Weighing The Options

Passive thermal solar systems produce no air emissions, and installations typically utilize the existing circulation pump to discharge water through a series of solar collectors, where a transfer of heat from the sun to the pool water occurs. Downstream of the pool filtration system, a bypass piping system routes the water into solar collectors. If the solar system provides the necessary set-point water temperature, the heater is not activated, thus reducing run time and cost for natural gas.

Non-metallic (polypropylene or EPDM) solar panels are preferred and are less expensive than the copper and glazed variety. Installation costs for this type of passive solar system (assuming suitable mounting space with proper solar orientation) run approximately $12 to $18 per square foot of solar panel. The amount of solar panel required varies by region, but an average of 80 percent of water-surface area is common. With a potential annual operating cost savings of $50,000 to $75,000 (for a 50-meter pool), and an expected full return on investment within four to six years, passive solar systems are highly attractive.

Co-Generation With Micro Turbines

Co-generation implies multiple sources of energy from a single device. For gas-powered micro turbines, recoverable electricity and heat are produced.

Gas-powered micro turbines range from 25 kW-500 kW (based upon anticipated demand). These units produce substantially greater electricity than heat. Sizing for electrical demand means that net-metering (excess generated electrical power sold back to the utility) is usually not feasible unless a renewable energy source, such as landfill or biogas, is utilized. Where heat recovery is used, these systems can be 85 percent efficient, with costs $0.005-$0.016 per kW, and maintenance intervals of 5,000 to 8,000 hours.

These systems also enjoy low NOx emissions (< 9 to 50 ppm) and rebates from utility providers. A 60 kW unit with heat recovery costs approximately $100,000 with payback within 2.5 to 3.5 years.

Co-Generation With Fuel Cells

With co-generation’s use of fuel-cell technology, electricity is generated and heat is recovered. These systems use natural gas for fuel, which is reformed into a steady stream of input hydrogen. Fuel cells are reliable, quiet and virtually pollution free. Economic advantages depend on utility rates, possible rebates and incentives.

Capital costs remain high: $1.1 to $1.2 million for systems of 200 to 250 kW power output, with payback within eight to 12 years.

Photovoltaic Electricity Generation

Photovoltaic (PV) systems convert sunlight into electricity, but no heat is generated in the process. They are simple, reliable, quiet and nonpolluting, with no moving parts.

Capital costs average $7 to $10/watt for standard, flat-mounted roof systems, which can add up to $250,000 for a 50-kW PV system–assuming rebates and incentives. Payback can be up to 40 years. Because natural gas is the largest utility cost, PV systems are less desirable than other efficiencies.

Fluctuating costs will require either scaled-back operations or adoption of energy-efficient pool-design strategies. Pool operators should embrace these technologies, recognizing that while initial capital costs may be high, the technologies can provide a worthwhile return on investment.

Randy Mendioroz is a Principal with Aquatic Design Group, a Carlsbad, Calif., consulting firm that specializes in the programming, planning, design and engineering of competitive, recreation and leisure-based aquatic facilities.

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