Why has Northern Ireland’s growth in renewable energy use stalled? In 2005, only 3% of local electricity came from renewables yet by 2020 it was almost 50%. It has remained around the same level ever since. What are the barriers preventing further green growth?

This is the second article in our series on green energy in Northern Ireland. The first piece focused on NI’s renewables boom up to around 2020 and the stagnation since.

This article looks at current and potential sources for renewable electricity generation in Northern Ireland, with some details about the pros and cons of each. It also focuses on some of the wider obstacles that stand in the way of further growth in local renewable capacity.

These, as you will see, have little to do with a lack of renewable sources. Instead, issues with the current state of the grid, especially capacity in transmission and storage, are the chief barriers to progress:

  • The NI grid requires significant upgrades to its ability to both transmit and store energy.
  • Many renewable sources, such as wind and solar, do not provide a smooth supply of power. Currently there are times when renewables generation is much higher than the grid can handle – with the resultant surplus energy simply being wasted.
  • In 2024, renewable generators were turned off or down 30% of the time because the grid could not absorb their output. Right now, our domestic transmission and distribution system is not sufficient to allow NI to meet its 2030 renewables targets.
  • Work is also required to increase international connections. The new North South Interconnector is set to be a vital piece of infrastructure but development is beset by delays.
  • Storage is also an issue. Local capacity to store energy in both the short- and long-term needs more investment, while some even longer-term options face geographical obstacles too.

Read on for more details.

  • The Electricity System 

One key focus of this article is electricity generation, for example by wind turbines and solar panels. Most of us will be familiar with the other end of the electricity system, supply, where a selection of companies provide energy to homes and businesses in NI. 

The middle step, which is the other core subject of this article, relates to the transmission and distribution networks which connect generation to supply. This includes interconnectors, substations, transformers, pylons, transmission lines, ground wires, insulators and distribution lines.

All of these taken together are referred to as the electricity grid.

Figure 1 – source: Power NI (via the Northern Ireland Affairs Committee)

  • Renewables in NI

Almost half of electricity generated in NI in 2025 was from renewable sources. The vast majority of this is from onshore wind.

Figure 2 – source: NISRA

While nearly 50% of electricity generated in NI in 2025 was from renewable sources, NI still relies on gas-fired power stations to provide baseload power (the minimum amount of electricity needed). 

The statutory target set by the Climate Change Act (Northern Ireland) 2022 is for at least 80% of electricity consumption to come from renewable sources by 2030. 

So what are the current, and the possible future, sources of electricity generation that could help NI reach its target?

  • Onshore Wind

Onshore wind currently makes up 73% of the renewable energy generated in NI. This sector burgeoned in the 2010s, thanks to a UK Government incentive scheme. In the absence of any current incentive scheme, growth in onshore wind electricity flatlined in the 2020s. However, there are still well over 100 planning applications for wind turbines currently in progress.

Northern Ireland has some of the best wind resources in Europe. However, wind is also intermittent and seasonal. Sometimes winds are too light for turbines to generate significant amounts of electricity, while at other times wind is so plentiful that not all of the power produced can be used.

This has led to a significant amount of wind energy in NI being wasted. ‘Dispatch down’ is when wind turbines (or any other renewable generator) are switched off because the grid does not have the capacity to use the amount of renewable energy produced.

We will look at the grid issues in more detail below but, in short, we have reached the point where NI sometimes has more wind energy available than the current system can effectively use.

  • Offshore Wind

Northern Ireland currently has no operational offshore wind farms. However, it does have suitable topography and potential for offshore wind, particularly for floating systems in areas of deep water.

Offshore wind has both advantages and disadvantages. Offshore turbines can utilise powerful wind speeds, and produce more consistent electricity than onshore wind. With increased scale, however, comes increased costs, both to construct and to integrate into the existing grid system.

The Department for the Economy has an action plan to deploy offshore wind from 2030. Developers have committed over £100 million to develop Belfast Harbour as an offshore wind hub, while the port itself is investing a further £90 million in a new deepwater berth. It is also working with the Port of Cork to establish Belfast and Cork as critical hubs for wind farm projects in the Irish Sea. Consultation and legislation paving the way for offshore wind are in progress.

A 2025 NI Assembly Report sounds a note of caution, however, pointing to a number of Scandinavian offshore wind companies withdrawing from UK markets due to inflation in the price of steel and rare earth metals, and a shortage of vessels.

  • Bioenergy

Bioenergy amounted to 19% of NI’s total renewable energy mix in 2025. This was in the form of biomass, such as wood pellets or imported fuels burned in generators, and biogas – mainly anaerobic digestion (AD) of agricultural waste, manure and food waste.

