COP 26

COP26 round up: the path to coal-free

Clean energy future and resistors role

INDUSTRY’S NEXT STEPS TO A CLEAN ENERGY FUTUREI

The COVID-19 pandemic has shown the world how quickly global threats can take over, making this years’ Conference of the Parties (COP), COP26, the most imperative yet. As the world’s leaders debated how to limit climate change, phasing out coal power became a vital discussion point. Here Simone Bruckner, managing director Cressall, explores the energy goals made at COP26 and the technology that can help achieve them.

From the UK going coal-free for two months in 2020 to Venice’s canals clearing of pollution, restrictions during the COVID-19 pandemic had several positive effects on the environment. While these consequences were cause for short-term celebration, the pandemic highlighted the significant impact normal lifestyles and industrial operations have on our planet. 

In addition, despite temporary reductions in greenhouse gas emissions during the pandemic, the United Nations (UN) United in Science 2021 report found that their concentration in the atmosphere continues to rise. Alarmingly, the report also concluded that there’s a 40 per cent chance that average temperatures in one of the next five years will be 1.5 degrees Celsius warmer than pre-industrial times.

IMPORTANT TARGETS

It’s clear that, while much of the world’s operations paused during the pandemic, climate change continued. This placed particular importance on COP26, with some viewing it as the last chance to save the planet from climate disaster. The resulting COP26 agreement calls for countries to accelerate the phasing out of coal and subsidies for fossil fuels. This is a world first, as previous UN climate agreements have not specifically mentioned fossil fuels. 

In pledges made at COP26, more than 40 countries committed to transitioning away from coal. In order to phase out coal power, countries must increase the proportion of clean energy in their networks. This will not only require scaling up of renewable projects, but also incorporating technology that increases their efficiency.

RELYING ON RENEWABLES

For instance, solar tracking can increase the efficiency of solar panels by using motorised systems to move the panels so that they are always in direct alignment with the sun. This increases efficiency by overcoming a common issue seen with solar panels, where their power generation peaks at midday. 

Incorporating a solar tracking system can increase average solar panel power output by 35 per cent, and high efficiency can be further ensured by incorporating a dynamic braking resistor. In the motorised system, a dynamic braking resistor can be installed to dissipate the excess voltage of a decelerating motor. This makes sure that the motor doesn’t overshoot, which would cause the panel to land in a sub-optimal position.

Another renewable energy system that can benefit from additional technology is wind turbines. The majority of wind turbines use a doubly fed induction generator (DFIG), which enables them to operate at variable speeds. However, in exceptionally high winds, the rotor speed of a DFIG can exceed the maximum operating range of the system. This in turn can lead to high voltages that destroy elements of the system.

To avoid this issue and ensure high efficiency of the wind turbine system, a crowbar resistor can be fitted to the DFIG. Connected to the rotor windings of a DFIG, a crowbar resistor can prevent damage to the generator by disconnecting the converter when the rotor speed reaches its limit. 

RESISTORS TO THE RESCUE

With over 100 years’ experience in electrical engineering, Cressall is a trusted supplier of resistors to the renewable energy industry. For instance, our crowbar resistors for wind turbines can withstand high currents while remaining operational. In addition, our braking resistors for solar panels have no wearing components, so last as long as the panels themselves.

A commitment to phasing out coal power was a key outcome of COP26, and countries must increase their reliance on renewable energy if society is to bid farewell to fossil fuels. However, incorporating more clean energy into the network requires not only scaling up installation projects, but also taking advantage of advanced technology that can increase the efficiency of power generation. 

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Regenerative braking

WHAT IS REGENERATIVE BRAKING?

Imagine if you could reclaim some of the energy you lose throughout the day, without needing to rest. Did you know that electric vehicles (EVs) are able to do this through regenerative braking? An efficient way to reuse some of the energy lost as heat when a vehicle brakes, regenerative braking supports higher efficiency and the ability to travel further on a single charge.

When the driver steps on the brake pedal of a vehicle, hydraulic fluid pushes the brake pads against brake discs on each wheel. This friction slows down the vehicle, but the process also creates heat and wears away the material on the pads and discs over time.

Regenerative braking uses the excess kinetic energy to recharge an EV’s battery. It is able to do this because the electric motor in an EV can run in two directions: one, using the electrical energy, to drive the wheels and move the car, and the other, using the excess kinetic energy, to recharge the battery.

When the driver lifts their foot off the accelerator pedal and steps on the brake, the motor starts to resist the vehicle’s motion, “swapping direction”, and begins putting energy back into the battery. As a result, regenerative braking uses the EV’s motor as a generator to convert lost kinetic energy into stored energy in the battery.

A NECESSITY

The Competition and Market Authority has warned the UK government that, ahead of the petrol ban in 2030, more electric charging points must be established to make EV charging easier for road users. As it stands, there are only 25,000 public charging points in the UK. This needs to increase by tenfold to ensure EV success from 2030 onwards.

