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How integrated thinking can help boost the energy transition

April 04, 2024

By Tom Pendrey

How can we think more holistically about our renewable energy sources to better leverage the technology at our disposal?

The UK’s demand for electricity is set to rapidly increase. It will significantly reduce the margin of supply available from dispatchable sources.

We need to work quickly to upgrade the grid and bring new sources of generation onto the system to make up the shortfall. But we also need to rethink the way we use renewables. That is key to helping meet the demand for dispatchable power and address the energy transition.

To adapt at a sufficient scale and pace, we need to make the most of the systems we already have at our disposal. This can’t happen with isolated thinking or approaches. As with most things, combining resources while harnessing the right benefits at the right time makes things easier and more efficient. This is the thinking behind Stantec’s ‘Dispatchable Integrated Generating Systems’ model—or DIGS.

How can we leverage and combine renewable power to ease the energy transition? 

DIGS is a new, process-driven method of merging multiple renewable energy sources like wind, solar, hydropower, and battery energy storage systems. Then we leverage their collective benefits and maximise their potential for the energy transition.

We’re examining how this method, if rolled out on a national scale, can boost efficiency and returns for energy operators.

So how does it work?

It starts with a system that combines energy from a wind or solar farm with a small battery energy storage system as well as a hydropower station. Next, the DIGS model uses innovative control logic to work out how much energy each source is generating. And it does it on a real-time basis.

The goal is to prevent wastage of stored energy. So, when weather conditions are right and baseline operating requirements are met, the model will always prioritise the dispatch of energy generated from the wind or solar systems. It basically ‘saves’ the energy in the hydro plant. 

This process conserves more water than in a traditional setup. We can use that saved water to meet demand during peak times and offer high-value power to the grid.

As the DIGS model also includes a small battery energy storage system. When needed, the system can provide fast-frequency response. This helps balance the supply and demand of electricity and improves the reliability of the power system. It helps promote energy security by having electricity always available when needed, regardless of the conditions outside.

All of this should improve real-time dispatch decisions for operators and prevent the wasting of energy. By being more informed, operators can save more water in hydropower reservoirs. It also allows them to provide more ancillary services, such as rapid responses to changing grid demands; have more control over frequency and voltage levels; and increase their revenue.

We can capture these benefits at a cost far lower than a system dependent on wind power and battery energy storage systems alone.

By using the DIGS model, hydropower operators can save more water. 

Testing the system with real data

The omnipresent challenge is ensuring supply can always meet demand, even at peak times. How large does the wind or solar farm need to be to supply enough energy when needed in this system?

In Scotland, where there’s an abundance of rain and wind, we tested the DIGS model. We applied it to Glenlee, a 24 megawatt (MW) hydroelectric power station in Dumfries and Galloway.

We worked with real-life operational data kindly provided by our client, Drax, the power station owners. Our team ran an analysis to create a simple model for maximising peak-time generation from a hypothetical wind farm. 

We ran several scenarios, increasing the size of the wind farm to test the results. Interestingly, our analysis showed that peak-time generation from hydropower rose sharply when we tested a wind farm size of up to 3MW but then plateaued when it got any larger. We discovered the same when it came to the amount of water we conserved.

Prioritising wind and solar over hydro generation, using the DIGS model, allows for conserving more water.

This suggests that there is a potential for the perfect wind farm size in the DIGS model. The right-sized wind farm, in combination with hydropower reservoirs, would maximise peak-time generation and water conservation. Storage would support times of low renewable generation, in effect making the combined power resource dispatchable.

Integrating wind or solar power behind the meter and merging them with conventional hydropower is a great option to boost our grid. Hydropower has existing bulk energy storage. Using them together to efficiently store renewable energy and use our existing grid infrastructure in a win-win scenario.

Prioritising wind and solar over hydro generation, using the DIGS model, allows for conserving more water. It gives us more water for generation either at daily peaks or to support more seasonal storage. This could even allow owners and operators to optimise planned dispatch as part of their trading strategies. 

The addition of relatively small batteries into integrated systems could offer further benefits. They can provide very fast frequency response service for longer periods, without relying on large chemical batteries. 

And this is just the start. First, the DIGS model is tested with historical data to optimise potential wind farm size. But we can develop DIGS further. By adding weather forecasting into the model, operators could plan with greater accuracy in expending and conserving each type of renewable resource. And though not a financial model currently, DIGS could, in theory, integrate financial analysis.

Now, imagine if we could use the DIGS model on every suitable hydropower plant. We’re not quite there yet, but we know what the challenges are.

Challenges to overcome to help the energy transition

Using existing hydropower reservoirs as bulk energy storage is a great opportunity. But, honestly, not all existing hydropower stations may be suitable. The turbine, generator gates, and waterways must all be capable of increases in ramp-up and ramp-down rates without impacting plant life and maintenance.

There may also be limitations in the power and flow capacities of units, as well as operating limits of plants and fatigue.  

We need to start with a portfolio approach. That means we look at putting all this combined technology behind a common grid connection. Each offsite opportunity is considered with its relative merits. Variability of releases must also stay within permitted rates and levels.

There also needs to be a comparison of needs between current operating regimes and how they would differ with integrated technologies behind the meter. 

More holistic thinking will contribute to a more sustainable and secure energy future.

The future of the energy transition

There are challenges to overcome. But if we can combine renewables through smart models like DIGS, we can offer the energy sector cost-effective, flexible, and scalable solutions. And we can do it with this in mind—sustainability, affordability, security, and the energy transition.

It will take careful technical consideration and continuous development. With the goal of providing effective and efficient dispatchable systems like this. And it can support the reduction of grid carbon intensity. 

While not a panacea, DIGS and similar smart models can contribute to a more sustainable and secure energy future. They will promote energy equity as we add new sources to the grid. To find out more about how DIGS model thinking could help your operations, contact our team. 

  • Tom Pendrey

    Tom is a principal mechanical engineer who works in a variety of energy technologies—pumped storage and conventional hydropower, solar photovoltaic, and wind power—in design, design review, project management, and technical advisory roles.

    Contact Tom
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