Repowering wind farms with new upgrades will extend the life of the turbines and generate more reliable wind power.


We plan for retirement, but what about our wind farms?

The use of wind power has changed from windmills in centuries past to high tech wind turbines today. Remarkable advances in wind turbine technology and design over the last three decades means that solar and wind are now the lowest cost form of new generation in Australia.

Wind power is a plentiful, efficient and clean energy source. The Clean Energy Council reported that in 2019, Australia's wind farms produced 35 per cent of the country’s clean energy. More than 830 megawatt hours of wind energy were installed in the same year, the most in any year of wind farm developments.

Australia’s wind energy sector in 2019

Australia’s wind energy sector in 2019

Source: Clean Energy Council, 2019

Technology approaches retirement age

While new wind farms are going up, the first generation of large-scale wind turbines are nearly ready to come down. Their design lifespan was usually 20 years but, their operating life can be up to 25, or even 30, years depending on individual site conditions. The electrical balance of plant often has a design life of more than 25 years.

Consequently, owners and operators of first-generation wind farms must now decide what’s best for their ageing structures, decommissioning, repowering or extending their life. Operators must find the balance between community expectations, landowner requirements, planning permits, financial returns, opportunity costs, environmental factors and equipment operating life in their decision-making.

End of life decision-making considerations

The retirement of ageing wind farm technology is uncharted territory, for limited examples of end-of-life experiences.

In some ways, the retirement of ageing wind farm technology is uncharted territory, as there are limited examples of end-of-life experiences.

What is end-of-life?

As wind turbines near the end of their operational life, they are not capable of generating as much power because they require greater maintenance, hence increased downtime and repair costs. However, the assets may be technically capable of operating for longer if their capability is extended.

Generally, in Australia it’s the responsibility of the owner to decommission the site, as Development Approvals contain clauses explicitly setting out the expectations around decommissioning and rehabilitating the site.

By watching the process of decommissioning first-generation wind farms internationally, lessons learned can be applied to Australian sites, reducing operation and maintenance is critical, as is streamlining asset management.

A note on repowering

Repowering an existing wind farm (replacing old turbines with newer, more powerful models) is a popular choice for onshore wind farms. Many of the early sites that were developed in Australia are still some of the best sites in the country in terms of wind resource and grid access.

While Australia has many potential sites for wind farms, actually finding sites with good grid access is becoming difficult. This can make repowering an attractive option. Also, communities who have lived alongside wind farms may be more supportive than communities for whom wind farms are a new development.

We now focus on the factors that inform lifetime extension of existing wind turbines and balance of plant as they near retirement age.

Technical assessments informing lifetime extension

It’s a long-held perception that interest in lifetime extension increases in countries where conditions for new wind farms are unfavourable. Nevertheless, with more advanced technical and digital analysis assessments available to wind farm owners, a new perspective is coming to the fore return on investment might still be achievable in countries where new wind farms are just as favourable as lifetime extension.

Aurecon works with clients to create models based on historical operating data of specific wind farms and expected future performance to inform decisions around lifetime extension for Australian wind farms.

However, one barrier is the lack of in-depth digital data on wind farm equipment more than 15 years old. In the future, more detailed digital data on turbine performance will exist, but the lifetime-extension calculations of first-generation wind farms are much more limited.

Embracing the rise in digitisation

There is potential to use a data-driven approach to inform lifetime extension assessments through the creation of a digital twin of assets. Although relatively new to the wind industry, this is a responsive system that connects physical infrastructure to a digital environment with a digital model of assets.

It provides enormous benefit to undertake real-time scenario assessments in a replica world, devoid of risk, while being dimensionally accurate.

Digital scenario planning helps to better understand operational constraints, asset performance and maintenance requirements.

A related digital evolution is the move toward digital threads. A digital thread unifies digital records about an asset across functions that traditionally have been siloed, from the earliest steps in product definition, all the way through to asset management.

