The U.S. power sector has entered a period of transformation, and water and wastewater utilities are responding by examining and addressing how these changes are impacting costs, reliability and resiliency. In recent years, federal environmental regulators have gently pressed the nation’s energy-intensive water and wastewater sites to lead the charge in energy efficiency, starting with a comprehensive strategy to make that happen.
Yet even as immense opportunities for greater sustainability and resiliency abound through rethinking energy use, many utilities remain on the sidelines in this potential game-changing nexus of water and power.
In an industry replete with aging infrastructure and a mindset of doing more with less, water and wastewater treatment sites are traditionally among a community’s biggest users of energy, given the pumps, motors and other equipment that run around the clock.
However, a survey for Black & Veatch’s 2018 Strategic Directions: Water Report shows that only a little more than one-third of respondents have an actual foundational energy master plan. And even then, half of those respondents said their plan could not be considered comprehensive. An additional 30 percent were not sure if they had any energy master guide, while another one in four respondents said piecing together such a plan together was not in the works (Figure 1). In both of those respects, the takeaway may be the lack of recognition of the significant energy impacts in the water industry.
Figure 1: Does your utility have an energy master plan?
Still, according to the survey, many in the water sector are taking steps to control electricity costs, with nearly one of every three respondents saying they either have made capital investments in power efficiency upgrades in the past three years, or they have partnered with a local electric utility on demand-response programs. Such investments may include installing more efficient pumps, aerators and blowers. Less than 10 percent of respondents, however, said they were considering new or additional on-site power generation (Figure 2).
Figure 2: What is your utility currently doing to manage electricity usage costs?
Diesel engines overwhelmingly prevail as the backup electricity source that water and water treatment plants have at the ready for critical generation if power disruptions hit, typically because of severe, violent weather events or even earthquakes, but such backup generation is only temporary.
Some water utilities are turning to solar power, and facilities with limited land space for solar installations are adopting innovative solutions.
In 2017, Hong Kong’s government hired Black & Veatch to examine the feasibility of floating solar farms across 17 impounded reservoirs. By turning to Black & Veatch, an integral player in development of Hong Kong’s water supply since 1930, Hong Kong hopes to curb evaporation-related water loss while quelling algae growth and, of course, generating renewable power. Studies so far have shown the arrays do not observably affect water quality or wildlife. Similar tests of floating solar are under way elsewhere in Asia.
Water and wastewater utilities typically are less familiar with the concept of a microgrid than other major utilities. Microgrids hold the promise of greater resilience through reliable service when catastrophic events lead to extended loss of grid power, although the 2018 Strategic Directions: Water Report survey again suggests that water providers are not seizing on that potential. A sliver of respondents — just six percent — said they have considered microgrids only for their sites, while three percent have pondered it both for their facility and as a community benefit (Figure 3).
Figure 3: Has your utility considered microgrids for resilience and revenue generation?
An overwhelming three-quarters of the respondents did not consider microgrids relevant to their operations, or the respondents did not know whether that option had been considered or was applicable. Reasons for such inaction vary from a preoccupation with tending to key processes and the plant’s core operations to a complacency or reticence about investing in anything ancillary to their distribution, collection or treatment systems.
On the energy recovery side, opportunities also are legion through such options as collecting and cleaning biogas recovered during the waste digestion process or power generation from effluent water flows. Biogas can be used to generate power using on-site engines, or it can be injected as a renewable natural gas into existing pipelines. These processes create energy through feedstocks that are constantly available at a wastewater plant. Effluent wastewater flows can be harnessed to generate electricity for behind-the-meter supply, providing added value from what would otherwise constitute an expense side byproduct.
As the nexus of water and power becomes more deeply seated and defined, it is time for water utilities to address their energy usage patterns and costs and to scrutinize their resiliency and sustainability, perhaps beginning with an energy audit that gives a granular look at their power use and portfolio capabilities. More forward thinking influencers are needed in the water utilities industry and municipal operations to systematically engage decision-makers, step beyond convention and hasten change by exploiting technology that cuts costs while generating revenue with on-site assets.