We, as humans, produce a lot of waste. Also, we need a tremendous amount of energy to keep our civilization running. So why not combine these two problems? Scientists the University of Amsterdam cooperated with colleagues from the Copernicus Institute of Sustainable Development of Utrecht University have now finished analysing what would it take to convert used toilet paper into electricity.
You may not think about this, but humans produce astonishing amounts of waste toilet paper. For example, on average people in Western Europe produce 10–14 kg waste toilet paper per person per year. Flushed paper ends up being gathered in municipal sewage filters and then usually gets composted. Really, as paper is, generally speaking, biodegradable, it is not too big of an issue. However, it is a significant amount of material, which could be put to a better use if technological solutions would be found. Scientists proposed such solution, which involves a two-step process, and calculated a cost per kWh comparable to that of residential photovoltaic installations. So what’s that two-step process?
At first waste toilet paper would go through gasification process and then it would be burned in high-temperature solid oxide fuel cells. Scientists thought that this may be the best bet in trying to convert used toilet paper into electricity, but of course it also has to be economically viable. Dry waste toilet paper is a rich source of carbon, containing 70–80 % of cellulose by weight. This means that gasification process and the subsequent burning would not be too technologically challenging – it is possible. Scientists calculated the cost and benefit from converting 10.000 ton WTP per year.
Taking into account the 57 % efficiency, it is possible to reach overall price of 20.3¢/kWh. This is actually not too high, since this is comparable to residential photovoltaic installations. Maintenance costs should be low as well, but capital investment at the very beginning is bound to be rather large. However, the model is scalable and could cost less potentially if a larger number of such fuel cells is installed. Furthermore, recycling waste toilet paper would be good for the environment in the long run and it is a material with a negative cost – cities would pay facilities to take them.
Scientists want to put their ideas into use. However, the first country to employ such system is likely not to be Netherlands – scientists are pointing their eyes towards China. But we will have to wait and see if this develops into something productive.
Source: University of Amsterdam