Commuter bus runs on human waste
On November 20, 2014, tourists boarded a bus at the Bristol Airport bound for the city of Bath, England. The markings on the bus, however, might have tipped them off that something was different: One side of the vehicle depicted people dumping food scraps into food-recycling bins (standard waste-disposal in the United Kingdom), while the other side displayed a row of citizens perched atop toilets.
The vehicle was the Bio-Bus, the first in the U.K. powered by fuel derived from sewage and food waste. Built by biogas plant GENeco, a subsidiary of the water department, the bus can run for about 186 miles on a single tank of fuel, which is derived from the annual sewage and food waste of five people.
Locally, its a big step towards sustainable, low-pollution transportation. Gas powered vehicles have an important role to play in improving air quality in U.K. cities, but the Bio-Bus goes further than that and is actually powered by people living in the local area, including quite possibly those on the bus itself, GENeco general manager Mohammed Saddiq said. Using bio[gas] in this way not only provides a sustainable fuel, but also reduces our reliance on traditional fossil fuels.
Despite the unappealing origins of its power source, the bus is a breath of fresh air. According to a report in Fast Company, nixing the diesel fuel cuts pollutants by 97 percent. GENeco also claims that, compared to diesel buses, the Bio-Bus emits 20 to 30 percent less carbon dioxide, contributing less to climate change.
In addition to refueling the Bio-Bus, the GENeco biogas plant pumps enough electricity into the grid to power 8,500 homes.
Biogas is created through anaerobic digestion. In an oxygen-less tank, called a digester, microorganisms break down organic material. The process nets two products: biogas (methane and carbon dioxide) and fibrous byproducts that are repurposed into things like animal bedding and fertilizers. Methane then passes through a process that concentrates it to the levels necessary to replace fuel or to power the electrical grid.
This process uses diverse waste sources. Biogas can be rendered from landfills, wastewater, manure, and agricultural waste (think stripped sugar cane), among other sources. The GENeco plant converts more than 2.6 billion cubic feet of sewage and upwards of 38,000 tons of food waste. Its the first and largest plant in the U.K. to use food waste and sewage to deliver energy to the grid.
If implemented worldwide, biogas would create a sizable impact. The EPAs National Renewable Energy Laboratory estimates that biogasshould it be gathered from all available U.S. sourcescould offset 46 percent of natural gas consumption for electricity and replace natural gas in transportation entirely. In fact, if all sources were tapped, it would produce the biogas equivalent of 35 billion gallons of gasoline. There are currently more than 1,500 biogas digesters at wastewater treatment centers in the U.S.. Some produce enough electricity to go entirely off-grid.
Using biogas for transportation is still new. Several similar projects, however, have sprung up across Europe in the past several years, spurred by aggressive renewable-energy legislation. Sweden, for instance, runs a fleet of more than 36,000 vehicles, including trucks and buses, using waste-derived biogas. And Oslo, Norway, has about 80 poo-powered buses on the road.
In 2010, GENeco debuted a proof-of-concept for sewage-derived transportation, the Bio-Bug, before taking on the larger task of revamping public transit. The Bath Bus Company, whose route the Bio-Bus currently follows, also runs tour buses in U.K. destinations, but hasnt committed to using more Bio-Buses.
Critical thinking challenge: How do you think U.S. consumers would react to public transportation fueled by human waste?