RENEWABLES Archives

Lessons from COP30

The critical role of grid stability in the energy transition

‘We can choose to lead, or be led to ruin,’ declared UN Secretary-General António Guterres, addressing delegates at COP30 in the rainforest city of Belém, Brazil. As the world pushes to triple renewable power capacity by 2030, attention is shifting from adding generation to preparing grids for the change. In light of COP30, Mike Torbitt, managing director of resistor manufacturer Cressall Resistors, examines the growing pressure on electricity networks and the role of grid stability technology as renewable deployment accelerates.

The world has recently seen record growth in renewable energy, with solar and wind forming the backbone of global decarbonisation efforts. Yet, despite that, COP30 delivered a clear message: the pace must quicken if we are to meet targets for 2030. Analysis from the Climate Action Tracker coalition, released at COP30, shows that “sticking to key climate pledges — tripling renewable energy, doubling energy efficiency and cutting methane emissions — could avoid nearly 1°C of global heating and significantly slow the rate of warming this century.”

Expanding renewable capacity at the pace needed to meet climate goals will demand unprecedented investment, infrastructure expansion and system upgrades. But increasing generation alone won’t be enough — the real challenge lies in ensuring that grids can handle the variable, fast-responding energy these new sources provide. Integrating that power reliably into networks that were not designed for variable energy sources is becoming the defining task of the energy transition.

The grid challenge behind rapid renewable growth

Renewable growth is radically changing the way in which electricity systems function. Solar and wind generation follow weather patterns, leading to steep rises and falls in generation that must be balanced in real time. As installations expand, these variations become more extreme, placing new stresses on equipment and system operators alike.

Today’s renewable output is constrained by congestion and capacity limits in transmission and distribution systems, limiting how efficiently the power is delivered to consumers. Storage capacity is expanding but remains far below what is required to balance supply and demand across all regions.

Without the right stability and protection technologies, high-renewable grids risk greater levels of curtailment, decreased asset lifetimes and reduced system reliability. As inverter-based generation becomes the dominant form of new capacity, networks are also losing the inherent stability once provided by conventional rotating machines. This shift makes grids more sensitive to faults, fluctuations and power disturbances, increasing the importance of technologies that can absorb, dissipate or smooth unexpected energy spikes.

Technology that makes high-renewable grids possible

This is where resistor technology becomes essential to keeping systems stable. Dynamic braking resistors (DBRs) offer a proven method for managing rapid changes in power flow, especially in systems where renewable output can increase or decrease quickly. By safely converting excess energy into heat, DBRs prevent over speeding in rotating equipment or instability in inverter-driven systems.

For wind turbines, DBRs are essential to managing sudden gusts or rapid changes in mechanical load. For solar, they support stability during cloud transients or fast inverter cycling and in storage and hybrid systems, they help maintain smooth operation during transitions or when switching between energy sources. At commissioning stage, DBRs also support system testing to ensure equipment performs safely before going live.

Cressall has decades of experience across renewable generation, grid infrastructure and transport applications, supplying DBRs engineered for long-term reliability, safety and demanding environmental conditions. As grids continue to evolve, this technology will continue to support the safe integration of new renewable capacity, especially in a future where inverter-based systems take on an increasingly large share of total generation.

What COP30 signals for the future

One of the key messages emerging from COP30 is that renewable growth must be matched by investment in modern, stable and flexible grids. The International Renewable Agency’s (IRENA) analysis reinforces this point, stating that “power system infrastructure and flexibility must expand at a much faster rate to accommodate rising shares of variable renewables”.

According to IRENA, at COP30 the Utilities for Net Zero Alliance (UNEZA) announced investment plans totalling over USD 1 trillion by 2030, with a significant emphasis on strengthening power grids and networks. This commitment from the world’s leading utilities demonstrates the scale of infrastructure transformation needed to support renewable expansion.