While not fundamentally an element of EV charging infrastructure, regenerative braking provides a way of making EVs more efficient by increasing the number of miles completed without charging the battery. Furthermore, the process can help make the charging less reliant on electricity from the National Grid. By reducing the frequency of charging and amount of electricity needed to recharge batteries, regenerative braking can make the entire charging process more energy efficient.

A HELPING HAND


However, regenerative braking cannot act alone. To work effectively, other technologies are needed to make the process safe and effective. If the car battery is already full or there is a failure, regenerative braking cannot happen as the excess energy has nowhere to go and must be dispelled safely. If not dissipated, it won’t be possible to slow down the vehicle. To prevent this from happening, resistors are used to collect excess energy and dissipate it safely.

Cressall’s EV2 resistor converts excess electricity into heat that can be dissipated or used in other parts of the vehicle, such as to heat the cabin, the batteries or even the fuel cell. The EV2 is a lightweight, compact resistor which manages to transfer this heat into the cooling water or glycol mix, which is already used in the cooling or heating system for different vehicle components. Cooling is achieved by pumping cold coolant liquid, which comes into one end of the unit and absorbs the heat through thermal conductivity and convection. It can then be pumped through a radiator located away from unit and cooled again to reach the starting temperature.

While it may not be possible for humans to regain lost energy without taking time out to recharge, regenerative braking enables EVs to use excess energy to work more efficiently. With the help of resistors, EV users can benefit from a longer battery life, helping to drive EV efficiency forward and ensuring safe driving in any conditions.

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Zero carbon transportation

ZERO CARBON TRANSPORTATION

HOW CAN AUTOMAKERS SUPPORT TRANSPORT’S DECARBONISATION?

In July 2021, the UK government unveiled its plan to decarbonise the entire domestic transport system to align with the net zero by 2050 target. All forms of domestic transport will be decarbonised on land, air and sea.

The electrification of the automotive market is a necessary step to reduce greenhouse gas emissions and ward off climate change’s consequences. Every automaker is in support of the rollout, with more affordable models being released by the day to encourage consumers to make the electric shift. At the same time, governments are enforcing change through legislation that bans the sale of new fossil fuelled vehicles from as early as 2025.

The Decarbonising transport: a better greener Britain report outlines how the government intends to achieve transport decarbonisation. While some of the report repeats previous pledges, it announces several new targets.

HOW HAVE THINGS CHANGED?

Since announcing its nation-wide net zero emissions by 2050 target back in 2019, it’s been common knowledge that the government wants all transport to decarbonise in the next few decades. One key initiative has been ending the sale of new fossil-fuelled cars and vans, which has been brought forward to 2030 — ten years ahead of initial plans.

In addition to bringing forward the ban on petrol and diesel cars and vans, the latest report also announces a ban on petrol and diesel heavy goods vehicles (HGVs) in 2040. This is an important step in decarbonising road transport since HGVs are some of the biggest carbon dioxide emitters, accounting for 17 per cent of road transport’s total emissions.

Although similar targets have been set for other transportation sectors, automotive is arguably in need of the greatest overhaul. The latest figures show that in 2019, the majority of greenhouse gas (GHG) emissions were from road transport. Therefore, we must take decarbonising this subsector as a top priority.

Despite significant progress, more needs to be done to create an electrified transport fleet. The electric vehicle (EV) market is growing at an exponential rate. According to data collected by the Department for Transport, Q1 of 2021 saw 73 per cent more battery electric vehicle (BEV) registrations than Q1 of 2020. With uptake ever increasing, automakers must address barriers to widespread adoption.

WHAT CHALLENGES DO WE FACE?

An extensive charging infrastructure across the UK will be needed to enable road transport’s decarbonisation, to meet consumer demand and to make EVs a viable option in all parts of the country. 

According to Zap Map, as of 21 July 2021, just under a third of all charging points were in Greater London, with more sparsely populated areas such as Northern Ireland accounting for just 1.3 per cent of all charging points. It is vital to tackle this disparity and ensure access to charging points is the same regardless of location to encourage EV uptake in rural communities.

HOW CAN TRANSPORT MANUFACTURERS SUPPORT THIS PLAN?

To support these goals, ensure compliance with fossil fuel bans and overcome these challenges, manufacturers must design vehicles and their components to facilitate decarbonised transport uptake.

EV2 modular resistor for electric vehicles

Cressall’s EV2 resistor is designed with the challenges of manufacturing EVs in mind. The EV2 is a dynamic braking resistor (DBR), which is an essential component of an EV. A DBR safeguards an EV’s power system by removing excess energy generated while braking. If the battery isn’t fully charged, this energy would be used to recharge the battery. However, when the battery is full or there is a failure, it’s vital to remove this excess energy from the system to prevent damage. A DBR dissipates it as heat, which can be used to warm the vehicle’s cabin or preheat the batteries too in order to achieve maximum efficiency.

