|May 16, 2013|
On Mount Everest, Seeking Biogas Energy in a Mountain of Waste
|Nestled in the shadow of the world's tallest mountain, the tiny village of Gorak Shep has a very messy problem.|
The Sherpa community literally is running out of space to put human feces from the Everest, Pomori, Lhoste, and Nupste base camps. Each year, porters haul more than 12 metric tons of excrement down the mountains and dump it into open pits at Gorak Shep. A spring 2012 National Science Foundation (NSF) survey found contamination of one of the two major sources that supply water at Gorak Shep.
A volunteer group of Seattle-based engineers is working on an innovative solution to the problem, one that also will provide a big energy benefit. Earlier this month, they completed a design for a biogas reactor to convert climbers' feces into methane gas to serve as a cooking fuel for the Sherpa villagers. Construction could begin as early as next year. If it is a success, the Mount Everest Biogas Project will be the world's highest-elevation biogas reactor and proof-of-concept for an invaluable tool to protect iconic high-mountain ecosystems.
A Better Tribute
The genesis of the idea was a realization that Seattle climber Garry Porter had shortly after his attempt to summit Everest a decade ago. Porter's small expedition made it to Everest's South Summit, only 120 meters beneath the true summit, before being forced down the mountain due to high wind conditions.
Upon returning to Mount Everest base camp, he watched a steady procession head down the mountain to the village of Gorak Shep below. "I remember seeing a group of Sherpa men carrying these blue barrels of human feces to dump at Gorak Shep," Porter says. "I couldn't shake the feeling that my final tribute to Nepal and the people of Everest was having my waste dumped in these open pits. It just didn't seem right."
Gorak Shep serves as a launching pad and acclimatization stop for many trekkers. But there are no electrical, sanitation, or water-supply systems.
Porter, an engineer who spent 34 years at the Boeing Company before his retirement, contacted his friend and Everest guide Dan Mazur and they agreed to tackle this issue together. Mazur, an organizer for the Mount Everest Foundation for Sustainable Development in Nepal, had previously worked with lowland farmers who used biogas digesters to convert animal dung to methane gas. He suggested a similar system could work at Gorak Shep.
In biogas production, bacteria feed on organic waste (like feces) and produce several gases as a byproduct. One of these is methane, which is the primary component of natural gas and can be burned for heat and light, or converted to electricity. One cubic meter of biogas provides about two kilowatt-hours of useable energy. This is enough to power a 60-watt light bulb for more than a day, or an efficient 15-watt CFL bulb for nearly six days. A biogas reactor at Gorak Shep could address the fecal contamination problem while providing the perennially low-income community with a sustainable source of methane gas for energy, especially for cooking, Porter says.
But the harsh conditions of Mount Everest, which have challenged so many climbers, tested the skills of the engineers.
For starters, air and ground temperatures are below freezing most of the year at Gorak Shep, which sits at an altitude of 5,164 meters (16,942 feet) and briefly served as the first Everest base camp in 1952. Biogas production stops entirely when the temperature hits freezing, says Robert Spurrell, former director of research and development at the Weyerhaeuser Company, who is serving as technical manager for the Everest biogas project. Normally, recirculating water heated by methane gas inside a reactor offsets cold outside temperatures.
However, because the biogas reactor at Gorak Shep will run exclusively on human fecal matter-a poor methane---producing fuel source---this won't be possible. Spurrell explains that organic waste can be divided into two groups: carbon-rich or nitrogen-rich. Animal waste contains a lot of carbon cellulose which gives it a high carbon-to-nitrogen ratio, around 20:1. This promotes methane production. Human waste on the other hand has a low carbon to nitrogen ratio, around 6:1. This makes it a poorer quality fuel source.
"In essence, if we use the methane gas in our system to heat the recirculating water, the energy production will be too low to provide cooking fuel to the villagers," Spurrell says.
To make things even more difficult, all building materials have to make a five-day, rugged journey to the village via pack animal or strapped to a human's back. "It's not like we can go to Lowe's or Home Depot," Spurrell says. "We definitely chose the hardest place on Earth to do this."
The engineering team arrived at a renewable energy solution to the temperature problem. Porter says they will use nine or ten off-the-shelf, 0.8-by-1.2-meter solar panels to heat a large tank of water inside a storage building, built over the underground biogas reactor. A heating coil, running from the water tank to the digester's interior, will provide enough energy to keep temperatures inside the digester around 86°F (30°C). Porter says the 8-cubic-meter digester system, including the storage building and solar panels, will cost approximately $15,000 to $20,000. It could process 16 metric tons of human waste per year, more than the current annual climber load hauled down to Gorak Shep. That amount of waste would produce more than 1,000 cubic meters (35,000 cubic feet) of biogas. That may not seem like an enormous amount of fuel; the average U.S. home that heats with natural gas uses about double that amount in a single winter. But it's an amount that can go a long way in Gorak Shep to serve as a much-needed sustainable alternative fuel for cooking.
Saving Native Vegetation
Sherpa communities in Nepal and alpine conservationists think the Mount Everest Biogas Project could not only solve the fecal contamination problem but also has potential as an alternative to burning fossil fuels and Everest's native plant species. Mingma Tenjing Sherpa, a lifelong resident of Nepal's Khumbu Valley and the project's liaison with the Sherpa community, says an increasing number of foreign visitors are creating an insatiable demand for cooking fuel, campfires, and hot water. This in turn is leading to the overharvesting of Everest's natural resources.
Chief among these is the endangered alpine juniper, a bedrock plant species of high-alpine ecosystems like Sagarmatha National Park where Everest is located. Alpine junipers supply habitat and food for species endemic to the region and prevent soil erosion and desertification. "They grow only a few centimeters every century," explains Thomas Culhane, a National Geographic Explorer and founder of the sustainable energy company Solar Cities. "However, they have been exhaustively harvested for fuel wood since 1962. We are inadvertently destroying local plant species and turning iconic ecosystems like Sagarmatha into high-altitude deserts."
In 2003, two international nongovernmental organizations, the Mountain Institute and the American Alpine Club, began conservation efforts to protect and restore alpine juniper and other cushion plant species. Culhane says the conservationists promoted kerosene as an alternative to burning juniper. The push to replace native plant fuel with kerosene has since resulted in an annual preservation of some 80 tons of shrub juniper in the Everest region alone.
Burning kerosene presents problems of its own, however. The expense and occasional unavailability of kerosene drives both foreigners and locals back to poaching the delicate vegetation, Culhane says. In addition, burning the fossil fuel adds to the atmospheric carbon load; the issue hits home on the mountain, where global warming has caused the retreat of Everest's glaciers.
Culhane says organic waste from the restaurants, lodges, and toilets of new development projects at Everest Base Camp, Gorak Shep, and farther down the mountain, offers an abundant feedstock for biogas.
"There is a commonly held perception that there isn't enough organic material in these mountains for a biogas program," Culhane says. "However, we found that this is simply not the case."
Culhane went to Sagarmatha in spring 2011 to evaluate renewable alternatives to burning fossil fuel. He says the area is no stranger to solar power, thanks to Nepal's 55 percent alternative-energy subsidy. The government support, coupled with the desire of westerners for modern amenities, has led to solar-powered Internet cafes and lodges with hot water, warm meals, and light-up LED signs at nearly every village on the trail to Everest.
But solar alone is not enough to stop juniper harvesting and kerosene burning entirely.
"When the sun isn't shining, you are going to need another source of power," Culhane says. "Biogas could be the answer."