This has significant implications for grid operators, developers and technology suppliers. As renewables are installed more rapidly, system stress will rise and there will be greater need for proven solutions that ensure stability.

Digitalisation will play a growing role in improving forecasting and control, but physical safeguards such as DBRs will still be essential for protecting equipment and maintaining reliability.

COP30 reinforced the scale of work required to reach renewable and climate goals. But that transition cannot succeed unless grids can cope with the new realities created by variable, fast-responding, decentralised generation. Dynamic braking resistors offer a crucial layer of protection and stability, enabling renewable energy sources to be integrated in a secure and reliable way.

To find out more about the role of resistors in renewable energy generation, speak to Cressall’s experts

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The resistance to renewables

Why are energy providers abandoning net-zero strategies?

Oil and gas giant BP recently walked back the net-zero targets it introduced in 2020, saying the company had moved ‘too far, too fast’. The announcement is part of a worrying trend of energy providers and other multinationals reducing or watering down their sustainability strategies. Here, Mike Torbitt, managing director of Cressall, explores the causes behind this movement and explains the role that resistor technology can play in meeting sustainability targets.

In February 2025, BP announced plans to cut its budget for renewable projects by $5 billion, while simultaneously increasing its investment in fossil fuels to $10 billion per year.

The decision will see the oil giant produce 2.4 million barrels of oil per day by 2030. Given that just 36 fossil fuel companies are responsible for over half of the planet’s emissions, this step backwards has a hugely damaging potential.

But BP is not the only energy provider to backtrack on its sustainability commitments. The move comes a year after fellow oil giant Shell dialled back its 2030 target to cut net carbon intensity from 2016 levels, lowering its goal from 20 per cent to a range of 15 to 20 per cent. But why are energy providers turning their backs on these objectives?

Profit versus planet

Currently, renewable energy projects such as wind and solar are simply not returning as much profit for oil and gas companies as fossil fuels. According to 2023 figures from NPR, US companies producing oil and gas could expect to make a return of between 20 and 50 per cent return on investment on the capital invested into projects. For solar and wind projects, the estimated figure stands at just five to ten per cent.

Consequently, there is less investor interest in the stocks of oil companies that are diverting their budgets towards wind and solar. Take for example the five-year period between the end of 2019 and the end of 2024. New York Times data shows that BP’s stock prices fell by 19 per cent and Shell’s grew by around 15 per cent. Meanwhile, the stock price of competitor Exxon Mobil, which did not invest in wind and solar energy, grew by over 70 per cent.

There are a few major barriers to profitability. The first is that oil companies may lack the sector-specific experience required in order to succeed with wind and solar projects.

Exxon Mobil instead chose to invest in hydrogen and lithium extraction, since the skills needed are very similar to those used in extracting oil. While the mining of these elements comes with its own environmental concerns, both are vital components in the production of battery-powered vehicles.

A second factor affecting profitability is the high initial investment costs for renewable projects combined with the low prices of solar and wind power. This means that it takes years, or even decades, for investors to see return on investment.

Improving infrastructure

While these energy sources have become less expensive to generate in recent years, they tend to produce energy during the same time periods. For instance, on a particularly windy day, the wind energy produced will outstrip demand, which drives down prices. Additionally, wind turbines are increasingly being turned off as the grid is unable to cope with this surplus.

One solution to this issue is using interconnectors, high-voltage direct current (HVDC) cables that connect the energy grids of different countries, enabling the movement of renewable energy to international markets where demand is higher. HVDC technology is ideal for long-distance transmission with minimal energy losses.

In HVDC systems, resistor technology plays a vital safety role by dissipating excess wind energy during faults, helping to stabilise the grid and prevent damage. DC neutral earthing resistors also add a further layer of protection to HVDC converter transformers, both offshore and onshore, by managing fault currents and ensuring system reliability.

Ultimately, privately owned oil and gas companies are more likely to be driven by shareholder interests than they are by environmental targets. However, by ensuring that the correct infrastructure is in place to make the most from the renewable resources, it’s possible to improve both sustainability and profitability.

