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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Futureproofing tidal power

FURURE PROOFING TIDAL POWER

HOW TECHNOLOGY CAN HELP TIDAL POWER TO REALISE ITS POTENTIAL

The UK Government estimates that tidal energy could meet around 20 per cent of the country’s electricity demands. Considering the UK is an island and entirely surrounded by water, this comes as no surprise. Despite this fortunate position, uptake of tidal power has been slow. How should we encourage the development of this promising resource?

Tidal power functions in a similar way to wind power. Tidal turbines are placed underwater where the change in tide from high to low and low to high turns the blades to produce electricity. Tidal power is more reliable than solar or wind because we can easily predict the movement of the tides, which is determined by the Moon.

However, tidal power comes with extremely high upfront costs. To make the resource more feasible, its technology needs to deliver a high performance, allowing this cost to be recovered more quickly and making tidal power more appealing.

BIOFOULING PROTECTION

Biofouling occurs when plants and animals attach themselves to underwater constructions as often seen on the hulls of ships. However, biofouling also alters the hydrodynamics of submerged tidal turbines, presenting a productivity problem.

The biofouling organisms attach themselves to the surface of turbine blades making them rougher, which increases losses due to friction and therefore reduces the efficiency of the turbine. This, in turn, will lower tidal power’s performance and make it less cost-efficient.

Antifouling methods, such as a non-toxic coating with a low friction, can prevent organisms from attaching to surfaces whilst avoiding damage to surrounding marine life. These coatings are currently used in the shipping industry, but we must explore their applications in tidal power to reduce maintenance costs and improve efficiency.

CALMING THE STORM

Protecting submerged turbines from their marine co-habitants isn’t the only step tidal power plants should take. Sudden changes in water flow can be equally challenging for tidal turbines. Although the time between high and low tide is consistent, the distance between them, known as tidal range, is not. The tides are determined by the Moon and the Sun, and in some circumstances, extreme tidal forces such as spring tides can occur.

Tidal turbines need to be able to cope with these forces, as well as any unexpected and extreme weather conditions. By placing a dynamic braking resistor (DBR) in the generation and control circuit, can protect against any excess power generated by strong currents can be safely dissipated. The turbine system will therefore be less prone to damage, increasing its performance capacity and decreasing the chance of regular repairs.

The use of Cressall’s EV2 advanced, water-cooled resistor, which is suitable for low and medium voltage applications. The range is modular, so multiple resistors can be combined to handle power outputs up to one Megawatt. The EV2 also boasts an IP56 ingress protection rating, making it able to withstand harsh marine environments and suitable for the tidal turbine application.

BLADE DEVELOPMENT

Location also plays a major role in tidal electricity generation, with generator requirements including the need for a flow speed greater than two metres per second. Locations that can offer this are limited, which is one of the reasons for tidal power’s slow uptake. In the UK, only the north coast consistently meets this requirement.

Turbine blades with a high tip-speed ratio are slimmer and produce less drag. With less drag, the turbines can achieve a larger number of rotations at a lower speed. Through the development of blades that can operate at lower flow speeds, the number of sites at which tidal power can operate can increase, making it a more viable option.

Expensive installation costs cannot be avoided when increasing tidal power. However, by investing in technological developments that ensure less maintenance, higher efficiency and increased site suitability, tidal power can realise its potential and increase the prevalence of renewables globally.

For more information on Cressall’s tidal resistor technologies click here

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A transcontinental renewable network?

A TRANSCONTINENTAL RENEWABLE NETWORK?

HOW HIGH VOLTAGE DIRECT CURRENT TRANSMISSION COULD TRANSFORM POWER SUPPLY

The SuperSmart Grid (SSG) is a theoretical concept that involves the creation of a transcontinental electricity network connecting Europe, the Middle East and North Africa to deliver low cost, high capacity, low loss electricity. To support global efforts to decarbonise power generation, could the SSG become a reality?

The SSG is a fusion of a super grid, a wide-area, often transcontinental transmission network and a smart grid, which uses digital technology, such as smart meters, to react to fluctuations in energy demand.

By implementing this system across Europe, the Middle East and Africa, this geographical area could benefit from an entirely renewable energy supply, which in turn supports the United Nations’ Sustainable Development Goal Seven: ensure access to affordable, reliable, sustainable and modern energy for all.

Offshore wind farms and solar power are the two resources that offer great potential, given the large number of suitable sites for both systems throughout the region. Having identified potential energy resources, how can this energy be transmitted to meet demand over such a vast area?

DEVIATING FROM THE AC NORM

High voltage direct current (HVDC) uses direct current (DC) for most electrical power transmission. Although DC is less common than standard alternating current (AC) systems, it meets the demands of the SSG for a variety of reasons.

HVDC transmission is a proven method of achieving power transmission over very long distances. It would play a vital part of the SSG, since it allows power to be transmitted from areas where it is in abundance to areas experiencing a shortage, which would secure the energy supply across the entire region. It would also facilitate the use of offshore wind farms — whose natural location is so distant from areas of electricity demand that HVDC is essential to ensuring efficient transmission.

HVDC also allows power transmission between unsynchronised AC distribution systems. AC systems operate at a set frequency and if these frequencies are different, the systems cannot be connected. HVDC circuits do not have a frequency, eliminating this problem and allowing multiple circuits to be interconnected.

Most significantly, HVDC suffers lower electrical losses than AC transmission. It has a uniform current density throughout the line, so there is no skin effect as there is in AC circuits. Although the corona effect, which is an electrical discharge that appears around a charged conductor, is still generated in a HVDC system, it is considerably lower than in AC systems, facilitating more efficient electricity transmission across the vast area encompassed by the SuperSmart Grid.

CONVERTING BACK TO AC

HVDC is ideal for transmitting over long distances, but when transmitting electricity into the local AC transmission grid, the direct current must be switched back to alternating current using a converter system. All converters, including HVDC converters, generate harmonic distortion to some degree.

If harmonics are not controlled, they can wreak havoc with the transmission system, jeopardising power quality and increasing the chances of equipment malfunction and electrical losses on the line. Therefore, it is important to integrate harmonic filters into the HVDC converter stations to block these unwanted currents.

Harmonic filters allow current at the frequency of the AC network to pass through, while redirecting distorted harmonic currents into a harmonic filter resistor, where they are dissipated as heat. This ensures that the unwanted currents are safely removed from the transmission network in a controlled way, which helps to secure the power supply when converting from DC to AC.

Although the SuperSmart Grid is purely theoretical, it’s clear that the technology necessary to realise this concept already exists. With countries all over the region setting ambitious renewable energy targets, perhaps this could be the solution to providing a secure, sustainable power source across all three continents.

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