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Floating wind farms for the future

FLOATING WIND FARMS FOR THE FUTURE

ARE FLOATING WIND TURBINES THE ANSWER TO RENEWABLE POWER?

Back in 2019, then-Prime Minister Boris Johnson promised 40 GW of UK offshore wind power by 2030. In early 2022, the Government raised that target to 50 GW, with an additional five GW from floating wind turbines. But are floating wind farms the solution to existing offshore power problems?

Many of us will be familiar with the sight of wind turbines. After all, there are more than 10,000 of the structures on land and at sea in the UK. In terms of efficiency, offshore wind turbines often have more favourable wind conditions, producing more electricity per turbine than their onshore counterparts.

But traditional offshore wind turbines have their limitations. Traditional offshore turbines are built onto a large steel column, fixed into a concrete foundation on the seabed. These can only be installed in relatively shallow waters, up to depths of around 60m. Not only does this limit the potential areas for turbine installations, it also means that the turbines have less access to the stronger winds that are often found further out to sea.

FLOATING FARMS

To capitalise on the stronger winds further out, floating wind turbines can be built instead. These are turbines built on huge floats, anchored to the seabed with weighted subsea cables.

Operating in much deeper water, floating wind farms make use of vast areas that were previously considered not suitable for offshore wind power. Being further out to sea also means that turbines can be a lot larger in size than their counterparts, producing even more electricity per turbine.

Kincardine, the world’s largest floating wind farm based in Scotland, has five operational floating wind turbines. Three cylindrical floats arranged in a triangular formation support each turbine, and pipes between the floats allow liquid ballast to be pumped around the structure. In this manner, the weight of the turbine can be shifted to stabilise it in harsh conditions, as well as orientating it for the wind direction.

Are we on track to meet solar power targets?

ARE WE ON TRACK TO MEET SOLAR POWER TARGETS?

MAXIMISING EFFICIENCIES TO MEET RENEWABLE TARGETS

In April 2023, a report published by the House of Commons stated that, at the UK’s current pace of change, it will miss its target of decarbonising the power sector by 2035. As the UK fights to secure its energy supply, what progress is being made in the renewable sector, and what needs to change? In this article, Simone Bruckner, managing director of resistor manufacturer Cressall, explores.

More and more applications are going electric. Whether it’s the cars we drive or the heat pumps in our homes, rising electrification is putting more pressure on the grid. In fact, the UK’s electricity demand is expected to double by 2035.

60 per cent of our current electricity usage comes from low-carbon sources, which includes renewables and nuclear power. But within the next twelve years, renewables are expected to supply up to 90 per cent of the country’s power if we’re to meet decarbonisation targets. In real terms, this sets a target of around 150 GW of renewable energy. But this is a long way off our current capacity of just 40 GW.

Further efforts to secure the UK’s energy independence while meeting decarbonisation targets have resulted in additional goals. The British Energy Security Strategy has outlined a 50 GW target for offshore wind by 2030, as well as a 70 GW target for solar by 2035.

But with a current solar capacity of just 14 GW, is the UK on track to meet such targets?

DELVING INTO SOLAR

One of the biggest issues faced by those in the solar sector is obtaining planning permissions and approvals. Industry body Solar Energy UK reported back in 2021 that around 17 GW of new projects were in the planning pipeline, with just under 800 MW of new projects entering the pipeline each month. But typically only around 500 MW of capacity is added each year, much lower than the approximate 4.5 GW required to meet the Security Strategy’s 70 GW target.

In Sleaford, Lincolnshire, a 600 MW solar farm able to power 190,000 homes is currently undergoing consultation with local residents. Despite being in talks now, if the plans for the farm are approved, it’s not expected to start construction until at least 2026.

Another problem with solar power is efficiency. Solar panels tend to operate with efficiencies between 15 and 20 per cent, compared to between 30 and 50 per cent for wind. Evidently, there’s improvements to be made to the efficiency of solar power if the UK is to hit its targets. But what can be done?

SAFE, EFFECTIVE MAINTENANCE

Maintenance is a key factor in improving efficiency. Regular cleaning and inspection ensures that the solar panels are working properly. But there might be times when the solar panel needs to be disconnected for more extensive maintenance or repairs, presenting an electrical safety challenge.

While there is still sufficient light, the solar panel will continue to produce electricity. This electricity must be discharged so that the panel can be handled safely. This can be done using a load bank, which dissipates excess electricity to allow safe disconnection, installation, and maintenance of solar panels.