Looking for a reliable resistor partner for your HVDC project? Get in touch with our knowledgeable team.

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Keeping the UK’s most ambitious energy project afloat

KEEPING THE UK’S MOST AMBITIOUS ENERGY PROJECT AFLOAT

HOW RESISTORS ENSURE RELIABILITY IN TIDAL PROJECTS LIKE MERSEY TIDAL POWER

The UK’s clean energy transition is set to take a major leap forward with the Mersey Tidal Power project, a proposed development that could become one of the largest in the world. But what challenges does a project of this scale present for electrical infrastructure? This article explores how resistors can help stabilise the grid and extend component lifespan to ensure the long-term success of tidal projects.

The Mersey Tidal Power project is one of the UK’s most ambitious renewable energy projects to date. Inspired by successful tidal range developments such as La Rance in France and Sihwa Lake in South Korea, it aims to replicate the long-term viability of tidal power on an even larger scale. Using a barrage-style turbine array to harness the immense power of the river Mersey’s tides, the development could generate up to one gigawatt (GW) of clean energy. However, despite its promise, the scale and ambition of the project raises several challenges that require careful consideration.

STABILITY AND RELIABILITY DEMANDS

Unlike other renewable sources, tidal power generation follows a predictable pattern, being governed by the lunar cycle. However, tidal energy still experiences variations in output due to the changing intensity of tidal flows. Managing these fluctuations, particularly at such a scale, requires highly efficient electrical infrastructure.

Any variation in energy production needs to be carefully managed to prevent fluctuations from causing inefficiencies or disruptions in power transmission. Without this precise control, power surges or dips could destabilise the grid, undermining the reliability of the entire energy network.

The Mersey Tidal Power project’s sheer scale also introduces technical demands beyond standard renewable installations. With an expected operational lifespan of over 120 years, all components — especially electrical systems — must be designed to withstand extreme marine conditions. Saltwater corrosion and high mechanical stresses from strong tidal currents place exceptional demands on electrical equipment. Ensuring system longevity requires components that are not only resilient but also capable of maintaining performance over decades of operation.

ANCHORING TIDAL POWER

The success of large-scale tidal energy projects depends on a responsive and reliable electrical system. Dynamic braking resistors (DBRs) play a key role by absorbing excess energy during peak tidal flow. When tidal currents are at their strongest, turbines can generate more electricity than the grid can immediately use. DBRs convert this surplus electrical energy into heat, safely dissipating it to prevent voltage spikes or overloading transformers. By smoothing out power delivery, they help maintain a consistent and reliable supply of electricity, ensuring that tidal energy can integrate seamlessly with the wider grid.

Beyond grid stability, resistors also protect the physical infrastructure of the turbines. Rapid changes in water flow, such as shifts between ebb and flood tides, can create sudden torque variations on turbine blades and drive systems. DBRs help regulate these mechanical stresses by slowing the turbine’s rotational speed in a controlled manner, reducing wear on bearings, shafts and other moving parts.

Given the vital role that resistors play in tidal power generation, their durability in harsh seawater is essential. High-quality marine braking resistors are engineered to withstand the extreme conditions of tidal power systems, including corrosion, heat and mechanical wear. Designs often incorporate sheathed mineral-insulated elements to protect against physical damage and environmental degradation, alongside marine-grade stainless steel to resist saltwater corrosion. These durable materials allow resistors to maintain peak performance for decades, even in the demanding conditions of tidal power projects.

While the scale of the Mersey Tidal Power project raises technical challenges, the proposed development is a bold testament to the UK’s commitment to clean energy. As the government increasingly supports tidal power as part of its long-term energy strategy, this project could pave the way for widespread adoption of tidal infrastructure. Throughout this transition, resistor technologies are expected to play an important role in ensuring the stability of the grid and the longevity of power generation systems.

