Austin Water Utility Progress

Cutting greenhouse-gas emissions

Every gallon of water used, treated, and pumped in Austin means energy get consumed – and lots of it. As Austin Energy's biggest single customer, the Austin Water Utility used 1.6% of AE's total deliveries last year. Through aggressive water conservation programs and by making treatment and delivery less energy-intensive, AWU can significantly shrink Austin's greenhouse-gas emissions.

The Austin Climate Protection Program's annual report inventory shows that for 2007, wastewater treatment directly generated emissions of 16,584 CO2-equivalent tonnes. AWU as a whole (indirectly, through electricity use) was responsible for 112,883 CO2-equivalent tonnes. Although the data was omitted from the report, new AWU conservation and process measures through 2008 have reduced annual greenhouse-gas emissions by 5,350 CO2-equivalent tonnes. Future projections, for changes already made or underway, will avoid annual emissions of some 20,000 CO2-equivalent tonnes, through 2017.

Under the environmental direction of Daryl Slusher, for the last two years AWU has increasingly focused on getting water consumption, electricity use, and greenhouse-gas numbers down. Slusher shared a few highlights from a more complete report being finalized, documenting changes in progress.

Process Changes

These improvements are being led by Jane Burazer, AWU's assistant director for treatment, with strong advocacy from AWU Director Greg Meszaros.

Walnut Creek WWTP

Austin Water Utility Progress

In November 2008, the Walnut Creek Wastewater Treatment Plant made a new seasonal process change; one blower is now turned off in winter months. That yields energy savings of 2,500 megawatt hours per year, translating to greenhouse-gas reductions of 1,250 metric tons CO2-equivalent per year, or MTCO2e (see chart). The plant also is fine-tuning controls and improving pump and air-blower efficiencies. When completed in 2010, those changes are expected to reduce electricity use by an additional 2,500 megawatt hours per year and greenhouse-gas emissions by another 1,250 MTCO2e per year. That saves a bundle on AWU's electricity bill. The better to fund new water conservation programs, right?

Ullrich WTP

Austin Water Utility Progress

In 2008, Ullrich Water Treatment Plant staff developed an operations protocol for raw water pumping that minimizes inefficient "throttling." The new process saves approximately 5,000 MWh/year and 2,500 MTCO2e/year.


The planned new Water Treatment Plant No. 4 will draw water from Lake Travis rather than Lake Austin. The higher elevation of the source water translates to less pumping, which means significantly less energy use. AWU has estimated savings on the order of 20,000 MWh and 10,000 MTCO2e per year. By delivering water from WTP4 rather than Davis WTP to the same service areas, AWU estimates greenhouse-gas reductions of 13.5%, from the day the new plant opens in 2014.

Fleet and Equipment

To reduce vehicular trips, AWU Pipeline Operations and Water Conservation field crews are testing the use of wireless communications – laptops used to file reports on-site, thus eliminating the need for many hours weekly of driving back and forth to the office. The suggestion came from field staff. AWU's diesel fleet is now operating on B20. By using biodiesel, AWU staff estimate a net greenhouse-gas emission avoidance of 600 MTCO2e annually. AWU also is testing two television-inspection trucks, switching from diesel engines to noncombustion power units, to supply the electrical needs of on-board equipment with less emissions.

On-Site Energy Generation

AWU is working with Austin Energy on a 115 kW solar photovoltaic array to be installed at Glen Bell Service Center, after the roof is replaced. It is expected to generate about 300 MWh/year and avoid 150 MTCO2e/year.

Water Conservation

The revised city water-use management ordinance that took effect Oct. 1, 2007, implements mandatory watering restrictions year-round for commercial and multifamily users. It also mandates limited outdoor watering days and times for residential customers, from May 1 through Sept. 30. The summer of 2008 was the first under the new mandates, which yielded significant reductions. Slusher cites hard evidence that the program worked: Mondays, previously the biggest water-use days, became a no-watering day under the restrictions; it fell to the lowest water-use day. AWU hopes the numbers will hold and that all customers will get even more serious about conservation this summer. "The toughest test will be a Texas summer where it doesn't rain at all, or hardly at all, in July and August – with temperatures above 95 every day and above 100 on many," said Slusher, noting that Austin had rain every 10-14 days last summer. "We could be looking at that this year."

Making conservation efforts more critical: Global warming itself is projected to increase local water use, according to a study from the Environmental Defense Fund. As warming already underway raises temperatures in Central Texas, landscape and agricultural watering demands can be expected to rise correspondingly, as our climate becomes hotter and drier.

Slusher also noted that AWU conducted more than three times as many irrigation audits in the first two quarters of fiscal year 2009 as during the same period in 2008, and four times as many toilets were replaced.

A new partnership with the city's 311 call center allows 24-hour reporting of water waste; report volume increased 41% immediately following the switch, and 311 allows improved tracking of enforcement and accountability.

City Manager Marc Ott recently asked Assistant City Manager Rudy Garza and Meszaros to step up and improve water conservation results even more; he has challenged AWU to rapidly become as strong a national green leader on water as AE is on electricity.

Customer Energy Use

Slusher said that according to industry estimates, "the energy used by consumers for water heating and on-site pumping [in homes and commercial buildings] may be equal to, or even two-to-three times more than, the energy AWU uses." This "end-use" energy is not reflected in AWU's greenhouse-gas inventory, but AWU wants to see those numbers come down too. It's exploring how to get the message out, as part of its water-conservation and energy-conservation campaigns.

An AE program encourages residential and commercial customers to switch to solar water heaters. It offers rebates of $1,500 to $2,000, plus a federal tax credit is available for $750 to $1,000. A new on-demand water heater also can reduce energy use.

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