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Early-stage design and circularity

Results from Work Package 1’s preliminary assessment

HydroCool’s Work Package 1 has completed its initial design and assessment phase. This update summarizes the early-stage results, including Task 1.4, which focuses on the circularity and cost analysis that will shape the next phases of development.

Background

In HydroCool, WP1 is where the project turns a promising cooling concept into a measurable plan: we define how the system should work, under which conditions it will operate, and which KPIs will be used to judge success; this is before moving into detailed design and prototyping.

A key part of this groundwork is Task 1.4, led by AristEng, which brings circularity-by-design in from the very start, to mitigate environmental and economic burden. This is especially important for one of the toughest challenges in cooling: deep-freeze applications (−40 to −10°C).

Understanding the scale

To give a sense of scale, the preliminary assessment was done for a representative system size of 238–281 kW of cooling capacity. That’s roughly like a freezer system of a supermarket, or a cold storage warehouse.

Some early results help illustrate the potential impact:

  • A preliminary analysis indicates ~34% electricity-demand mitigation, driven by ~20% mechanical energy recovery plus reduced compressor energy needs versus conventional approaches (modelling-based, early-stage), highlighting the benefits derived by the design.
  • HydroCool liquid piston compressor has lower maintenance requirement and greater lifespan, since it has fewer moving parts, and less friction compared to conventional gas compressors.
  • Material pre-selection led to stainless steel for HydroCool equipment, due to the combination of good mechanical properties and corrosion resistance, excellent recyclability and relatively low environmental footprint of construction phase (~0.2–0.4 kg CO₂-eq per kW of cooling capacity).

Environmental and economic impact

To quantify the environmental impact, WP1 applied a cradle-to-gate Life Cycle Assessment (LCA), considering the impact of all steps between the resource extraction and the product (cooling) output before it is transported to the consumers. The preliminary assessment highlights a >50% mitigation of environmental impact, compared to conventional refrigeration systems. Regarding economic impact, a mathematical cost model was developed to estimate a levelized cost of cooling of ~0.2 €/kWh. WP4 includes a detailed LCA and TEA of HydroCool system, based on the inputs and updates of future findings of HydroCool during pilot design, construction and operation.

The WP1 assessment also covered both main ways CO₂ systems can operate:

  • Subcritical: CO₂ stays below its critical point and condenses back into a liquid (a more “classic” refrigeration behaviour).
  • Transcritical: CO₂ goes above its critical point, so it doesn’t fully condense into a liquid on the high-pressure side and needs tighter pressure optimisation for efficiency. Transcritical systems apply to hot climate regions.

This WP1 work supports our milestone on preliminary cost and circularity assessment. Aligning technical, environmental, and economic KPIs from the start ensures HydroCool moves toward prototypes with a clear understanding of performance targets and the system’s potential impact.

Authors: Guillem Figueras & Spyros Kyrimis