|Solar panels line the roof of the comfort station at Devil's Garden Campground in Arches National Park, Utah.|
The United States National Park Service manages about 84.4 million acres of land in the form of national parks, national monuments, and other historic and conservation properties. While much of the Park Service's holdings are preserved as undeveloped backcountry properties, the NPS provides visitor amenities like lodging, food and other concession services.
The remote locations of many Park Service sites make traditional energy resources expensive and challenging. Ranger stations and campground bathrooms may be located far from the traditional utility electric grid. Diesel generators can be used if road access to the site is possible, but have drawbacks: fuel is expensive, and generators can be loud, produce emissions, and may be out of character for a particular national park site.
In some cases, the Park Service is turning away from traditional energy resources to alternative and distributed energy resources like solar power. In fact, the Park Service has deployed distributed solar photovoltaic generation for over a decade.
Consider the example of Devil's Garden Campground in Arches National Park in Utah. While the campground is relatively remote (located at the end of a 30-mile dead-end road inside the park), Park Service facilities in the campground need electricity. These facilities include two campground hosts, three bathrooms, an amphitheater and a ranger station.
Historically, electricity for the campground facilities came from on-site diesel generators. These units ran 24 hours a day, consuming over 6,400 gallons of fuel per year. Producing electricity from diesel is seldom cost-competitive today; generating electricity from diesel at Devil's Garden Campground cost the National Park Service over $22,400 per year. This meant that the Park Service was generating electricity for a price of 28 cents per kilowatt-hour (kWh), about four times higher than the current average Utah price.
(As expensive as this is, it's still about a third of the cost of diesel-generated electricity on the remote Maine island of Monhegan. In 2010, electricity on Monhegan cost an average of 74.51 cents per kWh.)
As early as 1995, the Park Service joined with the state of Utah to develop four photovoltaic/diesel hybrid systems at Devil's Garden Campground. Each system is composed of a 1.4 kilowatt (kW) tracking array, a 4 kW inverter and a 40 kWh battery bank. Diesel units remain on-site and ready, but now run less than 4 hours per day. This cut the Park Service's annual operation and maintenance costs for the diesel generators from $22,400 to $10,000. The project dramatically reduced the noise level in the campground, and significantly cut the diesels' emissions of carbon dioxide, carbon monoxide, nitrogen oxides, and sulfur oxides.
As this example shows, sites that are already off the grid can be good candidates for small-scale distributed generation projects relying on alternative technologies like solar. Depending on project economics and other objectives (like the Park Service's sustainability initiative, improving noise levels and air quality, or education), replacing diesel with renewable energy -- and making energy efficiency improvements -- can make sense.
Other units in the National Park Service system are following the Arches example by turning to distributed renewable energy and energy efficiency. In 2011, Yosemite National Park installed a 672 kilowatt grid-tied solar array. The $5.8 million Yosemite project is bigger in scale (the Park Service's largest solar energy project) and is tied to the utility electric grid, but represents a similar strategy to that used in Arches and throughout the Park Service.