Nobody likes to think about toilet paper after it has “done its job”, but thankfully chemists at the University of Amsterdam (UvA) have done the dirty work, only to discover it's not receiving the credit it's due. We don’t treat waste toilet paper very nicely, yet it’s still a rich and free source of carbon. Those in Western Europe flush up to 14 kilograms (30 pounds) of this stuff down the drain every single year (Americans flush even more). So could it have any worthwhile value as an energy source?
As explained in the journal Energy Technology, the team of researchers from UvA developed a theoretical way of converting waste toilet paper into electricity through a relatively simple two-step process. Using their model, they believe it is possible to power 6,400 homes a year using Amsterdam’s yearly usage of toilet roll (which is around 10,000 tons, by the way).
Toilet paper is just a sheet of 80 percent cellulose straight from a tree, so the energy is effectively renewable. What’s more, it’s totally free and consumers could, in theory, actually be paid to have it taken off them. Paid to poop, in effect.
The process converts the organic carbonaceous materials of toilet paper into carbon monoxide, hydrogen, and carbon dioxide. Then, high-temperature solid oxide fuel cells are used to directly convert the gas into electricity.
The overall electric efficiency of this process could be around 57 percent, which is similar to a natural gas combined cycle plant. The cost of electricity would be approximately ¢20.3/kWh, which is about the same as current residential solar-panel installations.
“When we discuss these results with companies, people get very excited," said Professor Gadi Rothenberg from the UvA in a statement.
Of course, for now, this is all pie in the sky dreaming. However, the research team hope their model could be used elsewhere outside of the Netherlands. While the capital costs are still fairly high due to fuel cell costs, this would decrease over time as the market expands.
“We might see the first WTP-to-electricity plant being built in China," added Rothenberg.