Is sector coupling the answer to renewable intermittency?

TL;DR

• Sector coupling is a new way of thinking that aims to integrate different energy sectors to maximise their efficiency and compensate for the fluctuations associated with renewable power generation.

• In a coupled system, electricity, heating, cooling, gas and Power-to-X technologies are all connected so that they can easily exchange energy with one another. Digitisation supports with resource management and smart storage solutions hold energy until it is needed.

• This new approach has potential to transform the industry, buildings and transportation, powering electrification and finding ways that they can contribute to the grid in return.

• Denmark is a pioneer in sector coupling. A whole host of projects are finding new ways to generate, store and transfer energy around communities, making use of waste power wherever possible.

• For sector coupling to fulfil its potential, effective energy management, infrastructure improvements and knowledge sharing will all be needed.

The detail

When faced with a goal as ambitious as net zero by 2050, finding creative and innovative ways to unlock the full potential of renewable energy is essential.

Sector coupling is one such innovation. This approach to energy management aims to integrate different energy sectors to maximise their efficiency. In a coupled system, electricity, heating, cooling, gas and Power-to-X technologies are all connected, meaning they can easily exchange energy with one another.

This is a new way of thinking. It takes a more holistic view of the renewable energy landscape and one that prioritises innovation and interconnectivity, breaking down the barriers between energy users and energy producers. In fact, most sector coupling initiatives combine at least two different sectors within energy demand and production.

Not only can sector coupling help reduce carbon emissions, but it also has the potential to solve some of the biggest roadblocks hindering the advance of the renewable energy industry. Fluctuating supply, infrastructure pressure and high costs threaten to slow down the energy transition. Both wind and solar power, for example, have an important role to play in electrification, but they aren’t consistent in their power output and robust storage solutions are currently lacking. Unfortunately, this means they can’t solely be relied on to produce energy when we need it most. By following the principles of sector coupling, the flexibility of energy systems can be enhanced, and a higher share of renewables (from a range of sources) can be integrated into the grid.

Harnessing excess energy

Sector coupling is often closely associated with technologies designed to reduce emissions and effectively balance the grid. Electric vehicles (EVs) and heat pumps are both prime examples – the batteries in EVs, for example, can be used to reinject power into the grid at times when it isn’t in use.

Sector coupling also makes use of energy that would otherwise be wasted. Heat generated as a by-product during industrial processes can be used to warm spaces or generate electricity, excess wind and solar power can produce hydrogen via electrolysis, and electrode boilers use electric currents to heat water.

When it comes to innovative initiatives, smart grids, large-scale energy storage and green hydrogen production are all related to smart coupling, while digitisation plays a supporting role by helping to optimise the way energy moves around the grid.

Major benefits could be reaped

Sector coupling has the potential to improve energy efficiency across several different areas – in particular, buildings, transportation and heavy industry.

Buildings are already adapting the way they operate, embracing electrification by adopting both electric appliances and heat pumps. The value of heat pumps in decarbonising heating and cooling is now being more widely recognised, and it’s predicted that the number of pumps powering buildings in the UK is set to grow from 52 million in 2022 to 142 million by 2030. This shift is being supported by financial incentives including tax breaks, grants and rebates.

However, it has not been a seamless transition. Existing electricity infrastructure is not always aligned with heat systems and additional investment will be required to enhance the electricity distribution network. Suppliers also need to mitigate issues caused in peak periods by implementing smart operation systems to not only track demand, but also proactively share price and energy signals with consumers.

One of the industries that could benefit most from sector coupling is transportation. EVs are powered entirely by batteries and release zero emissions, making them cleaner to run than petrol and diesel vehicles. In recent years, sales have been increasing in China, EU and the US, but adoption is still limited by minimal infrastructure and battery limitations.

This could be addressed through sector coupling and digitisation, which can help standardise capacity and balance the energy demand on the grid. Smart charging can be used to reduce peak demand and improve system flexibility, transformer capacity upgrades could boost efficiency, and introducing standardised charging plugs could increase uptake of public charging points.

Benefits go both ways. Vehicle-to-grid and vehicle-to-building connections can transfer excess EV battery energy to provide supplemental power for buildings and benefit the power system by supporting mini grids and reducing network outages. Indirect electrification can also help to decarbonise transportation as green hydrogen and liquid fuels can be used to reduce emissions.

