follow the same route as a 100% wind and solar powered grid. Again, to scale battery storage to store the weeks and weeks of power needed to balance the grid in those situations would result in huge infrastructure requirements.

Therefore, in the scenario above, batteries enable you to significantly reduce the oversizing of wind and solar infrastructure, whilst ensuring the minimum power requirement. But in those longer timeframes and locations farther from energy sources, the question becomes: is a system that only has wind, solar and battery

storage the most optimised and economical one we can create? HYDROGEN AND BIOFUELS OFFER ANOTHER FORM OF RENEWABLE ENERGY STORAGE TO FURTHER OPTIMISED OUR ENERGY SYSTEM

Wind, solar and battery storage are not the most optimised solution, not when we have a route to netzero, demand-responsive power with fuels such as hydrogen and biofuels. These renewable fuels can be a more energy dense and more costeffective energy storage medium for balancing supply and demand not just in those longer timeframes, but across the spectrum of intermittency.

The challenge in using renewable fuels today is twofold. Firstly, the timelines to the abundant availability of renewable fuels that are economical to produce and environmentally sustainable is uncertain. This creates risk around investing in fuel infrastructure today that could become redundant tomorrow. Equally, any technology currently available, for burning these renewable fuels, uses a flame during the combustion process, producing the pollutant emissions that are harmful to human health.

We need, therefore, technologies and solutions that offer fuel-flexibility in order to de-risk the transition to renewable fuels, as well as ones that do not compromise our clean air ambitions. Hydrogen fuel cells go some way to answering these challenges, but breakthroughs in flameless combustion and low-cost, high-temperature ceramics offer an alternative solution.

We can, then, continue to use the localised dispatchable power generation that we have always used but do so with renewable fuels. As with batteries, renewable fuel-based power offers a further opportunity to optimise our energy system and reduce the total amount of infrastructure needed.

A HYBRID SYSTEM OF WIND, SOLAR, BATTERIES AND RENEWABLE FUEL-BASED POWER IS THE SOLUTION FOR A RESILIENT, OPTIMISED AND STABLE ENERGY SYSTEM

As the world strives to decarbonise and mitigate our climate impact, one of our key goals is to ensure sustainable, secure and affordable energy. Renewable fuels, and innovations in the technologies that operate them, offer a road map to reinventing fuel-based power generation to help achieve this future. An energy system that uses wind, solar, battery storage and renewable fuel-based power is not only more optimised and stable, but one that is decarbonised and affordable too.

Let us not, therefore, discard fuel-based power as a tool of the past, but one that can evolve to help us achieve a resilient and secure net-zero future. www.inpowergen.com

MONITORING & METERING POWER FACTOR CORRECTION: FIT IT BUT DON’T FORGET IT!

Power factor correction is essential if you want to ensure that you only pay for energy that you actually use – but that doesn’t mean it’s something you can simply fit and forget, cautions Julian Grant of Chauvin Arnoux.

In this series of articles, we’ve already itself – as many variable discussed power correction but there’s one speed drives are carefully aspect we haven’t covered in any detail: the designed to minimise importance of ensuring that your power harmonic production – but factor correction system will continue to this suppression isn’t always operate correctly – and safely – when you completely effective and it’s not at all install additional plant or update existing unusual for harmonics to find their way plant. This is a key topic: get it wrong and you into a factory distribution system. could end up with costly equipment failures But what does that have to do with as well as unnecessarily high energy bills. power factor correction? To answer Before explaining further, let’s quickly that question, remember first of all that recap what power factor is all about. Electric harmonics are currents and voltages at motors and many other types of load draw whole-number multiples of the supply both active and reactive power from the frequency – 100, 150, 200, 250, 300 Hz supply system. You pay for both types of and so on – for a 50 Hz supply. Then power, but it’s only the active power that does consider that power factor correction useful work by driving a motor for example. relies on capacitors but is always used in

Reactive power does nothing useful at all, so circuits where inductance is also present. by paying for it, you are simply wasting money. Finally, remember that when capacitance Reactive power can be either ‘lagging’, and inductance are present in a circuit, which is associated with loads that, like it will, at some frequency, be resonant. motors, are predominantly inductive, or If the resonant frequency of the

‘leading’ which is associated with loads that are power factor correction system happens predominantly capacitive. Lagging and leading to be the same as the frequency of reactive currents cancel each other out but, one of the harmonics, there’s trouble in almost all installations, lagging currents ahead! Large currents will flow in the predominate. Power factor correction systems capacitors leading to heating and, in compensate for this by adding capacitors, the worst cases, to their failure and and if they’re properly designed, they can even destruction. This is by no means reduce reactive power to almost zero. a theoretical issue; cases of this type Power factor correction can be fitted are becoming increasingly common as on a load-by-load basis, but a far more businesses update older plant that used common solution is to fit a single power simple starters, such as direct-on-line factor correction system serving a whole and star-delta types, by fitting variable site or a whole department. Many factories speed drives that, in many applications, and commercial sites have these systems are much more energy efficient. installed and, because they need only minimal What’s the solution? The crucial maintenance, they’re often almost forgotten. part of the answer is never to forget

This is bad news, because capacitors can about your power factor correction lose capacitance over time, which means installation. Even if you are not extending they’re no longer able to provide the expected or modifying your plant, check it regularly, level of correction. As a result, reactive using a portable energy logger, to make power goes up and so do the energy bills. sure that it’s still working effectively. And, This is bad enough, but there are if you are carrying out work on your plant, potentially far more serious issues that arise be sure to carefully monitor harmonic if you are installing new plant or updating levels before and after you make the existing plant. This is because the new or changes, along with the currents that are updated plant is very likely to incorporate being drawn from the supply system. non-linear loads, like variable speed drives You should also ensure that your and switch-mode power supplies, and power factor correction system is non-linear loads produce harmonics. These ‘detuned’ which means that it has may be well suppressed within the load been designed so that the resonances

created by its capacitive and inductive components do not coincide with any of the harmonic frequencies. This will probably be the case when the system was new, but don’t forget that, as capacitors age, they tend to lose capacitance and it’s possible that this may shift the resonances so that they become problematic. So even if you haven’t made changes to your plant, ageing capacitors in your power factor correction installation can lead to excessive harmonic currents – regular checking is important!

A good portable energy logger, such as the Chauvin Arnoux PEL103, will tell you all you need to know about harmonics in your supply system. The best types are easy to use and, in many cases, can be connected without the need to turn off the power. Note that it’s a good idea to leave the PEL in place for at least a typical working day, and if possible, longer, to be sure that data relating to all the operating conditions of your plant have been captured. Should you find that harmonic currents are exceeding acceptable values, additional harmonic mitigation measures will be needed, but these will be a lot less costly and lot less disruptive than failure of your power factor correction system.

Power factor correction is an essential requirement for every energyconscious business. It is important, however, to check from time to time that the power factor correction system is still doing its job and it’s absolutely essential to make sure that it is capable of operating reliably and safely when any major plant modifications or extensions are carried out. Investing in a modern PEL will make it easy to meet these requirements but, should you need further advice or guidance, the technical experts at Chauvin Arnoux will be pleased to help. www.chauvin-arnoux.co.uk