Professor Christopher Vogel , from the Department of Engineering Science, sets the record straight on the science and economics of wind turbines, and why these must be a key component of the UK's net zero energy strategy.
Professor Christopher Vogel.Few energy technologies divide public opinion quite like wind turbines. To some, they are elegant icons of the green transition, whilst others proclaim them to be monstrous eyesores that ruin the landscape . Whether you love them or hate them, one thing is clear: if the UK is to meet its net zero target by 2050 , then wind power will have to play a dominant role in getting us there. Policy makers have signalled their commitment, having recently approved one of the largest wind farms in the world to be built in Scotland. Yet frequent misinformation and local protests reveal that many remain to be convinced of the benefits of wind power.
So how do wind turbines actually work? How efficient are they? And how large a role will they realistically play in a carbon-free future?
How wind turbines work, and how efficient they really are
Wind turbines convert the kinetic energy of moving air into mechanical energy, which is then transformed into electricity by a generator. These are not modest structures: the latest offshore models are the largest rotating machines ever built, with rotor diameters exceeding 200 metres and towers taller than most skyscrapers. A single turbine today can generate enough electricity to power 15,000 to 20,000 homes.
Offshore wind is particularly well suited to UK conditions, with the North Sea providing both ample winds and relatively shallow waters. This gives the UK and other North Sea countries one of the best renewable resources in the world.
There is a physical limit to how much energy a turbine can extract from the wind (known as the Betz Limit), which peaks at around 59.3%. Encouragingly, modern offshore turbines operate fairly close to this theoretical maximum. But a wind turbine's effectiveness also depends on the "capacity factor": the proportion of time a turbine produces electricity at full output. We all know that the wind doesn't blow all the time. Yet North Sea areas generally have strong and consistent wind speeds, meaning that the capacity factor of UK offshore turbines averages just over 40% . For UK onshore wind turbines, the figure is lower, around 26%, but this is still favourable compared with solar power.
With solar photovoltaics, the conversion efficiency (the proportion of sunlight converted into electricity) is typically around 15 -20%. But the capacity factor, which reflects how much electricity is actually produced over time, is significantly lower , averaging around 10-12% in the UK due to cloud cover, seasonal variation, and the day-night cycle.
The energy payback period is another important consideration. Most UK wind turbines recoup the energy used in their manufacture, transport, and installation within 12 to 24 months, and they can generate electricity typically for 20 to 25 years. From an energy efficiency and sustainability perspective, the numbers are compelling.
The role of wind turbines in the UK's net zero future
The UK's transformation over the past 15 years has been remarkable. In 2010, around 75% of electricity was generated from fossil fuels. In 2024, coal had almost entirely disappeared from the mix, with wind being the largest single source of power , contributing roughly 30% to the national grid, more than natural gas at 26%.
Offshore wind is particularly well suited to UK conditions, with the North Sea providing both ample winds and relatively shallow waters that simplify installation. This gives the UK and other North Sea countries one of the best renewable resources in the world. In Denmark, 56% of their energy came from wind power in 2024 .
The stark reality is that we will need many more Berwick Bank-sized windfarms if we are to realistically meet our targets.
The newly-approved Berwick Bank offshore wind farm on Scotland's East Coast demonstrates the UK Government's commitment to expanding our wind power capacity. Once fully operational, this 300 plus-turbine windfarm would generate up to 4.1GW, enough to power more than six million homes. But despite its colossal size, the stark reality is that we will need many more Berwick Bank-sized windfarms if we are to realistically meet our targets. The UK Government aims for us to generate 43-50 GW of power from offshore wind by 2030 , and potentially up to 125 GW by 2050 .
Installing so many turbines at high density will see us moving from "wind farms" to "wind powerplants." Many of the wider impacts of this shift are currently unclear. A focus of my fluid mechanics research in Oxford is understanding how these turbines would interact with each other within large farms, how the large farms affect each other, and their interactions with the wind and the atmosphere, to more accurately predict how much energy they would produce.
What about the drawbacks?
No energy technology is without its challenges, and wind power is no exception. Addressing the variability issue will require a complete overhaul of the National Grid, particularly building enough energy storage capacity - likely not just batteries - to keep the lights on when the wind isn't blowing. Another key issue is the maintenance and decommissioning of wind turbines. These are large, complex machines, especially offshore wind turbines, which also have to contend with the harsh marine environment. However, advances in drone-based monitoring, sensor technology, and predictive maintenance are improving reliability and reducing costs.
Addressing the variability issue will require a complete overhaul of the National Grid, particularly building enough energy storage capacity to keep the lights on when the wind isn't blowing.
At end-of-life, around 85-90% of a turbine's mass , including steel towers, copper wiring, and concrete foundations, can already be recycled using standard processes. The main challenge lies in the blades, often made from glass fibre or composite resin, which are difficult to break down. Up to now, these have typically been incinerated or landfilled. But the sector is already exploring innovative alternatives, for instance, turning the blade materials into a component of cement, or replacing them with recyclable substitutes.
Ultimately, the challenge of building a circular wind economy offers the UK a brilliant opportunity to drive growth and create a new generation of skilled jobs in green energy, advanced materials, and engineering.
The road ahead
Wind power is already delivering substantial economic, environmental, and energy security benefits to the UK. But for this to continue, a stable and supportive policy framework needs to be in place to give developers the confidence to plan, finance, and deliver projects at scale.
The challenge of building a circular wind economy offers the UK a brilliant opportunity to drive growth and create a new generation of skilled jobs in green energy, advanced materials, and engineering.
The UK's Contracts for Difference (CfD) scheme has been a major success in driving down costs of both on- and offshore wind. But more is needed. In particular, policy makers must accelerate grid infrastructure upgrades to connect turbines to demand centres, invest in port facilities and manufacturing capacity, and clarify planning rules. This needs to be combined with investment in the skills workforce of tomorrow, for instance apprenticeships in turbine maintenance.
Realising the full potential of wind energy for the UK is a highly multi-disciplinary challenge encompassing engineering, atmospheric physics, and economics, to name just a few areas. The UK has strong potential in wind energy and it is great to see projects like Berwick Bank go ahead, but it is important that this momentum is sustained to achieve the country's net zero goals.
