Power Plant Water Management
Use of Produced Water in Recirculated Cooling Systems at Power Generating Facilities - EPRI
The objective of this project is evaluation and development of the use of produced water from oil and gas fields to replace raw water currently used in recirculating cooling systems in power generation facilities. The techniques and information developed are applicable to any project where produced water or mine drainage is being considered for cooling system use. The location of this project is the oil and gas fields and power generators associated with the San Juan River Valley in Northwestern New Mexico. New Mexico is the sixth largest producer of oil and gas in the United States and also has one of the lowest annual rainfalls. The pressures of growing populations, increased agriculture, new business development, and interstate water compacts have put increasing demands on raw water in all of its river basins. Oil and gas production generates wastewater, up to seven or eight barrels for every barrel of oil in the San Juan basin. At the same time, the need for further energy sources has caused oil and gas producers in the state to infill existing well fields and increase the pumping of water to enhance production. Produced water must then be transported to injection wells by truck or pipeline and treated before injection into brine aquifers. While this water may not be suitable for many purposes, it may be possible to treat the water for use as make-up water to re-circulating cooling systems in power generating stations.
The San Juan River Basin provides an ideal test case for this project, since there is sufficient produced water to provide up to 20-25% of the cooling water requirements of the 1800 MW San Juan Generating Station operated by Public Service of New Mexico (PNM). This water source may become critical to their operation at full loads (without de-rates) in future drought years, since New Mexico has been unable to recharge reservoirs during the past few high-rainfall years. While the wells in these fields are widely spaced, and the produced water is generally trucked to satellite injection wells, the water quality and proximity to the generating station are good enough to warrant further investigation. If the concept proves to be economical in this region, it is likely to be more easily adapted to other regions, such as the southern San Joaquin Valley in California, where well spacing is closer and piping infrastructure for produced water already exists.
The project begins with the evaluation of the produced water quality, quantity, and location. Each is critical to the potential use as cooling water for the following reasons:
- The quality of the water determines if the water can be economically treated to meet cooling system standards based upon metallurgy and operations of the plant. In addition, this analysis is used to determine wastewater treatment and disposal requirements.
- The quantity of produced water available determines the economics of the project, how much raw water can be offset, and required infrastructure to deliver and use it.
- The location of the produced water determines infrastructure and cost to collect and transport the water in sufficient quantities to provide favorable project economics.
Existing produced water collection, transportation, and treatment systems are evaluated for possible use in developing the new resource. Any existing infrastructure is evaluated for potential conversion and availability for delivering cooling water to the generating station. Station systems and operations are also assessed for necessary changes to use this resource.
After all of these data are collected, the technical experts assess treatment options with an exhaustive costs/benefits analysis of the proposed optimal system. If new water treatment technologies show promise of technical or economic benefit, they are evaluated. Bench and pilot testing of the treatment options is implemented as required for a proof of concept.
With the data from the cost/benefit analysis, the project team determines the feasibility of implementing such a program, including an analysis of required permitting, proposed contractual arrangements, and intangible benefits. The findings of the project are presented in a comprehensive report that is generally applicable to energy producers and electric power generators in evaluating similar water conservation programs in other areas.