Global emissions of carbon dioxide (CO2) have increased by almost 50 percent since 1990 and, as many countries enact legislation to decrease CO2 emissions, there is growing pressure on municipalities and governments to show leadership in addressing global warming. Improving energy efficiency is a key tool for reducing CO2 emissions, along with energy conservation and the adoption of low-carbon energy sources such as renewables.
With pumping systems across all industries and applications accounting for almost 20 percent of the world’s electrical energy demand, pump efficiency is not only a business priority, it is a moral imperative. Ensuring optimum efficiency in water and wastewater pumping systems will support the drive to meet global emissions reduction targets, while also delivering considerable cost-savings for pump users.
A focus on efficiency
As operators seek to reduce operational costs and achieve regulatory compliance in response to new energy efficiency standards, demand for high-efficiency pumping systems is growing. This is coupled with a shift in focus from the energy efficiency of single components or products, to optimizing efficiency throughout an entire system with the correct combination of components, resulting in reduced carbon emissions and lower life-cycle costs. Maintaining high energy efficiency over time is a major concern with solids-handling pumps in particular.
Many factors affect the energy consumption of a pumping system: the total head, the overall efficiency of the pump (drives, motors and hydraulics), and the ability to sustain efficiency over time. A common issue which leads to sub-par efficiency is the incorrect sizing of products to compensate for the maximum load. This puts undue stress on the system and leads to inefficiency, costing money and creating potential issues within the system.
Understanding life-cycle costs of the pumping system
When investing in a pumping system, there is a tendency to focus on the initial capital investment at the expense of other factors that could dramatically reduce running costs and improve performance. While increasing the energy efficiency of a pump requires capital expenditure, this initial outlay is typically repaid within a short period in the form of reduced energy costs. In fact, the purchase price of pumps is typically less than 10 percent of the life-cycle costs.
A Life Cycle Cost (LCC) calculation can serve as a valuable tool to better understand the total costs over the product’s life time, providing a clear view of the energy consumption and thus, the CO2 emissions. Understanding life-cycle costs can also help to motivate a higher initial investment by showing how quickly return on investment will be delivered. As such, LCC analysis has a crucial role to play in helping municipalities and governments effectively select technologies that will support the drive for lower emissions.
Ensuring sustained efficiency in wastewater pumps
Sustained efficiency is defined as a pump’s ability to maintain its initial efficiency over time, when operating in the intended application. Currently, wastewater customers who buy and operate non-clog pumps believe the pump efficiency will match what has been stated in the manufacturer’s documentation. However, clean water pumps and wastewater pumps are both tested for efficiency using clean water. Pump performance is recorded as clean water performance. The reality is that non-clog pumps have vastly varying applications that immediately challenge pump performance. The type and volume of soft solids being transported impacts the performance of the pump, and the measure of actual efficiency may vary widely from factory-tested efficiency.
This means that operators are often unaware of the actual efficiency they are getting from their pump. Sustained efficiency is expected, but often not delivered. Specialized laboratory non-clog pump tests and extensive measurements in the field have shown that end user’s actual energy costs are typically increased by as much as 20-30 percent for on-off pump operation, and often more for pumps with long duty cycles or those in continuous-duty operation.
Optimizing pump efficiency from the start
Achieving optimum efficiency in the pumping system is contingent on ensuring that the system is accurately programed for the most common flow rate. A common error is to optimize the pump for the specified maximum inflow rate – which often varies significantly between normal and peak flows. The result is that the pump is oversized relative to the most common incoming flow, increasing energy consumption and the cost of pumping.
The solution is to select a pump that can manage the maximum flow and head but also matches the best efficiency point with the most frequent flow conditions. Fluctuating inflow rates can be addressed either by using multiple pumps, or by using pumps of different sizes within a pump station.
For wastewater pumping applications, the station design is of major importance to decrease clogging and buildup of debris. By using a pump station design tool, it is possible to achieve optimum inflow conditions to the pump and maximize energy efficiency, while also lowering the footprint and investment cost considerably.
A new level of thinking in pump technology
Pump technology is becoming smarter and moving toward greater efficiency. At Xylem, we hear from customers every day who are seeking to maximize the energy efficiency and enhance the life-cycle costs of their operations. Increasingly, they also want solutions that will help them extract actionable insights from data to optimize their operations. We are investing to help customers address these challenges.
For wastewater applications, for example, Xylem’s Flygt Concertor, is a world-first intelligent wastewater pumping system which has been shown to deliver energy savings of up to 70 percent compared to a conventional pumping system. The system design combines IE4 motor efficiency, N-hydraulics, integrated power electronics and intelligent controls. All these features are designed to work in harmony with each other, which results in optimal pumping performance at the lowest cost of ownership.
Before its official launch on the market, Flygt Concertor was trialed in several applications around the world with impressive results. At a pump station located in St. Tammany Parish, Louisiana, energy savings of $1,000 per month were achieved due to reduced power consumption during off peak periods. At London’s Heathrow Airport – the UK’s busiest airport – energy consumption was reduced by 53 percent at one pumping station where chronic clogging issues were a significant challenge.
Advancements in pump efficiency are not limited to wastewater pumps; breakthroughs in clean water pumping technologies also continue to set new benchmarks in efficiency. For optimum efficiency in water supply and HVAC applications in commercial buildings, for example, Xylem’s Lowara Smart Pump range is equipped with built-in ultra-premium efficiency IE5 motors – delivering the highest level of performance and exceeding current IE3 legislative requirements. Featuring advanced variable speed drives, the next generation Lowara range lays the foundation for achieving the highest efficiencies, classified as IES2 standard.
The benefits of efficiency improvements in pumping systems are many, from operational efficiency and reliability, to lower operational costs and environmental advantages due to reduced carbon emissions. At Xylem, we look forward to continuing to support customers in the drive for true operational efficiency while also doing our part to advance vital work to address climate change.
Tomas Brannemo, president of Xylem’s transport business