This sector grew rapidly during the 2010s, supported in part by the Renewable Heat Incentive (RHI) scheme, until its closure to new applicants in 2016.

Unlike wind and solar power, bioenergy can be used on demand, making it a potentially stable source of renewable electricity and heat when weather conditions are unfavourable. Another advantage is that NI’s large agricultural sector provides substantial waste products for anaerobic digestion.

However, bioenergy raises environmental concerns, particularly around the sustainability and carbon impact of some imported fuels. Storing silage and other waste stock on AD facilities also creates ammonia, a form of nitrogen, which is harmful to biodiversity and can cause eutrophication, as we have seen in Lough Neagh.

An additional 1% of NI’s renewable energy comes from landfill gas, for example at the Cottonfield Landfill Site in Belfast. This is a form of bioenergy. When organic waste decomposes in landfill sites, it generates methane which can be captured and used to generate electricity. 

However, the contribution of landfill gas is likely to remain limited, as policy increasingly focuses on reducing the amount of biodegradable waste sent to landfill.

  • Solar

Solar energy in NI is growing, but contributed only around 6% of the renewable energy mix in 2025. NI is not known for being particularly sunny, but solar panels can still produce power on cloudy days.

A key advantage with solar energy is that panels can be installed in diverse locations such as homes, businesses and public buildings, allowing consumers to generate their own electricity. Solar also complements wind power by generating electricity at different times of day and in different seasons.

As the cost of solar technology has fallen significantly in recent years, it could become an increasingly important part of Northern Ireland’s energy mix in the future. Batteries can be fitted in consumers’ homes and premises to store solar energy locally; we’ll discuss the efficacy of battery storage later in the article.

  • Hydro/Tidal

Hydroelectric power contributes a small amount (1%) of renewable electricity to the local total, generating electricity by using flowing water to turn turbines. It consists of small, localised schemes using rivers and existing water infrastructure.

While hydro can provide reliable, predictable generation, opportunities for significant expansion are limited by lack of suitable locations, although a feasibility study is underway in Carrickfergus, using water from Belfast Lough.

The SeaGen turbine pilot project operated in Strangford Lough between 2008-2019 but generated only a very small amount of energy in the context of NI’s overall system.

While tidal energy is predictable and has attracted research interest because of Northern Ireland’s coastline, the technology remains relatively expensive and less developed than wind and solar power.

  • Geothermal 

Geothermal energy uses heat from beneath the Earth’s surface to provide electricity or heating. The UK has a geothermal energy pilot in Cornwall, where local geology is particularly favourable. 

  • Nuclear

Nuclear power is not a renewable energy source. However, it is a low-carbon source of electricity and is often included when thinking about energy security. 

Unlike wind and solar power, nuclear stations can generate electricity continuously regardless of weather conditions, and would be capable of providing reliable baseload power.

Supporters argue that future technologies such as Small Modular Reactors could provide reliable low-carbon electricity, while critics point to high costs, lengthy construction times and the challenge of managing radioactive waste.

NI does not currently have any nuclear generating capacity. While nuclear power forms part of the wider UK energy strategy, it does not currently feature prominently in NI’s renewable energy plans.

  • Grid networks – a key challenge

The wider electricity grid connects energy generation to electricity suppliers and end users. Without transmission and distribution networks, energy generated is wasted.

NI’s electricity system operates as part of the all-island Single Electricity Market (SEM), operated locally by SONI (System Operator for NI) and by Eirgrid south of the border. In the SEM, electricity is traded and dispatched across NI and the Republic of Ireland as a single wholesale market.

In fact, the wider grid is just as important as generation in moving NI towards its 2030 renewables target as forms of generation and, as we shall see, issues with grid capacity – and, in particular, storage – are perhaps the biggest obstacles to growth in local renewables usage.

  • Interconnectors

Electricity interconnectors are high voltage cables that connect NI to wider electricity markets. Interconnectors are crucial, because renewable energy is traded and shared between neighbouring systems to help manage surges and demand.

NI is connected to Scotland via the Moyle Interconnector, and to Wales and ROI via the Greenlink Interconnector. A Celtic Interconnector between ROI and France and a further East West interconnector are in development.

Given the all island SEM, a crucial interconnector for NI is the North South Interconnector. The existing North South Interconnector is at full capacity. This means that the grid in NI cannot direct any further electricity to ROI when it is unable to handle all the renewable energy being produced in the north. This increases local reliance on gas for baseload power.

