The Irish Prison Service (IPS) has long been committed to the safety, rehabilitation, and reintegration of those in custody. But in recent years, it has added another mission to its goals—sustainability.

Across prisons throughout Ireland, the service is leading a quiet environmental revolution. With the help of Harp Renewables, they are turning food and animal waste into valuable, nutrient-rich compost. In doing so, they are not only protecting the environment but also giving inmates the chance to build real skills and purpose.

About the Irish Prison Service

Operating under the Department of Justice, the Irish Prison Service manages numerous facilities across the country—from high-security prisons to open centers—each committed to rehabilitation, education, and now, environmental sustainability. Facilities include:

• Mountjoy Prison (Dublin 7)

• Castlerea Prison (Roscommon)

• Cloverhill (Dublin 22)

• Loughnan House (Cavan)

• Portlaoise Prison

• Limerick Prison (Limerick City)

• Cork Prison (Cork City)

• Wheatfield (Dublin 22)

• Arbour Hill (Dublin 7)

• Shelton Abbey (Portlaoise)

A Growing Need for Change

Each year, Irish prisons generate vast amounts of organic waste—from kitchen leftovers to stable bedding. Traditionally, this waste would have been sent to landfill, generating unnecessary carbon emissions and missing opportunities for recycling.

One of the most inspiring examples is at Castlerea Prison in County Roscommon. There, the “Horses of Hope” Equine Centre helps inmates learn to care for animals and develop skills they can use after release. But managing horse waste was a real challenge. The same was true for food waste in kitchens across many prison sites.

The Irish Prison Service needed a solution that would reduce waste, protect the environment, and support rehabilitation.

Harp Renewables Steps In

Harp Renewables worked closely with the Irish Prison Service to install a series of on-site biodigesters—smart aerobic systems that transform organic waste into high-quality compost in less than 24 hours.

We introduced three main models across the prison network: the CX2, CX5, and CX10. Each one is tailored to the specific needs of the facility, whether it’s processing kitchen scraps or horse manure.

Here is an overview of the systems installed across IPS facilities:

Model Highlights: Harp CX2, CX5 & CX10 Biodigesters

The Harp CX2 processes up to 2,000 litres of organic waste per week and can reduce the amount of waste sent to landfill by up to 80%. It is compact, efficient, and perfect for smaller facilities.

This model has been installed in prisons including Shelton Abbey, Portlaoise, Mountjoy, and Arbour Hill in Dublin. It is equipped with advanced sensors that monitor and adjust key parameters like temperature and pH, ensuring consistent performance. Built-in safety features prevent overpressure and ensure safe operation at all times.

The Harp CX5 works in a similar way to the CX2 but with a greater capacity. It can process 5,000 litres of waste each week, making it suitable for medium-to-large facilities.

This model is in use at Castlerea, Cloverhill, Loughan House, Portlaoise, Wheatfield, Cork City, and Limerick. At Castlerea Prison, two CX5 units are in operation—one for food waste from the canteen, and the other for horse manure at the Equine Centre. These machines are not only improving waste management but are also central to the prison’s rehabilitation efforts. Inmates there now gain hands-on experience with the machines, learning about sustainability and waste processing while making a meaningful contribution to their community.

The CX5 also includes a built-in bin lifter that automates waste input, reducing manual labour and improving safety.

Specifications:

• Equipment: Harp CX5 with bin lifter and actuator on door
• Waste Stream: On-site canteen waste, kitchen waste.
• Capacity: 715 Litres/Day, 5000 Litres/Week, 260,000 Litres/Year
• Estimated CO2 Savings: -3227.4 KgCO2eq (- 3.2 Tonnes CO2eq )

The Harp CX10 is the largest of the three systems. It is designed for high-volume food waste processing and can convert up to 10,000 litres of organic waste per week. This model has been installed in Mountjoy and Portlaoise prisons.

The CX10 is fully automated and features a built-in bin lifter, making it simple and safe to operate. With minimal need for manual input, it allows facilities to streamline their operations and focus on other aspects of rehabilitation.

Real Results That Matter

The results across the prison system have been exceptional. At Castlerea Prison alone, waste volume has been reduced by 75%, and the compost produced is used to enrich the soil in prison gardens.

Each installation is more than just a piece of equipment. It’s a tool for learning and rehabilitation. Inmates who operate the machines gain valuable knowledge in environmental management—skills that will serve them well after release. The biodigesters also contribute to each prison’s long-term sustainability goals by closing the waste loop and significantly reducing emissions.

Recognition and the Road Ahead

This remarkable success was recognised nationally when Harp Renewables won the “Innovation in Waste Resource Products or Services” award at the 2023 PakMan Awards in Dublin. The judges praised the partnership with the Irish Prison Service for its innovation, social impact, and contribution to Ireland’s circular economy.

Click here, for an insert from RTE News, showcasing our win at the Pakman Awards 2023.

Today, the Irish Prison Service is not only managing waste better—it is leading by example. The integration of Harp’s technology has reshaped how prisons think about sustainability and rehabilitation. Inmates are learning skills. Prisons are reducing their environmental impact. And a more hopeful, greener future is being built from the ground up.

As this model proves its value, Harp Renewables is working to expand this model to correctional facilities in the UK, the United States, and beyond—sharing the success of this program with a global audience.