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Protecting the backbone of clean energy

Protection technology ensures safe, reliable battery storage for renewables

In the UK, the share of electricity generation from renewable sources during the second quarter of 2025 reached a new record level of 54.5 per cent of all generation, according to the Department for Energy Security and Net Zero. But as we shift closer to a net-zero energy system, it becomes critical to have a robust storage solution to harness the energy we produce. Here, Mike Torbitt, managing director of Cressall, explores the technology behind battery energy storage systems (BESS).

The Government’s Clean Power 2030 Action Plan, introduced in December 2024, looks to ensure that clean sources produce “at least as much power as Great Britain consumes in total” and “at least 95 per cent of Great Britain’s generation”. Achieving this will rely on a blend of offshore wind and solar energy deployed at scale.

But this transformation hinges on flexibility. As wind and solar dominate, BESS is becoming the backbone of grid stability, absorbing excess renewable energy and releasing it during demand peaks. Lithium-ion technology leads the way here, comprising 95 per cent of UK BESS projects, thanks to its rapid response and scalability.

The BESS landscape

Higher renewable penetration has driven demand for energy storage. As of September 2025, RenewableUK reports 1,943 active battery storage projects in the UK, with 6.8 gigawatts (GW) of operational capacity — a 509 per cent increase since 2020.

Even larger projects are underway. Tillbridge Solar in Lincolnshire will deliver 1.5 GW of solar PV and three GWh of BESS, while Pembroke Battery in Wales will become the UK’s largest storage facility when construction begins in early 2026.

These assets will provide fast frequency response, peak shaving and renewable firming. Their success, however, depends on safe, reliable integration into medium-voltage (MV) grids. Systems typically connect at 6–36 kV, where grid code compliance, fault studies and earthing design are critical. Without robust protection, the promise of storage could falter under grid physics.

MV challenges

MV grids are faultenergy rich environments. In solidly earthed MV systems, a singlelinetoground fault can drive very high currents, imposing severe thermal and mechanical stress on stepup transformers, converter valves and switchgear.

For BESS, rapid dispatch and high-power flows amplify risks such as inrush currents, transient overvoltages and earth faults escalating in milliseconds, posing compliance and protection challenges under the GB Grid Code. Without controlled earthing, fault magnitudes can exceed clearing times and equipment limits, risking outages and costly repairs.

As grids add high voltage direct current (HVDC) links to ferry offshore wind and remote solar, and as BESS ties into converter stations or MV collectors, abnormal conditions like DC faults reflected into AC neutrals demand predictable neutral behaviour. Limiting ground fault current is essential to maintain converter transformer integrity and prevent cascading trips.

Making BESS safe

This is where neutral earthing resistors (NERs) do the quiet, but crucial work. By inserting a defined resistance between the transformer neutral and earth, an NER limits earth fault current to a level that protection relays can detect and clear selectively, without tripping the entire plant.

NERs prevent transformer insulation damage, reduce arc flash hazards, minimise voltage stress on equipment, enable controlled fault detection and isolation and maintain system stability during fault conditions. Cressall supplies NERs tailored for MV and HV duty in renewables and storage, with engineering guidance that highlights how DC and AC NERs protect converter transformers and maintain system integrity during abnormal events — requirements that map directly to MVconnected BESS.

Every Cressall NER is designed to IEC and IEEE standards, factory tested under fault current conditions and built with stainless steel elements for outdoor durability. They are rated for continuous operation in harsh environments, ensuring reliability in demanding renewable installations.

In practice, this means fewer catastrophic stresses on transformer windings and converter components, better adherence to grid code protection settings and smoother interconnection approvals.

The UK is reshaping its energy system, but success depends on more than megawatt-hours. Behind every project is a layer of protection technology that keeps the grid stable. As the UK races toward Clean Power 2030, NERs are foundational, turning unpredictable faults into manageable events, making MV-connected BESS bankable and resilient.

To learn more about Cressall’s NERs for BESS applications, please visit the website

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