Introduction
Background
The Millennium Seed Bank, constructed in 2000 at the Royal Botanic Gardens Wakehurst, serves as the world’s largest seed conservation project. With 15.6% of the world’s wild plant species currently banked, its primary mission is the conservation of threatened plant species.
Objectives
To maintain the viability of these seeds, they are stored at -20°C in a highly secure, state-of-the-art bunker. The original cooling solution, a R404A refrigeration system, was identified by JC Watson Mechanical, the service provider for Royal Botanic Gardens at Kew and Wakehurst, as needing an upgrade to enhance sustainability and operational resilience.
Methodology
Approach
In alignment with the seed bank's sustainability ethos, JC Watson Mechanical proposed several natural refrigerant options, including Ammonia, R449A and CO2, as alternatives to the existing system.
Implementation
After extensive thermodynamic and life cycle analysis, a Low Temperature Transcritical CO2 booster system was selected for its efficiency and lower environmental impact. This system was designed to reduce direct energy consumption by 20% and save 26 tonnes of CO2e annually.
Results
Achievements
The installation of the CO2 booster system has led to significant energy savings and a reduction in Total Equivalent Warming Impact (TEWI), aligning with the seed bank's conservation mission.
Challenges and Solutions
The design process involved meticulous planning to ensure that the system was resilient, efficient and could operate seamlessly within the existing infrastructure. Key components included ultra-high resilience design, elimination of single points of failure and optimised controls for high efficiency.
Impact
Environmental
The project has resulted in a direct reduction of 26 tonnes of CO2e per year. Additionally, heat recovery technology now saves up to 876,000kWh of electricity annually, further reducing carbon emissions by 204 tonnes per year.
Economic
The energy savings translate into significant cost reductions for the Royal Botanic Gardens, demonstrating the economic viability of sustainable refrigeration technologies.
Social
By adopting a forward-thinking approach to its refrigeration needs, the Seed Bank reinforces its commitment to sustainability, setting a positive example for conservation efforts worldwide.
Lessons Learned
Key Takeaways
This case study illustrates the importance of aligning operational practices with broader environmental objectives. The successful implementation of a more sustainable refrigeration system at the Millennium Seed Bank demonstrates the feasibility of significant energy and carbon savings in critical conservation efforts.
Recommendations
For institutions looking to reduce their environmental impact, this case study underscores the value of thorough system analysis, the exploration of natural refrigerants and the integration of energy recovery solutions for greater efficiency and resilience.
Conclusion
Summary of Findings
The transition to a Low Temperature Transcritical CO2 booster system at the Millennium Seed Bank represents a significant advancement in sustainable refrigeration technology. This initiative not only supports the Royal Botanic Gardens conservation goals but also contributes to the broader fight against climate change.
Future Outlook
The success of this project paves the way for similar initiatives in other sectors, highlighting the potential for significant environmental and economic benefits through the adoption of green technologies.