Emissions & Water Usage

Reduction of Emissions from Coal-Fired Electricity

San Juan Generating Station is required to comply with a federal regional haze or visibility rule. PNM participated in discussions that led to a Feb. 15, 2013 agreement between the N.M. Environment Department and the U.S. Environmental Protection Agency. The agreement would lead to the retirement of two of the four coal-fired electricity generating units at the power plant by the end of 2017 and the installation of a nitrogen oxide-reducing technology known as selective non-catalytic reduction on the remaining two units by early 2016.

The plan reduces nitrogen oxides along with sulfur dioxide and particulates (all related to visibility impact) and a number of other emissions, including a significant reduction in greenhouse gas and the amount of water needed for generation:

Emission % Reduction
Nitrogen Oxide 62
Sulfur Dioxide 67
Particulate Matter 50
Mercury 50
Carbon Monoxide 44
Volatile Organic Compounds 51
Carbon Dioxide 50
Coal Ash Produced 48
Estimated Water Usage 50

 

The agreement is not final and must go through a lengthy approval process. In Sept. 2013, the N.M. Environmental Improvement Board unanimously approved the plan, which was submitted to the EPA where consideration will take about a year. The N.M. Public Regulation Commission also must approve components of the plan, including the replacement power and cost recovery.

PNM modeling shows that the most cost-effective resource mix to replace two retiring units at San Juan Generating Station includes nuclear (from an existing nuclear plant, the Palo Verde Generating Station), a new natural gas plant (2018) and 40 megawatts of solar PV mounted on single axis tracking.

2009 Environmental Upgrade

In 2009, PNM completed a four-year $320 million environmental upgrade San Juan Generating Station.  The upgrade significantly reduces emissions including:

  • nitrogen oxides
  • sulfur dioxide
  • particulate matter
  • mercury

Because of the upgrade, the plant is in full compliance with the federal mercury rule issued in 2012.

The Connection Between Energy and Water is Significant

On the PNM grid, it takes almost ½ gallon of water to produce one kilowatt hour of electricity. PNM makes continuous efforts to save water use on its system. Since 2002, PNM has reduced the amount of water used to create a kilowatt hour by 22 percent through the addition of new resources and continuous conservation efforts at existing power sources.

Although less than two percent of water withdrawals in New Mexico are used for producing electricity, a significant amount of water is used at power plants for cooling. Electricity generation uses water, whether the power comes from hydroelectricity, coal, natural gas, nuclear, biofuels and even concentrated solar. The gathering, purification and distribution of water also uses a significant amount of energy, especially in the West where water is sometimes piped hundreds of miles to its destination.

PNM residential customers use an average of 600 kWh a month. That's 300 gallons per month that each customer uses, even though they never see it and most certainly never think about it. To put that into perspective, the per capita water use in Albuquerque is around 150 gallons per day. In other words, it takes 15 times as much water for our household water use (per person) than it takes to generate the electricity for that entire household.

Still, there is a direct link between water used in our homes and water used at the power plants, so every effort to conserve water on both fronts is very important to sustained economic development and quality of life in New Mexico.

Since 2002, PNM has reduced the amount of water used to create a kWh by 22 percent through theaddition of new resources and continuous conservation efforts at existing power sources: 

New Resources

  • Increased use of renewable energy.  At the end of 2013, PNM had enough wind and solar to power the equivalent of 81,892 homes, with more on the way.  Except for some minor water use during construction, these wind and solar resources do not use any water for their daily operations.

Efficiency

  • Successful implementation of energy efficiency programs since 2007. Our customers have saved more than 300 million kWh with PNM energy efficiency programs, with an equivalent of more than 113 million gallons of water saved.

Existing Resources

  • Gray water use from the City of Deming at Luna Energy Facility in Deming reduces freshwater use by one-third.
  • Use of gray water from the City of Phoenix (and other nearby communities) for all cooling purposes at the Palo Verde Nuclear Generating Station.
  • Parallel cooling at the Afton Generating Station saves 40 to 70 percent of freshwater consumption depending upon operating conditions.
  • Water conservation efforts at the San Juan Generating Station including cooling towers that condense the turbine-turning steam back into water so it can be reused. Through a series of complex processes, water is reused at least 10 to 15 times. In some plant processes, water is reused as many as 50 to 100 times before it is ultimately evaporated.
  • Completion of an extensive water use study at San Juan that identifies in further detail how water is used in the plant and opportunities to increase water efficiency.
  • A proposed shutdown of two coal-fired electricity generating units at San Juan Generating Station by the end of 2017 will result in cutting fresh water consumption almost in half.