Asset management strategies

We need to be developing thorough and sophisticated asset management strategies that fully embrace the later stages of a wind farm’s life – not only the earlier stages in which operations and maintenance may have been conducted under contract with risks managed very effectively.

Any wind farm’s extension of life will need to be achieved through effective operations and maintenance and refurbishment. Owners, and even wind turbine suppliers, are beginning to think in more sophisticated ways about whole-of-life asset management strategies that maximise project value for the longer term.

Thorough due diligence and realistic assumptions in this area will be vital for developing viable business cases across an increasing range of possible lifespans.

Good asset management practices and leveraging operating data

Good asset management practices and leveraging operating data

Good asset management practices and leveraging operating data

Risk factors when considering lifetime extension

A key consideration for wind farms reaching their end-of-life is how far the assets can be extended. At times the decision is easy, and the options are straightforward.

For the majority, however, it is very complex and there are many environmental, social, technical and financial elements to consider. Part of any technical engineering assessment is the consideration of risk factors:

  • The performance of the life extended machine, in terms of megawatts generated and limited by availability
  • If there’s missing data on loading and fatigue because the product information is unavailable
  • The lack of international standardisation of methodologies for lifetime extension assessment
  • Whether the landowner agreements allow for extended operation
  • Whether the planning permit allows for extended operation and any requirements around decommissioning of turbines as they cease to be financially viable to operate

Financial decision-making factors

Any decision to extend the operation of a wind farm needs to be supported by a cost/benefit analysis.

  • How much is it going to cost?
  • What is the level of uncertainty around how long it can be extended?
  • How does the cost compare with decommissioning, re-permitting and repowering?

In addition, new wind technology has dwarfed the first-generation wind farms in both size and capacity. Consequently, part of the end-of-life calculations is the opportunity cost of the difference in wind power generation if new equipment and infrastructure is installed against the benefits of extending the life of the existing wind turbines.

The digital twin referred to earlier could be used along with an electricity market model as part of a two-sided digital platform. This platform would allow supply and demand to be assessed seamlessly with the unit of value for a wind farm being a ‘life extension action’.

Such an action is considered in two parts: a description of the possible action and a computationally-derived life prediction associated with executing the action. The prediction states that if the action is taken, then a specific turbine, operating under specific conditions, will have its life extended by a specific, calculated amount of time, at a calculated cost balance.

Once that value is clear, the operator can make a financial lifecycle decision on their assets.

The sustainability of end-of-life

As the first and second (and beyond) generation wind turbines and balance of plant near retirement age, there is a whole industry that needs to develop around it to recycle and reuse waste. Despite a great deal of research and development in this area, it isn’t industry mainstream yet, but it’s not the only industry facing composite recycling issues.

European predictions of composite waste per sector

European predictions of composite waste per sector

European predictions of composite waste per sector

Source: European Technology & Innovation Platform on Wind Energy, September 2019

The European Union recently supported research into composite recycling for the wind energy industry due to its growing issue. Countries should develop a local capability to recycle wind turbine components in line with community expectations that equipment producing clean and green electricity should also end their life in the same way.

Shaping the future

Wind energy is being harvested across the world and Australia is one of 29 countries that has more than 1 000 megawatts installed. It’s a sector that continues to grow and advance in terms of technology, energy capture and transmission.

There are enormous, unceasing benefits of wind power as a renewable and endless supply. It provides a vital service to power our homes and businesses, stabilise the grid and contribute to an overall reliable supply of electricity.

That’s why, as a country, we should continue to embrace the future of wind power with support and investment. Getting the lifetime extension or repowering approach of wind farms right is an important part. If we do, we will see a sustainable and economically-viable wind energy sector that powers our world for decades to come.

About the Author

Katrina Swalwell is former Technical Director in Aurecon’s energy business. She is a senior wind engineer who is committed to an economically and environmentally sustainable renewable energy future. Katrina has significant experience leading cross-disciplinary teams to contribute to tangible improvements in Australia’s traditional and renewable energy market.

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