December 24, 2011
Christmas Waste Paper Could Be Turned Into High Grade Biofuel
UK's wrapping paper and festive cards could provide energy to send a bus to the moon more than 20 times
If all the UK's discarded wrapping paper and Christmas cards were collected and fermented, they could make enough biofuel to run a double-decker bus to the moon and back more than 20 times, according to the researchers behind a new scientific study.
The study, by scientists at Imperial College London, demonstrates that industrial quantities of waste paper could be turned into high grade biofuel, to power motor vehicles, by fermenting the paper using microorganisms. The researchers hope that biofuels made from waste paper could ultimately provide one alternative to fossil fuels like diesel and petrol, in turn reducing the impact of fossil fuels on the environment.
According to some estimates 1.5 billion cards and 83 square kilometers of wrapping paper are thrown away by UK residents over the Christmas period. They currently go to landfill or are recycled in local schemes. This amount of paper could provide 5-12 million liters of biofuel, say the researchers, enough to run a bus for up to 18 million km.
"If one card is assumed to weigh 20g and one square meter of wrapping paper is 10g, then around 38,300 tons of extra paper waste will be generated at Christmas time," said study author Dr Richard Murphy from the Department of Life Sciences at Imperial College London. "Our research shows that it would be feasible to build waste paper-to-biofuel processing plants that give energy back as transport fuel."
Co-author and PhD student Lei Wang, also from Imperial's Department of Life Sciences, said: "The fermentation process could even cope with festive paper and card which has been 'contaminated' with the likes of glitter and sellotape. The cellulose molecules in sellotape would be broken down into glucose sugars and then fermented into ethanol fuel, just like the paper itself. Insoluble items like glitter are easy to filter out as part of the process."
Dr Murphy added: "People should not stop recycling their discarded paper and Christmas cards because at the moment there is no better solution. However, if this technology can be developed further, waste paper might ultimately provide a great, environmentally friendly alternative to fossil fuels. There's more work to do to assess the effectiveness and benefits of the technology, but we think it has significant potential."
In the study, published this month in the Royal Society of Chemistry journal Energy and Environmental Science, the researchers describe how they fermented different types of paper and cardboard in the laboratory to assess how chemically and economically feasible it is to turn them into ethanol fuel. They found that it is not only possible in laboratory experiments but should be economically viable on a large scale as well.
Across the year, around 60 per cent of the UK's waste paper is collected for recycling or other waste management schemes, which equates to around 8 million tons. The scientists say that using a well-tested fermentation method and a novel cocktail of efficient and cheap chemical enzymes, their system could be scaled up to the size of existing industrial processing plants and be used to convert 2000 tons of waste paper per day into biofuels.
There is already an urgent need for councils to prevent reusable materials like cardboard and paper being sent to landfill sites, saving money and avoiding unnecessary waste, a message echoed by the Mayor of London Boris Johnson in a speech about Recycle for London's Nice Save campaign this week. This new research shows that in addition to recycling, waste materials can be used to generate energy, and some of that can be as valuable vehicle fuel.
High grade ethanol, such as that made in this study, can be (and already is) blended with fossil-based petrol to make a fuel with lower greenhouse gas balance than conventional petrol for cars and vans, and can also be used to power large diesel vehicles like buses and trucks, if modifications are made to their engines. This approach is already used in Brazil, the USA and the EU, among other regions, where ethanol biofuels are being made from sugar cane, grain and other crops. Most of the UK's biofuel is currently imported from abroad.
The authors of this study are now analyzing the environmental performance of bioethanol made from waste paper using life cycle assessment (LCA) and comparing it with the conventional transport fuel petrol. LCA is an environmental management tool that evaluates the 'cradle-to-grave' effects of a product for its influence on a range of environmental impact categories, including its ability to contribute to climate change or soil acidification or to cause algal blooms in fresh water.
1. Journal reference: Wang L, Sharifzadeh M, Templer R and Murphy RJ. "Technology performance and economic feasibility of bioethanol production from various waste papers" is published in Energy and Environmental Science DOI: 10.1039/C2EE02935A
2. The maths:
(1) Bioethanol predicted from using Christmas waste is 5.2-12 million L, energy content of ethanol is 22 MJ/L
(2) Economy mileage for a diesel bus is 39 L/100km (Wikipedia info) Diesel energy content is 38.6 MJ/L Bus running needs 15 MJ/km
(3) Bus using bioethanol can run 1.47 km/L
(4) Distance of bus running is 7.6-18 million km
(5) Times travelling to moon (distance is 0.38 million km) is 20-47 times
3. Globally, the annual bioethanol production from waste paper and cardboard has been estimated by Shi et al. to be in the order of 80 billion liters and world annual consumption of paper products in 2010 (400 million tons) could potentially amount up to 129 billion liters if all used papers were completely converted to bioethanol. These estimates suggest waste paper derived bioethanol could deliver a considerable potential to displace a useful proportion of petroleum demand. Overall, this comprehensive techno-economic analysis shows that bioethanol production from waste papers can be economically feasible.
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