THE BENEFITS OF MOTORISATION

Ground-mounted solar panels have the advantage of space, compared to those fixed onto rooftops. This means that the panels can be tilted and moved with respect to the sun’s position in the sky. An electric drive system is used to move the panels, either along a pre-programmed path or using information obtained via solar radiation sensors.

Moving the solar panels helps to maximise their efficiency throughout the day, as well as accounting for minute changes in the sun’s position and trajectory throughout the seasons. In fact, these systems can increase the output of solar farms by up to 35 per cent.

Motorising solar panels requires electronics that can ensure they move precisely and safely. To achieve this, a dynamic braking resistor (DBR) can be used. A DBR dissipates the excess voltage generated by the motors as they decelerate. As a result, the panels stop exactly when required, resulting in a more accurate positioning.

Though these slight changes in positioning may only be minute, when multiplied across an entire solar farm, they represent a significant proportion of its overall output and efficiency.

Finding suitable resistors for the solar sector can be a challenge. Cressall has vast experience in providing resistors for a variety of applications, including renewables. Offering resistors with no wearing components, they can last as long as the solar panels themselves, minimising downtime.

As deadlines get closer, pressure is mounting to provide a secure supply of green energy. Evidently, governments, planning regulators, energy companies and manufacturers will all have a part to play in the UK’s journey to green energy. As the House of Commons’ report states, the achievement of a decarbonised energy system will not come easily ─ but it is not impossible.

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Are EVs too heavy?

ARE EVS TOO HEAVY?

THE IMPORTANCE OF LIGHTWEIGHTING ELECTRIC VEHICLES

In June 2023, the Institution of Structural Engineers published a report suggesting that the weight of our cars is too much for many multi-storeys built in the 60s and 70s. Known for being heavier, EVs have been the first to be blamed ─ but is this fair?

It’s clear that cars have come a long way in design and development over the past 50 years. But while their safety, range, and ride have improved drastically, there’s something else that has increased too ─ their weight.

Looking at some of the most prevalent vehicles of the 60s and 70s highlights the increase in weight. The BMC AD016 was Britain’s best-selling car for more than five years and had a kerb weight of just over 830 kg. Other popular cars included the Ford Escort at 867 kg, and the estate Ford Cortina at 940 kg. So, what’s the comparison to modern vehicles?

CARS IN THE 2020s

Let’s consider last year’s most popular car ─ the Nissan Qashqai. Comparing petrol and equivalent hybrid models within the range, such as the Acenta Premium, shows a weight increase of approximately 250 kg with the partially electric version. The 1.3L petrol comes in at 1348 kg, versus the hybrid 1.5L version at 1612 kg. While the slightly larger engine will contribute to the weight increase, it’s clear that the battery itself ─ even for just a hybrid ─ adds up to the weight. And the Tesla Model Y, the UK’s best selling electric car, boasts a weight of 1980 kg, with 771 kg belonging to the battery alone.

But is it fair to place all the blame on electric cars? It’s worth noting that, while electric and hybrid equivalents are likely to be heavier, there are still plenty of larger petrol and diesel cars on the upper end of the scale. New Range Rovers typically weigh upwards of 2400 kg, and the trend towards larger vehicles in general is another important factor in the weight debate.

Therefore, making more lightweight vehicles is likely to become a growing priority ─ not just in achieving higher fuel efficiency, but also to support older and aging infrastructure.

BUILDING LIGHTER EVS

When it comes to electric vehicles, the battery is likely to be an area of focus. Simply opting for smaller batteries won’t do; this will only negatively impact the range of usability of the vehicle. Therefore, if we’re going to make EV batteries lighter, a more sophisticated approach is required.

One option is the implementation of regenerative braking technology. Regenerative braking allows the surplus energy generated by braking to be directed back into the battery. This improved efficiency can extend the EV’s range by ten to 15 per cent, and even higher in optimum conditions. Therefore, by implementing regenerative braking technology, it becomes possible to slightly reduce the size of the battery, without a huge effect on range.

To safely implement regenerative braking technology, a dynamic braking resistor (DBR) is essential. The DBR dissipates any excess energy in the system, such as that generated when the car is braking on a full battery. Providing a safe way of dispelling this excess energy is crucial to protect the electrical components in the vehicle and to prevent overvoltages.

