New Energy-Saving Valve Technology Boosts Power Conservation in Water and Wastewater Systems
The bad news: Water and wastewater system operators are forecasting continued short-term volatility in energy pricing and much higher prices in the long term. Even more critical, peak-load power pricing hits systems hard, just when their flow demand is high.
The good news: Valve selection and configuration plays a surprisingly important role in a system’s energy consumption. In addition, advanced valve technologies allow operators to save energy costs even more.
Pumping stations consume excess energy in two basic ways:
1. Inefficient valves cause pumps to work harder than necessary, consuming more power.
2. Systems pay for power to pump non-revenue water where water loss could be reduced.
In search of energy savings, engineers rightly focus on the system elements that directly consume power, such as pumps.
However, a careful analysis shows that the valves’ effect on energy consumption is also critical. That’s because the valves determine pressure and flow rates, which in turn impact how much power the pumps require to move the flow.
When you add peak-load power pricing into the analysis, valves can be configured to optimize energy costs as well as flow rates. So, valve selection offers new opportunities in your pursuit of energy savings.
It all starts with reviewing the common flow coefficients for various valves used in pumping stations, as shown in this table (Enlarge table).
This example is a 12-inch valve with a 20-year life. On this chart, Cv represents the flow through a valve with a 1 psi pressure drop, and we see that an energy-saving ball valve offers the best headloss characteristics.
The headloss from valves can be converted into the energy cost related to the pumping electrical power needed to overcome the additional headloss from the valve. (Here’s the equation.)
Cost / Benefit Varies Among Valves
Valve types vary widely in their energy conservation ability. The next chart (enlarge chart) shows that Val-Matic’s new EnerG AWWA Valve dramatically reduces energy consumption compared to other valve options in the example.
Conservation comes with a price in the higher cost of the energy-saving valve compared to old technology. The question is whether the benefit is worth the cost for a given system application.
“We’re excited about the potential energy savings of these new valves,” says Fred Haines of Harper Haines Fluid Control, “but we don’t recommend that water systems use them everywhere.”
Break-Even Analysis by Application
Careful break-even analysis is required to compare the costs with the benefits. Key variables include the size of the system and flow velocities. The analysis should also consider a range of energy pricing scenarios, including peak-load pricing. Break-even analysis on equipment that has a 20-year life will likely include an escalating energy pricing forecast over the life of the investment.
Harper assists clients in quantifying the cost savings of switching to energy-saving valves. “We’ll walk through the design with you, looking at physical layout, pump curves, pump configuration, horsepower, flow ranges, energy costs per kilowatt hour – all the key variables,” said Haines.
Pressure Management to Save Energy
Lower pressure systems reduce energy consumption, both directly and indirectly:
- Direct: Less energy is required to produce and pump water during low-pressure periods, timed to match low demand.
- Indirect: Less water is lost through leaks and pipe breaks. As a result, the system saves energy consumption by producing and pumping less non-revenue water.
Cla-Val’s advanced pressure management control valve allows water systems to manage energy costs more efficiently. (See Graph here.)
Haines suggests that water systems prove it to themselves with metered trials. Harper helps water systems identify locations with good potential for cost-saving pressure management. After a few weeks of experience, the system can calculate the annual costs savings of adding active pressure management through its plant.
Advanced pressure management valves respond immediately to demand spikes, such as may occur during fire flow. (More about advanced pressure management techniques.)
Workshops on Energy Management
Harper International is now offering workshops on the energy-saving opportunities that come with new valve technologies from Val-Matic and Cla-Val. As valve experts, we’re happy to help you analyze and configure the valves in your design.
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Telephone: 203.693.3740 * Fax: 203.547.6092