Plans for a new North South Interconnector were first proposed in 2006. It is a key part of SONI’s £630m grid investment plan for 2023-32. SONI says it will remove a major bottleneck in the grid and become “the backbone of the transition system.” However, the project has experienced significant delays. It is now expected to be operational in 2031 rather than 2027 due to a planning delay south of the border.

Analysts Cornwall Insight has warned of the catastrophic impact of the delay to the North South Interconnector on NI’s ability to meet its renewable targets. The delay could also affect any shift to renewables and increase bills in ROI.

  • Domestic grid

RenewableNI has identified a number of challenges with NI’s domestic grid infrastructure, for example: a lack of investment over the last 10 years, a lack of forward planning, a skills gap in delivering grid improvements and burdensome planning requirements.

An underdeveloped domestic grid has a direct impact on energy supply. For example, in 2024, through a process known as ‘dispatch down’, renewable generators were turned off or down 30% of the time when they could have been generating, because the grid could not absorb their output.

SONI’s grid investment plan for 2023-32 includes significant upgrades to the domestic grid in NI. However, a 2025 overview by NI Public Policy Think Tank Pivotal, says that some improvements – the Mid Antrim Upgrade and Mid Tyrone Project – are years behind schedule. It concludes that:

“[Without] these projects, the grid can’t handle the clean electricity already being produced … This wastes cheap, renewable power and increases reliance on fossil fuels. This is often due to network constraints, particularly in wind–rich areas like the northwest, preventing electricity travelling from generation points to demand centres where it is needed.”

Overall, NI’s domestic transmission and distribution networks are not currently fit for the purpose of meeting the 80% renewable energy target by 2030. The promised investment would make a significant impact, but delays are seriously impeding progress.

  • Storage

So far we have discussed the movement of electricity in real time. But energy storage also has the potential to make an impact on how much existing renewable electricity generation NI can utilise.

Batteries work by storing excess energy generated, for example during the day from solar, or at peak times of wind, which can be released back into the grid later when it is needed. Battery storage is growing within the all-island system, in homes as well as in larger storage projects, and is projected to grow significantly by 2030.

Batteries are particularly effective at storing electricity for short periods, for example over the course of hours or a day. However, they are not generally considered a practical solution for storing large amounts of electricity over weeks or months.

For this reason, low carbon hydrogen – produced using surplus renewable electricity – has been identified as a possible longer-term storage solution, particularly if large volumes of offshore wind come online beyond 2030. A consultation on low carbon hydrogen was launched by the Department for the Economy (DfE) in September 2025.

However, a 2025 report commissioned by DfE found that hydrogen is economically challenging, but may still have a role in energy storage and transport fuels, although this depends on large-scale offshore wind that does not yet exist. 

There are also mechanical storage options, for example pumped hydro storage. This stores energy by pumping water uphill, releasing it later when needed. This is the most established large-scale electricity storage technology globally. It is not currently present in NI, and its development is likely to be limited by topography.

Another relevant mechanical energy storage method is compressed air energy storage (CAES). This uses surplus energy to compress air, often to the point of liquefying it, which is used to drive turbines to generate electricity. The high pressure air can be pumped into large, airtight underground caverns, which can be created by removing salt from the ground. NI has some places which would be suitable for this, and Islandmagee Energy has plans to build a site under Larne Lough, but so far this has been blocked by an environmental campaign group.

  • Managing demand

In addition to storage, demand side management is another option to get the most out of renewables. This could include meters, time-of-use tariffs, or demand flexibility – which encourages consumers to use electricity when renewable energy is plentiful  (or penalises them for use when it is scarce) – for example electric vehicle charging timed to overnight wind surpluses.

While not a traditional grid update, it could play a role in NI getting the most out of the renewable energy it generates. Nevertheless, one inherent downside is that it places conditions/restrictions on consumer energy use.

  • Conclusion

NI has natural advantages in renewable energy. It has some of the best wind resources in Europe, a large agricultural sector well-suited to bioenergy, and growing solar capacity. Nearly 50% of electricity generated in 2025 came from renewable sources, which is a significant achievement.

However, the gap between 50% and the 2030 target of 80% is huge. NI’s issue is not primarily one of generation – it is already producing more renewable energy than it can use. The challenge comes from a grid that cannot absorb what is generated, interconnectors at full capacity or years behind schedule, and storage infrastructure still in its early stages. 

All of these problems are solvable but require sustained investment, faster planning processes, and political will.

We will explore what that might look like in practice later in this series. Our next article will look at how NI compares with other countries – including the rest of UK and Ireland, and elsewhere in the UK.