Turning Waste Heat into Working Capital
For centuries, alchemists chased the impossible—trying to turn lead into gold. Modern science put that myth to rest, but in aquaculture, a kind of practical alchemy still exists. With the right system design, ordinary materials like titanium and steel can be transformed into something far more valuable: dramatically lower energy costs and healthier, more profitable stock.
That’s exactly what heat recovery does.
In a recirculating aquaculture system, heat recovery captures energy that would otherwise be thrown away and redirects it where it’s needed. The principle is simple: every litre of water that enters a tank must eventually leave it. If that tank is being held at 21°C and your incoming water is 1°C, your heating system has to overcome a 20-degree temperature gap.
With a properly designed heat recovery system, that gap can shrink to just 2 degrees. Instead of heating cold water from 1°C all the way to 21°C, you’re only topping it up from 19°C to 21°C. That represents an order-of-magnitude reduction in energy demand for that input.
Here’s how it works: once a tank is full, every litre per minute added creates an equal litre per minute of effluent—already warmed to tank temperature. A heat exchanger transfers that thermal energy from the outgoing stream to the incoming water. No pumps. No motors. No additional power. Just physics doing its thing.
In many systems, the energy captured passively through heat recovery can rival—or even exceed—the contribution of the active heating equipment.
High
Stakes
Because the stakes are high, these systems aren’t something to improvise. There are three realities that separate effective heat recovery from expensive disappointment:
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Influent and effluent flows must match precisely. That’s rarely trivial in real-world systems.
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Plate heat exchangers, while efficient, foul easily. Without mitigation, they can drop from 80–90% efficiency to under 10% in days. Proven solutions exist—and they pay for themselves quickly.
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Heat exchanger design is a discipline of its own. Oversizing, poor material choices, or improper flow characteristics can increase cost, complexity, and energy use rather than reduce it.
The Real Alchemy
When done correctly, heat recovery becomes one of the highest-ROI features in a modern RAS facility. It lowers operating costs, improves thermal stability, and often qualifies for energy-efficiency incentives.
At APS, we design, supply, install, and maintain dozens of heat recovery systems every year in seawater RAS operations. This is not a bolt-on afterthought—it’s a core part of building systems that perform efficiently, predictably, and profitably.
Real alchemy isn’t about magic. It’s about knowing where the hidden value lives—and how to unlock it.