Friday, October 2, 2015

Coal-Fired Power Intensifies a Heat-Island Over Four Corners


At 775 feet tall, the flue gas stacks at Navajo Generating Plant near Page, Arizona push coal-fired effluent into the upper atmosphere, exacerbating the heat-island over the Four Corners Region - Click for larger image (http://jamesmcgillis.com)

Coal-Fired Power Intensifies a Heat-Island Over Four Corners

Navajo Generating Station (NGS) -

In August 2015, I ate lunch at the Wahweap Overlook to Lake Powell. One year prior, I had visited the same place and eaten lunch while looking out over Lake Powell. This time, I was amazed to see that the Lake level was slightly higher than the previous year. Then I remembered the southwestern monsoon of May 2015. Throughout that month, unusually strong thunderstorms made their way north from the Gulf of California and into the Four Corners region. Even in these drought-stricken times, intense storms appear to turn back the clock on scarcity, quenching both land and lake.

From Wahweap Overlook, the Navajo Generating Station and its 775 foot tall flue stacks seem to fade into the hazy background - Click for larger image (http://jamesmcgillis.com)During my visit, a throng of French-speaking tourists viewed the ethereal sight of so much water in a sandstone desert. None of them seemed to notice the three tall concrete stacks standing in the distance, on the far side of the lake. Although dwarfed by the landscape, each of the three flue gas stacks stands 775 feet tall. At that height, they are among the tallest structures in Arizona. The stacks and the coal-fired power plant that they service comprise the Navajo Generating Station (NGS).

Prior to the installation of new burners in 2009, NGS was the largest emitter of nitrogen oxide in the country. As a greenhouse gas, nitrogen oxide is 300 times more powerful than carbon dioxide. In 2011, NGS emitted 71,000 tons of sulphur dioxide, 14,000 tons of nitrogen oxide and 586 pounds of mercury into the air above Lake Powell and Page, Arizona. As such, NGS remains one of the largest heat and pollution sources in the Four Corners region.

Heat Island Effect -

This 2006 photo of the Grand Canyon shows persistent haze caused by coal-fired power plants in the Four Corners region - Click for larger image (http://jamesmcgillis.com)If you have visited Phoenix, Arizona in the summer, you will be familiar with the term, “heat island”. During the day, pavement and buildings absorb heat from the sun. At night, the convective qualities of dry desert air are insufficient to dissipate the heat of the day. As a result, nighttime often feel as hot as daytime. Only the slow change of seasons brings relief to residents and visitors alike.

Near Lake Powell, the coal fired NGS plays a significant role as a heat generator. Fuel consumed in 2011 provided 170,529,313 Million Btu of heat input. As coal burns in the enormous furnaces at NGS, all of that heat is either absorbed at ground level or sent up the flue gas stacks and into the environment. There, the heated flue gases, still laden with sulfur dioxide, nitrogen oxide, fly ash and heavy metals such as mercury meet the giant methane bubble already in place over the Four Corners region. Picture a gaseous blob of airborne chemicals propelled into the high atmosphere. Effluent from the giant flue stacks of NGS and other coal-fired power plants in the region often punch through the atmospheric inversion layer. Once this heated stream of gas disperses, it creates a persistent regional haze over This 2001 photo shows Lake Powell filled almost to capacity - Click for view of same scene in 2014 (http://jamesmcgillis.com)much of the Southwest.

What are the final consequences of having a highly volatile chemical heat island hovering over the Four Corners region? First, the heat island deflects rainfall away from the area, further exacerbating (perhaps creating) the persistent regional drought. With their rise on a cloud of methane, these greenhouse gases head directly toward the stratosphere, and beyond. Perhaps we need a new “Blue Marble” photo from space, showing the degradation of our atmosphere over the past fifty years.

Four Corners Regional Drought -

This undated Landsat image shows Lake Powell nearly at full capacity - Click for comparative images from 2000 and 2015 - (http://jamesmcgillis.com)For geodetic proof of the Four Corners regional drought, look no further than Google Maps. Most people are familiar with zooming in on a Google map, thus increasing the resolution of small objects. While zooming in on the Wahweap Overlook, I discovered that the midlevel map of the area was a USGS Landsat Map of undetermined age. By zooming in one additional level, I discovered a Google Data map of more current vintage. Click on the thumbnail image of Lake Powell on this page to see a top and bottom comparisons of the two maps.

In the 2015 Google Data map, significant portions of the former lake are now dry land. If not for a new channel cut across it, the former Antelope Island would require the more apt name of “Antelope Peninsula”. Also in the 2015 view, new shoals are visible in each of the first four primary basins, hinting that more dry land will surface in the future. At the upper end of the lake, sediment clogs the river, exacerbating evaporation and producing what scientists call methane volcanoes in the mud.

This is Part 2 of a three-part article. To return to Part 1, please click HERE. To read Part 3, please click HERE.