Will continue going green in its second century
The National Park Service will celebrate its 100th birthday on Aug. 25, and the NPS is actively preparing for a second century of stewardship and engagement by “going green.”
Your national park has been doing so by installing geothermal heating systems in buildings on Bathhouse Row, using solar panels, recycling cardboard (1,163 pounds in 2015) and other materials, exchanging fluorescent bulbs for LEDs operated by motion sensors, and purchasing an electric vehicle for trash pickup along Bathhouse Row. LED lights consume less than 20 percent of the power and last more than three times as long as the equivalent fluorescent lights being replaced, and they also help to preserve the park’s cultural resources, especially the artifacts and archives of the museum collection that are harmed by exposure to the UV light produced by fluorescent bulbs.
About 10 percent of the electricity used at the park’s maintenance complex comes from solar power, and the park also operates several solar water heaters. The solar array on the roof of the Lamar Bath House, which powers a large air conditioner, created 1.4 kilowatts per hour (kWh) in January and 2.2 kWh in February 2016. To put that in perspective, the average household in the U.S. uses about 1.3 kwh. When the park installed geothermal heat in the administration building, the electric bill decreased by nearly $1,000 per month! It takes about 11,000 gallons of water per day to heat the building (less than 2 percent of the daily hot springs’ flow) with a tube and shell heat exchanger system. As thermal water is piped through the tube, circulating “return” loop water is piped through the shell in the opposite direction and is heated by the thermal water before moving back into the coils. There, the newly heated water warms air forced over the coils which then heats the building. Sustainability of the thermal water is more to the park than “going green” — it’s the core mission. While the hot springs provide a means to reduce carbon emissions via reduced electricity use, the park must provide the means to preserve both thermal water quality and quantity. This is becoming increasingly important in the face of changing weather patterns that bring intense rain events and rising air temperatures because the ultimate impact on the hot springs remains unknown.
It is a common misunderstanding that the hot springs are heated by
a volcanic process, but there is no volcano here. Instead, the water that falls as precipitation nearby seeps deep into the earth and is heated by the warm rocks along the geothermal gradient over thousands of years. “Geothermal gradient” is a term used to describe how the rock layers making up the crust of the earth get warmer the farther from the surface they are. Recent research indicates that the hot springs’ water reaches a maximum depth of about 6,500 to 8,000 feet below the surface and a maximum temperature around 150 degrees Fahrenheit. Rock doesn’t start to turn into magma until around 1,300 degrees Fahrenheit!
Changing weather conditions may not have much impact 6,500-plus feet down, but there must be water entering the system to have flow out of the system. If changing climates result in increased runoff and more evaporation, the amount of water entering the area known as the “recharge zone” could decrease and the amount of water coming to the surface in the “discharge zone” could also decrease. Current research is ongoing to help determine what impacts may occur with projected climate conditions.
If lower flow rates do occur, the park expects to see decreased water quality as a result. As the thermal water emerges from its depths it mixes with shallower, cold groundwater. This water tends to have more contamination from the surface, and if hot spring flows decrease, this shallower, cold groundwater will have more influence by having more time to mix with the deeper thermal waters. Exactly how much and what kind of contamination and to what degree average temperatures of the thermal springs may decrease because of this mixing is unknown. In the face of such uncertainty, it is important to remember that individual and collective action can make a difference. “Going green” reduces carbon emissions which ultimately will help stabilize global climates. Join your national park to make it happen and help protect the health of your unique natural resource — the hot springs.
This month’s Ask Liz was contributed by Shelley Todd, Natural Resource program manager of the National Park Service.