FloatPac Solar floating solar systems offer a wide variety of water saving benefits which value add to the prospect of floating solar over bodies of water.

Floating solar systems naturally aid in the reduction of evaporation, thanks to the shading of the bodies of water which they cover.

As the world, and particularly dry countries, such as Australia, grapple with water scarcity and security, FloatPac Solar systems help aid this issue, shading the very water the solar arrays are floating on.  This shading provides two main features:

  1. The shading effect inhibits evaporation of the water catchment area directly below the floating solar system, preserving that water which would otherwise simply naturally evaporate
  2. Installations that cover 75 – 80% of the body of water in which the floating system sits upon also help to inhibit algae growth.

 

Evaporation control

Water in Australia is bought and sold too cheaply, it is a limited commodity for which we feel an entitlement.

The recent 2019 drought has provided some perspective on the value of water and how its value is determined when its availability becomes scarce. Along with the 2019/20 bushfires, it underscores the importance of climate action and why 2050 targets whilst admirable may be too little / too late.

As an example, Sydney Water is located within average evaporation zones between 1400 and 1800mm per annum. It’s STP’s have commonly already been re-labeled as “WRP’s” and the bulk of its water bodies are typically treated effluent. With predicted population growth of 60% to 2050 within Sydney Water’s regulatory area, the reliance on treated effluent to service a high proportion of the increased demand is inevitable.

Water NSW assets, on the other hand, contain raw water suitable for population, and demand from their assets will increase over time with population growth. Water NSW has the surface area, but seldom the corresponding energy consumption, to make floating solar commercially viable. Sydney Water’s Water Treatment facilities at Prospect, Cascade, Woronora and Nepean WTP’s, provide the opportunity for commercially viable behind the meter floating applications providing wholesale water conservation benefits in the identified zones averaging between 1400 and 1800mm water evaporation per annum, which is a new evaporation benefit of floating solar which is available from FloatPac Solar that is currently not available with any large scale renewable energy product offering.

Algae Control

Reducing light penetrating the water surface is a time tested and proven method for reducing algae control.

Several algae control technologies simply make waves to reduce light immittance. A cover is the ultimate algae control, but the costs of covers in comparison to chemical and mechanical solutions have historically made this cost-prohibitive. Where the cover can provide a separate revenue stream in the form of renewable energy generation, the combined scenario becomes commercially advantageous.

For example, a recent FloatPac investigation found Sydney Water’s covered areas is in an average peak sunhour zone of 6-7.  Whilst not as extreme as in northern areas, the nature of manmade lined lagoons results in higher temperatures than natural water bodies. In Sydney Water’s scenario, treated effluent retains high levels of nutrient making these more susceptible to algae blooms. This currently means significant annual funds are allocated and generally spent in an effort to mitigate and control algae blooming at various Sydney Water sites, and FloatPac Solar would not only go a long way to removing a large percentage of this annual spend, but it would also provide an ongoing revenue stream.

The nature of a floating solar cover also provides significant temperature benefits. The FloatPac Solar system includes solar panels mounted 100-400mm providing shade over approximately 85% of the foundation structure, which in itself is a 180mm thick insulating air cushion. Through peak summer temperatures, when the black HDPE lined lagoons conventionally draw in heat, the core water temperature of bodies hosting floating solar will be far reduced. The cooler temperature will further limit the propensity for algae growth.

How much water can FloatPac’s floating solar systems save?

 

Reductions of up to 600 – 700 litres / m2 / year have been reported by various floating solar systems since they were first installed.  This corresponds to a reduction of around 80 – 90% of total water loss through evaporation where FloatPac Solar floating solar farms are installed.  There are two key factors when considering these reported reductions:

  1. The shading effect of floating solar over water surfaces yields a reduction of approx 30 – 40% per year.
  2. Intercepting and reducing wind over the water surface (whilst carefully ensuring natural oxygenation is not affected) can yield reductions of 40 – 50% per year.

Combining these figures, in conjunction with looking at the size of the floating solar system, will give an indication of total water saved.  As an example:

  1. A 10 MW FloatPac Solar system covers approx 105,000m2 or water surface area.
  2. Conservatively estimating 600 litres of water saved per square metre per annum, this equates to a saving of no less than 63 million litres of water per year through evaporation reduction.

There is also the benefit of water reclamation; Estimates by the Council on Energy, Environment and Water (CEEW) that up to 20,000 litres of water per MW can be reclaimed each routine cleaning session.

On a 10 MW installation (approximately 25,000 panels), that’s a saving of up to 10.4 million litres of water on a weekly cleaning schedule.  Extrapolating this out over a year, this could mean the additional saving of some 540 million litres of water simply by cleaning the floating systems with the water housing the system, which then runs off the system, and back into the water body below it.

 

This represents a potential saving of over 600 million litres of water per annum for a 10 MW FloatPac floating solar system.

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