The EV2’s flexible design makes it suited to every EV application. Its modular design means that up to five units can be combined in a single assembly to achieve a power rating between one kilowatt (kW) and 125 kW. Its extensive design range works up to 1500 Volts terminal to terminal and a resistance of up to 20 ohms (Ω) per single module. This flexibility means the resistor can be adapted to suit any automotive application — from small cars to large HGVs.

The government’s plan to decarbonise all domestic transport by 2050 will slash the sector’s contribution to total carbon emissions. With manufacturers’ support, this goal is achievable, accelerating the nation’s progress to net zero, reducing pollution and alleviating the damaging effects of climate change.

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Powering a coal-free future

IS THE UK’S COAL-FREE HIATUS HERE TO STAY?

Britain passed a significant landmark in June 2020, as the nation went for two months without burning coal to generate power. A decade ago, around 40 per cent of the UK’s electricity came from coal and, while the recent plummet in demand accounts for some of the success, it isn’t the full story. Simone Bruckner managing director of Cressall, explains why the country no longer depends on burning coal that has, for so long, been the backbone of Britain’s power.

Britain’s new coal-free period has smashed the previous record from June 2019, which lasted for 18 days, six hours and ten minutes. While that hiatus was caused by the unprecedented shutdown of many of the National Grid’s coal-fired power plants, the disruptions in 2020 have been even more remarkable. They are, however, by no means the sole contributor to coal’s decline.

RENEWABLES ON THE RISE

Two examples illustrate the recent changes in Britain’s power network. Ten years ago, wind and solar energy made up a meagre three per cent of the country’s power mix. Compare this to the first six months of 2020, where renewables were responsible for a significant 37 per cent of electricity supplied to the network — this outstripped fossil fuels by two per cent.

Secondly, a company that has historically been one of the biggest players in coal power appears to be moving on from its history. Drax, the UK’s largest power plant, was once the biggest consumer of coal in the UK. Now, the plant is making the switch to compressed wood pellets with the goal of phasing-out coal entirely by March 2021.

While some environmental activists still question the efficiency of burning wood, which still produces carbon emissions in its own right, this change would leave the UK with just three coal-powered plants.

WINDS OF CHANGE

There is one major reason why Britain’s 2020 shift away from coal power will have more longevity than a passing trend. That’s because renewable technology is far more sophisticated than it was ten years ago.

Renewable energy has undergone a massive scale-up in recent years. This is largely as a result of the Paris Climate Agreement, but also because new technologies have made it more possible for renewables to outshine fossil fuels.

In solar panel developments, for instance, research into capturing and using waste heat emitted by solar panels could help to reduce solar costs even more, while doubling the efficiency of solar cells. Photovoltaic tracking panels have also become increasingly popular, which use tracking systems to tilt and shift the angle of the panel as the day goes by to best match the sun’s position.

Wind turbines are much larger nowadays. One example is the 9.6 mega Watt (MW) turbine from Danish producer, MHI Vestas, that alone is able to power more than 8,000 homes. Power storage is increasingly possible, and many companies have partnered with battery producers to store extra power so it can be used on less windy days.

KEEPING TECHNOLOGY TURNING

As renewable resources grow in sophistication, it is vital that other systems also keep pace in order to effectively manage the power they create. 

For example, wind turbines are typically connected to the distribution network through step-up transformers. When energised by high inrush currents, these transformers can experience overvoltage on the distribution network. This can potentially damage equipment.

Overvoltage issues can be remedied by using technologies like pre-insertion resistors (PIRs). PIRs, such as those offered by Cressall, are a three-phase resistor with a high thermal mass that allows them to absorb energy from high inrushes, while still being compact enough to fit efficiently in a transformer substation. 

Resistor technologies can also help manage power in solar panels. One example is electric motors that help solar panels move to “track” the position of the sun. These motors can be fitted with braking resistors to ensure that the panels stop at the optimum angle when tracking the sun for maximum efficiency.

Braking resistors can also be used on wind turbines, particularly on fixed-speed winder generators where sudden changes in wind speed can have a detrimental impact on the stability of the system. By inserting a dynamic braking resistor in series with the generator circuit, designers can help the system to dissipate the excess power created by stronger winds, before it has chance to damage the entire system.

The UK’s current coal-free reign may not last forever — at least not yet — but the pause from burning fossil fuels certainly marks a brighter future. As renewable resources form an increasing part of our energy mix, it will be ever more essential to ensure that the technologies which power them, and those that manage the power, support the nation’s net zero goal.

For more information on Cressall’s resistor technologies for renewables, click here

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