Reducing the energy-intensity of water and waste water distribution and treatment

Transcription

1 Reducing the energy-intensity of water and waste water distribution and treatment Bay Planning Coalition: Energy & Water Nexus Summit, September 5 th, 2014 Dr. Peter Williams, CTO, Big Green Innovations, IBM

2 Energy-in-Water! Moving and treating water in the US uses >100 million mwh of electricity per year - 3-4% of the national total More in some areas than others, depending on geography, urbanization, water source, water content, technologies used On the fresh water side, pumping is 95% of the total Usually a water utility s biggest or second biggest expense. Often the biggest energy user in entire cities.! (Natural gas may also be used at treatment plants).! A natural focus for conservation! But several factors promoting increased energy intensity: Growing urbanization Falling ground water levels New treatment standards and technologies (UV, RO filtration for desalination), Need for new sources requiring new technologies as above

3 The energy management tool kit today...! Source selection! Pump selection! Pump maintenance! Well maintenance! (Conservation AMI, other)! Use of grey water! (Treatment methods)! De-sal methods! UV! Use of available ecosystem services! VFDs! Pressure management! Pump selection and optimization! Pump maintenance! Leak detection! Pipe renewal hydraulic losses! In-conduit hydro Extract Treat Distribute (Use) Collect Waste- Treat Discharge Recycle! (Pump management)! (Treatment methods & levels )! Use of available ecosystem services! Blower and aerator mgmt! Dynamic DOC mgmt! Energy recovery heat, methane, bio-plastics, nitrogen! (Pump management)! (As for Treat )! Predictive maintenance! Motor replacement! Capacity management! Equipment right sizing! Land use eg for solar

4 Some of the known savings from these tools are non-trivial! VFDs where suitable, 5-50% of the energy use of each pump in question.! Pump maintenance especially interior surfaces up to 5-18% per pump.! Pressure management 5-10%.! Dynamic pump optimization (includes pressure management) 6-20% system wide.! Leak management for a fully pumped supply, equal to leakage rate (US national average leak rate is 14-20%).! More efficient motors 5-30% of energy use of each motor.! Energy recovery: 3,500kwh/day for a 10 MGD anaerobic digestion process; Can be enough to take treatment plants off the grid altogether.! In conduit hydro up to 1.3MW from waste water discharge pipes; 2MW from freshwater systems.! Other possibilities : Blower and aerator management? Right-sizing equipment? Predictive maintenance: ~20%-50% of lifecycle cost of each asset, of which energy savings may be a large component?

5 Future options demand response?! Load shifting bring pumping or aeration activity forward, or delaying it, within constraints set by water agency. Creates a virtual power-station or maximizes reuse of renewable energy for useful work. May be 26GW of process flexibility in the US, of which water agencies are a large part. Also datacenters, HVAC, cold stores and others! Great interest in load shifting to help balance variability of solar and wind power.! Up to 500kw modeled for a 50mgd WWTP! Controls 7MW in US and Canadian water systems today. Demonstrated 400kw for Pennsylvanian American Water from just two pumps.! Raises revenue for the agency: $35-$50k per mw year.! United Utilities (UK) serves 7m people in NW England! Will be offering 10 mw within 12 months, rising to 50mw of load across total asset base. Generating $5m per year in revenue.! Directly predicated on need to balance wind energy UK is a major user.

6 Future options land use for solar?! Solar is increasingly frequent on water agency land and sometimes enough to make treatment plants energy independent.! But how about over the CA aqueduct? 700 miles of canal, of which 444 are open; Estimated 9,600 mwh per day of energy potential; Water helps cool panels so increases potential further. Some reduction in evaporative losses.! Photos are from a Sun-Edison project in Gujarat, India

7 But the tools are often not used Why not? Financial (revenue, capital) constraints? Legacy system constraints? Reliability issues for newer, less energy intensive equipment? No data on energy usage bills paid by other departments? Price of water does not justify changes/ diminishes RoI? Risk mgmt: protection of operating margin (overpressurization, overtreatment)? Incomplete view of cost savings energy, reduced wear and tear, maintenance costs? Not as important as water quality? Regulatory constraints? Lack of awareness of the issue and potential? Staffing levels, skills levels, adaptability levels? Distrust of or resistance to automation??

8 References:! Throughout:! Slide 2:! Slide 4:! Slide 5:! Slide 6: Energy-Water Nexus: Amount of Energy needed to supply, use ad treat water is location specific and can be reduced by certain technologies and responses: GAO, GAO , March Available from Energy Demands on Water Resources Report to Congress on the Interdependency of Energy and Water, Sandia Labs, US Department of Energy, December Available from: EPRI statistics quoted in Greenhouse Gas Reduction as an Additional Benefit of Optimal Pump Scheduling for Water Utilities, S Bunn, Available from: Pumps as Turbines and Induction Motors as Generators for Energy Recovery in Water Supply Systems, AA Williams, NPA Smith, C Bird and M Howard, Water and Environment Journal, Vol 12, Issue 3, pp , 1998 Bunn, op cit European Commission, Study on improving the energy efficiency of pumps, February 2001, AEAT-6559/ v 5.1, quoted in L Reynolds and S. Bunn, Reducing Energy Demand in Water Supply through Real-Time Scheduling and Operation paper delivered to Aqua Enviro Conference, Birmingham, England, March