How toilet paper can power homes in the future
The last thing you want to think about is waste toilet paper. However, the world produces a huge amount of waste toilet paper (WTP): about 10-14 kilograms per person in Western Europe alone.
Waste toilet paper is also a rich source of carbon, with dry WTP containing 70-80 percentage by weight of cellulose. It’s also one of the few waste materials with a negative cost. For example, in the Netherlands, wastewater treatment facilities pay approximately 70 Euros/tonne to get rid of it – making it a very attractive resource as people will pay to get if off your hands.
The cellulose in the WTP comes from trees making the electricity produced truly renewable and can help in matching society’s demand for renewable energy in the future.
All of this makes WTP a resource that can increase resource efficiency and create a true circular economy. It’s for this reason that scientists from the University of Amsterdam used WTP as a resource to generate electricity. The Amsterdam region alone generates 10,000 tonnes of WTP per year, which is enough to power 6400 homes.
The scientists proposed a simple two-step process to convert WTP into electricity enabling a direct route from unwanted waste to a useful product. They also examined the possibility of combining devices for the gasification of WTP (step 1) with high-temperature solid oxide fuel cells (SOFCs) able to directly convert the WTP-gas into electricity.
The scientists used a techno-economic analysis to present a basic design process, overall energy balance and an economic study to assess the feasibility of WTP to electricity system on the scale of 10,000 tonnes of WTP per year.
The overall electric efficiency presented by the scientists is 57 per cent, which is similar to a natural gas combined cycle plant. The levelised cost of electricity (LCOE, a measure used for consistent comparison of electricity generation methods) is 20.3¢/kWh. This is comparable to current residential photovoltaic installations.
The capital costs for the system are high which is mainly due to high fuel cell investment costs; however, scientists expect this to decrease as the market for fuel cells grow.
The operating costs are relatively low due to high thermodynamic efficiency (ca. 70 per cent). The scientists expect learning effects could make the system more competitive in future – at an LCOE of about 11 ¢/kWh.
The research team believes that there is a great future for converting WTP into electricity as this is a continuously available resource compared to other sources of renewable energy. Plus the cellulose in the WTP comes from trees, making the electricity produced truly renewable, and can help in matching society’s demand for renewable energy in the future.
Who would have thought – waste toilet paper can be a valuable resource. Something we flush down the toilet may well be the answer to our energy needs in the future.
Source: Energy Technology
