High-Efficiency Pumping - A Key Ingredient for Emissions and Cost Savings

Recent research from Xylem has revealed significant opportunities for the global wastewater market to substantially cut its electricity-related emissions. Kieran Gagg, Transport Growth Centre Manager Western Region at Xylem, examines some of the areas where savings can be most rapidly achieved.

The drive to reduce energy usage and carbon emissions remains of the utmost importance for all industry sectors, but perhaps never more so than in the wastewater sector which uniquely links the water, climate and sustainability agendas together as one. Despite this many within industry believe that the most easily achieved efficiency steps have already been mastered –wastewater processing remains largely untapped.

In the wastewater sector, greenhouse gas emissions are derived from the energy consumed during the treatment process and from fugitive emissions as a consequence of wastewater decay. Wastewater treatment is itself an energy-intensive process, with emissions levels varying depending on the energy source of the local electricity supply i.e., coal or gas or perhaps renewables. In addition, the nature of the treatment being applied, and the degree and type of pumping required to transport the wastewater around the plant and through the process, can dramatically effect energy consumption and therefore emissions.

In fact, research undertaken by Xylem shows that almost half of all electricity-related emissions, emanating from the global wastewater sector, could be abated at negative cost.

The research by Xylem, covered three regions – Europe, the US and China – and revealed the most significant saving opportunities to be in the areas of wastewater pumping and secondary treatment. These are both areas where electric pumps are widely used, demonstrating the importance of maximising the efficiency of pumping operations.

Perhaps most significantly, the research showed that rather than needing new technologies or an aggressive carbon pricing policy, these savings could be readily achieved through the adoption of existing high-efficiency technologies. While these may in some instances have a higher initial capital cost, the lower ongoing electricity and maintenance costs ultimately results in money saved over the life of the equipment.

One key method used to calculate the savings achievable in each operational area is by examining the marginal abatement cost via a marginal abatement cost curve, or MACC. For the UK and Ireland, a MACC covering all areas of potential energy cost savings shows one area to be head and shoulders above others in terms of saving potential: high-efficiency pumping in secondary treatment. In fact, through the use of high-efficiency, non-clog pumps for in-plant pumping in secondary processing operations, a company is able to save approximately £2,000 for every ton of CO2e abated, depending on the efficiency of the existing technologies in place.

This is an area already recognised by the authorities, with regulations requiring the adoption of high-efficiency pump equipment already taking effect in Europe in the form of the ErP directive. According to the EU Commission, the main target of the eco-design directive, or the EuP Directive as it was more commonly known, was to cut power consumption in half by 2020 - focusing initially on all the products that consumed energy directly.

To date, the target remains the same, but the EuP Directive was superseded in 2009 by a revised edition which also includes products that are related to the use of energy as well as products that consume it directly.

Second on the list for the UK and Ireland, is the introduction of optimal speed pumping in wastewater transportation. This is another area where the generation of emissions is dominated by the use of electrical pumps, creating a great opportunity for savings through the adoption of high-efficiency pumping solutions.

In both of these areas, because savings can be achieved at a negative or at worst neutral cost, adoption of best practice pump selection and usage has the potential to unlock significant energy efficiency enhancements and capital which can be reinvested in other areas such as renewal of water and wastewater pipe networks.

The savings achievable through investment in the most energy-efficient pumps means it makes financial and environmental sense for all wastewater processing companies to embark on a programme to optimise their pump operations. This can become even more attractive if financial incentives are made available – either through central government support or innovative financing packages – to implement these technologies, which may have a higher upfront cost but almost invariably boast lower life cycle costs than most alternatives.

In some cases, where stringent abatement objectives are in place, the use of public sector funding to finance this type of investment can easily be justified when compared with what would be needed to support higher-cost abatement, in other areas of the economy.

What is now needed is for the wastewater sector and policy makers to join forces and overcome existing barriers for the adoption of energy-efficient technologies. A key focus should be placed in the area of pumping where significant savings can be made, while increasing the productivity of wastewater operations and meeting our climate change targets.