Category: RENEWABLES

PREPARING FOR CHANGE

RESISTORS HELP TO GET THE MOST OUT OF WIND POWER

In January 2025, the UK government announced new measures to unlock up to thirteen major wind projects as part of its Plan for Change. But with wind curtailment — the switching off of wind turbines — reaching record levels in 2024, how can we make the most of the energy generated? Here, Mike Torbitt, managing director of Cressall, explores the role that resistors can play in preventing the wastage of wind power.

The government’s Plan for Change aims to modernise the ‘outdated and archaic’ infrastructure regulations to increase the pace at which offshore wind projects are constructed. In total, the measures could generate up to 16 Gigawatts (GW) of electricity and around £20-30 billion of clean energy investment.

The announcement is promising, but much of the newly harnessed wind power could be wasted. Turbines are frequently turned off in periods of high wind, to protect the grid system from being overwhelmed by the power generated.

According to a report from electricity supplier Octopus, enough energy was wasted in the first nine months of 2024 to power two million UK homes for a year. Not only does wind curtailment limit the UK’s ability to fully transition to clean energy, but it also results in higher bills for consumers.

And the problem is growing — the costs of wind curtailment will reach £3.7 billion by 2030. As the UK continues to invest in wind power, it’s important that additional energy generated is put to good use. So, why is energy being wasted and how can this be prevented?

DISTANCE ISSUES

The key reason for switching off wind turbines is distance — both from the grid and from demand.

Offshore farms are much further from the grid than their onshore counterparts, meaning there are less readily available connection points to distribute power to the transmission network. Consequently, in the case of strong winds, there are fewer options available to distribute the energy elsewhere.

The remote location of offshore windfarms also means they are located far from high-demand areas. For example, Scotland currently has seven operational offshore windfarms, many of which are located near the north of the country where population density is low. Demand for energy is greater elsewhere, but inefficient cable networks mean that a lot of power is lost during transmission.

HANDLING THE EXCESS

Energy experts have several suggestions on how to tackle wind curtailment. For instance, the Octopus report recommends zonal pricing, which means that people living near turbines can benefit from cheaper energy rather than it going to waste. The research suggests that businesses could save in the region of 65 to 99 per cent on energy costs by moving to Scotland and benefitting from zonal pricing. While the prospect of lower bills would hopefully encourage people to welcome the development of renewable energy projects within their communities, moving to energy-abundant areas isn’t feasible for all businesses.

Another way to minimise wastage is by improving the infrastructure that transmits energy from offshore sites to high-demand areas. In March 2025, construction will begin on the Eastern Green Link 1 (EGL1), which will enable the transmission of energy from Torness in Scotland to Hawthorn Pit in the North East of England. Once complete, the high-voltage direct current (HVDC) project will deliver enough electricity for two million homes.

HVDC enables efficient power transmission over long distances between offshore wind farms and the grid, thanks to its consistent current density. Resistor technology is essential in HVDC systems, safeguarding against grid failures by absorbing excess wind energy until the transfer is safely halted. Additionally, DC neutral earthing resistors provide further protection to the system, both onshore and offshore, within HVDC converter transformers.

Cressall has extensive experience in supplying resistors for renewable projects, including a GE Vernova partnership covering five HVDC projects in the North Sea.

The government’s aim to amend inflexible planning restrictions and boost wind power generation projects through its Plan for Change initiative is a welcome development. However, to create real change, the rollout of energy transmission projects must keep pace with offshore wind developments. HVDC systems supported with reliable resistor technology will enable the UK to reduce wind curtailment and make the most of the renewable resources available.

Contact a member of the Cressall team for advice on selecting the right resistors for your renewable project.

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ENABLING GREAT BRITISH ENERGY

A ZERO-CARBON GRID REQUIRES SPECIFIC TECHNOLOGIES TO ENSURE RELIABILITY

As part of Labour’s plan to boost the UK’s renewable energy production, ‘Great British Energy’ will see the production of a greater number of floating offshore wind farms and tidal power projects. However, for these technologies to be a success, it’s essential to have the right enabling mechanisms in place. Here, Mike Torbitt, Cressall’s managing director, explains the role of resistor technology in making GB Energy a success.

While the exact details about what GB Energy will involve are still uncertain, we can paint a pretty good picture of it from the current information at hand. Starmer’s government intends to invest £8.3 billion of funding into a new, publicly owned green power company as part of wider energy security and sustainability goals.

DELVING INTO GB ENERGY

GB Energy will work with the private sector to provide investment into emerging energy technologies like green hydrogen, floating offshore windfarms and tidal power. It will also scale investment into existing renewable technologies like onshore wind and solar power.

By boosting the UK’s renewable energy power, GB Energy is projected to create 650,000 new jobs across the UK, lower energy bills, increase energy security and create a zero-carbon energy system to the UK by 2030. Labour has pledged to establish GB Energy within its first few months of parliament by passing a new Energy Independence Act, meaning we could see GB Energy materialise by the end of the year.

While the benefits of transitioning to a 100 per cent zero-carbon energy system are abundantly clear, there are certain logistical and technological considerations to make to eliminate fossil fuels from the energy system completely.

THE CHALLENGES OF RENEWABLES

Whether it’s energy from the Sun, sea or wind, renewables have one thing in common — their input energy is extremely variable. For tidal and wind projects, the turbines work in a very similar way, so manufacturers must ensure they can safely manage what can often be high and unpredictable surges of power.

There may be times where winds or waves are so strong that high inrush currents occur. These can result in overvoltages in the system, leading to component damage, or even failure in extreme cases. When renewables like these make up the entire energy system, preventing component failure from scenarios that we know will occur at some point is essential to continuity of supply.

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

GETTING IN CONTROL

Overvoltage issues can be remedied by using resistor technologies, which all work by limiting or regulating the flow of electronic current in a circuit. Depending on the specific renewable application, there are different solutions to prevent overvoltages.

For tidal turbines, a dynamic braking resistor (DBR) can be integrated into the generation and control circuit to protect against any excess power generated by strong currents. Cressall’s EV2 advanced, water-cooled resistor is designed for these 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 tidal turbine applications.

In wind turbines, overvoltages are avoided by using a pre-insertion resistor (PIR). Insulated for the full system voltage, PIRs like Cressall’s mitigate against temporary overvoltages, such as those caused by exceptionally strong winds. They also absorb and control transient magnetising currents within transformers throughout the network. This control helps keep voltages consistent with minimal dips, reducing potential disturbances for users of the power network.

While the specifics of GB Energy are still yet to be announced, a fully renewable energy grid is certainly on the cards in the coming years. The industry will need to consider the importance of having the right technology in place to deal with the challenges that renewables bring, and make green energy a viable system nationwide.

CRE660/08/24