Heavy industry is one of the most challenging areas of the economy to decarbonise due to its reliance on extreme heat. However, there are options which could help to overcome roadblocks such as cost, energy density, technology maturity and infrastructure that prevents electrified methods from reaching the required temperatures. Concentrated solar thermal systems can provide carbon-free heat, while geothermal and biomass heat could offer another viable alternative. Heat pumps, meanwhile, can be used at lower temperatures. Electricity produced by industry can also be used to charge EVs as well as powering electrolysis (hydrogen production).

A case study from Copenhagen

Denmark has been leading the way in sector coupling, fostering collaboration between the government, industry and academia. The pressure is on – the Danish parliament has a legally binding target to reduce its greenhouse gas emissions by 70% by 2030 and is aiming to be climate neutral by 2050. For it to meet these targets, Denmark knows that its energy systems must be more integrated.

The country has several initiatives spanning different industries which are proving the myriad benefits of sector coupling. The Nordhavn community in Copenhagen, for example, is something of a flexible energy testing ground. With the help of intelligent energy components designed by Danfoss, the community can transport heating and cooling between buildings. The district also uses heating substations with ultra-low temperatures, remotely controlled radiator thermostats to regulate building temperatures, and excess heat generated by its supermarket’s cooling system.

A similar approach has been adopted by the district heating transmission company, TVIS. By collaborating with public and private partners, it has decided to base the heating supply for four municipalities on surplus heat. It takes this heat from multiple sources and redistributes it through a large-scale transmission network – this significantly improves the districts’ heating efficiency and reduces their carbon emissions.

Both public and private institutions are experimenting with sector coupling to reduce their emissions. Arla Foods, based in Videbaek, is building its own electric heat pump facility to cut greenhouse gas emissions by 14,500 tonnes each year and replace its gas-fired boilers. The new facility will convert 2.8 MW of electricity into 8 MW of heat and 5.7 MW of ice water for cooling.

In the public sector, Sygehus Sonderjylland hospital has worked alongside Energy Machines to replace its gas- and oil-fired heating and boiler systems with large-scale electric heat pumps. This enables it to use heat recovered from the existing cooling facilities of its scanners, outpatient clinics and wards. In addition. any excess heat can be sold to the district and channelled into the grid.

Just west of Copenhagen, the Pit Thermal Energy Storage facility in Hoje Taastrup is helping to offset the intermittency of renewables. A 70,000-square-metre and 16-metre-deep unit functioning as a thermal battery, it has a capacity of 3,300 MWh and can store water at almost boiling point for months, ready to be discharged into the heating network when demand increases.

Alternative fuels are also being adopted by both the Danish shipping industry and local utility companies thanks to sector coupling. Maersk is constructing the world’s first large-scale commercial green methanol plant, which will convert solar power into e-methanol. Its three 17.5 MW electrolysers could produce up to 6,000 tonnes of green hydrogen each year – this will be distilled into e-methanol which is used by the likes of LEGO and pharma firm Novo Nordisk.

The excess heat generated is expected to warm up to 3,300 nearby households. In contrast, HIFOR, the Greater Company utility company, is testing Power-to-Gas technology to convert carbon dioxide and hydrogen from wastewater into e-methane. These experiments are expected to increase green gas quantities by 66%.

Pitfalls and potential

The biggest driving force behind sector coupling initiatives in Denmark and elsewhere is the reduction in emissions it offers. Furthermore, not only does it lower the need to use fossil fuel energy, but it can also allow companies to generate extra income by feeding excess energy back into the grid.

However, there are several improvements that will need to be made if sector coupling is to be more widely adopted.

The first is infrastructure optimisation, as the grid is already struggling to manage the uneven flow of energy provided by renewables and effectively transport it to other locations. This could be improved by proactive smart energy management. Digitalisation is one avenue, as technology can be employed to observe, forecast, monitor and control the distribution of renewable power. Governments can also support this process by implementing a regulatory framework to ensure flexible services are developed alongside sector coupling initiatives.

While Denmark serves as a case study of the different possible use cases and the impact they can have on local communities, sector coupling is still restricted to developed countries and specific scenarios. Raising awareness of the practice, and prioritising a knowledge exchange between nations, can lead to success stories like the Bunhill heat network in London. Here, warm air is extracted from metro tunnels beneath its plant and used to heat water in 550 surrounding homes and a local school, as well as power communal lighting and lifts in an adjacent tower.

While it’s not yet a perfect solution, sector coupling represents a shift in thinking and a fresh approach to energy management that is built for long-term success. Combining innovation and collaboration, sector coupling reduces emissions through efficiency and creative resourcing. Rooted in sustainable development thinking, it can be rolled out on a global scale and represents an actionable way to move towards a low-carbon future.

— Lew 👋

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