In line with lightweighting measures, it’s therefore important to choose a compact DBR. Here at Cressall, we have a range of lightweight DBRs available. Our flagship EV2 resistor is just 15 per cent of the weight of an equivalent air-cooled resistor, making it an ideal choice for EV manufacturers seeking to cut vehicle weight with no loss to safety or performance.

While there’s truth in that EVs are typically heavier than their petrol equivalents, it’s clear that the trend towards larger cars in general has contributed to the strain being placed on our infrastructure. But with EV uptake only set to increase within the next few years, making them lighter must be a priority. Regenerative braking is just one example of a technology crucial to improving EV efficiency and weight ─ and with new technologies emerging all the time, it certainly won’t be the last.

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Overcoming EV regulatory challenges

OVERCOMING EV REGULATORY CHALLENGES

THE SOLUTION TO MEETING EU REGULATION WITHOUT IMPACTING PERFORMANCE

The end of the road for internal combustion engine vehicles (ICE) has been on the agenda for a few years now, with many countries on track to meet their own targets for final sale. But the rollout isn’t without its challenges. Here, Simone Bruckner, managing director of power resistor manufacturer for the electric vehicle (EV) market, Cressall, explains the resistor solution to ensuring EU-compliant braking systems.

According to the European Automobile Manufacturers’ Association, or AECA, of the 1.9 million cars registered in 2021, the number of diesel car registrations represented 66 per cent less than in 2017. In the same time period, battery and hybrid EVs experienced a tenfold increase. However, while electrification seems to be progressing well for cars, challenges remain in other vehicle categories.

THE REGULATION

EU regulation relates to any vehicle belonging to category M3 — vehicles used for the carriage of passengers, comprising of more than eight seats in addition to the driver’s seats with a maximum mass exceeding five tonnes. Typically, these are buses and coaches.

Regardless of how category M3 vehicles are fuelled, they must be fitted with a secondary or endurance brake to safeguard the vehicle’s ability to stop. Category M3 vehicles brake differently to cars, as they do not purely rely on their service brakes to slow down. Instead, they also use an endurance braking system, which enables the driver to reduce the speed, or descend at a nearly constant speed, without using its service brakes. The benefit of an endurance braking system is that it doesn’t overheat as quickly on long declines and reduces the risk of fade or failure of the service brakes.

In order to comply with regulation, vehicles must pass the ECE R13 Type -IIA test, which requires the vehicle to maintain a speed of 30 kilometres per hour (kph) for 12 minutes on a 7 per cent slope without using its service brakes.

THE CHALLENGE

In the past, passing this test has proven difficult for EVs. The technical issue comes when the battery is fully loaded. The vehicle’s endurance braking system works on a regenerative braking model, meaning that when the vehicle’s brakes are pressed, the kinetic energy is converted into electrical energy, which is directed to the EV’s battery to recharge it.

When an EV’s battery is full, the vehicle’s kinetic energy cannot be converted into electricity and stored, meaning regenerative braking is impossible, and the endurance braking system cannot operate. So in order to pass the test, it’s important to ensure the availability of sufficient capacity in the battery, or create a separate outlet channel for excess energy to be directed into to keep the system operational and ensure the vehicle can pass the downhill test.

THE SOLUTION

One solution to ensuring sufficient capacity of the EV’s battery is to fit a dynamic braking resistor that removes excess energy from the system and dissipates it as heat. This heat takes the form of hot water within the EV’s own, existing cooling system. Removing energy from the system in this way ensures that the endurance braking system remains active by providing an outlet for excess energy.

Typical concerns around the use of a resistor for this application centre around a possible negative impact on weight and cost. But Cressall’s EV2 water-cooled DBR is designed specifically for EV applications, providing the high reliability, mechanical simplicity and low weight required. The EV2’s unique patented design means it is typically ten per cent of the volume and 15 per cent of the weight of the inequivalent air-cooled DBR. It can also be integrated into a vehicle’s existing overall cooling system, removing the need for a separate cooling circuit, further reducing weight additions.

The shift away from ICE vehicles is well underway, and despite no solid targets for the end of the sale of ICE buses and coaches, their electric counterparts are proving popular in Europe, with sales expected to quadruple by 2030. But for uptake to have as much success as anticipated, it’s crucial for automakers to consider how to ensure their braking systems are compliant to keep the EU’s roads safe.

Category: NEWS