Can we find more effective ways to store and integrate excess renewable energy? That was the task at hand for this project, using Dublin’s Poolbeg area as a case study.

We all know the best way to eliminate needless waste is to reduce, reuse and recycle – but can we find more effective ways to store and integrate excess renewable energy? That was the task at hand for this project, using Dublin’s Poolbeg area as a case study. The team set out to explore how coupling of the electricity, heat and transport sectors can ultimately facilitate our national net zero objectives.

About the project

The Poolbeg project investigated how to make use of curtailed or wasted renewable energy from offshore wind, from the nearby waste-to-energy plant in Poolbeg. The research (led by Codema and MullanGrid Consulting, with collaboration from Dublin City Council and Dublin Waste-to-Energy) focused on how district heat with thermal storage, and a separate hydrogen electrolyser, along with curtailed renewable electricity and hydrogen end-use applications, can provide an efficient, integrated energy system solution.

This project was funded under Topic 6 of the SEAI RD&D Call 2021; Measures to reduce dispatch down (curtailment and constraint) of renewable electricity generation.


“One of the main challenges in connecting renewables is when you try to integrate them into a system what do you do with all that energy? To reach 80-100% renewables, you need close to 200% renewables installed. Why? Because the wind doesn’t blow all the time and the sun doesn’t shine all the time, so to compensate for this we need to produce more. This means you end up with curtailment, or wasted energy, where renewables are being turned off”, explains Rory Mullan of MullanGrid Consulting.

As we generate this excess energy, the question arises as to how best to store it; could looking across the sectors provide an answer? Gas molecules can be stored, and oil can be placed in a tank, but what can you do with electricity? The traditional method of storing electricity in pumped hydro or in battery storage has its pitfalls — it’s expensive and can mean significant land take.

“When we looked at curtailment and what is done at the moment in terms of storage on the network to limit waste, we compared battery energy storage systems with thermal energy storage options that we would have as a district heating network,” explains John O’Shea, Codema Senior Energy Systems Analyst. “Thermal energy storage performs really well in terms of cost, compared to battery storage. One of the interesting things we found was that thermal energy storage took up significantly less land area than the battery storage systems, the way they are laid out at the moment.

District Heating

District heating systems deliver heat designed for both space heating and water heating to buildings through a network of insulated underground pipelines. In much the same way as electricity is delivered to our homes and buildings, energy in the form of heat is produced centrally in large plants and delivered through a district heating network. A proven technology that is already being used extensively in countries like Denmark, district heating  is also successful in storing excess renewable electricity; this research backs up the findings that Dublin, specifically the Poolbeg area with its offshore wind, is an ideal place to implement this in Ireland.

“The integration aspect here is really important. Up until now in the renewable journey, the electricity, heat, and transport sectors have worked separately in this area with limited integration”, explains Rory Mullan of MullanGrid Consulting. “To get to zero carbon energy, how the electricity, heat and transport sectors work together will be essential. We know that the most effective way of generating renewable energy is electricity — wind farms, and solar farms as examples — but the best way of storing electricity or energy may not be within the way we have traditionally, like battery or pump storage; it could be better within the transport or the heating sector in thermal storage.”


The project resulted in a renewable energy vision for the Poolbeg area of Dublin City across the electricity, heat and transport sectors and provided several outcomes, including:

  • development of 2030 and 2040 wind energy curtailment scenarios, including curtailed energy profiles
  • development of an analysis of future H2 potential in Dublin
  • development of a green H2 production model, in the context of resources available in the Poolbeg area of Dublin
  • development of a district heating and thermal storage model in the context of resources available in the Poolbeg area of Dublin

Read the SEAI’s 2022 National Heat Study.

Project partners

  1. Codema is Dublin’s Energy Agency and aims to accelerate Dublin’s low-carbon transition in order to mitigate the effects of climate change and improve the lives of citizens.
  2. MullanGrid Consulting is an electrical engineering consultancy specialising in the grid connection of renewable generators.
  3. Dublin Waste to Energy provides sustainable treatment of waste that cannot be reused or recycled, converting it into renewable energy.
  4. Dublin City Council is the authority responsible for local government in the city of Dublin in Ireland.

The SEAI research team funds and supports research and innovation across the energy sector to help build a cleaner and more secure energy future. We invest in projects in Ireland and identify areas of priority for Ireland and Europe, helping to enhance the world’s knowledge economy.

Download summary, policy brief and full report    SEAI Research and Innovation Funding Call