Sunday, August 12, 2007

All the news that's fit to burn

Newspaper Innovation claims that in London every weekday, 400,000 copies of the London Lite and 500,000 copies of The London Paper hit the streets, almost literally as they are discarded on the floor. Have you ever wondered what that flow of newspapers would be worth as a source of energy?

My friend weighed an typical London paper and came up with 100 grammes. So we have just short of 65 tonnes of newspapers per day, every day, on average (i.e. averaging the weekdays over the weekend too).

What is a kilogramme of newspaper worth, in energy terms? Aysen Ucuncu at the Department of Civil and Environmental Engineering at Duke University comes up with a figure of 7540 BTU/lb, or 4.9 kWh/kg. So we can calculate 13 MW of potential thermal power flows onto London's streets, embodied in the carbon bonds of those free newspapers.

What could that potential be worth? Imagine you could collect all the newspapers up, without expending a single Joule of energy in the process, and burn them in a biomass boiler. Let's say you attached the boiler to a generator to make electricity at maybe 27% efficiency and sold it for £32/MWh, a typical long-term contract price for electricity from a waste-to-energy plant in London. You'd get £1m per year, or roughly 0.4 pence/newspaper.

Are the newspapers a significant source of energy? No. Burning them would supply only 0.04% of the average UK primary energy demand per person (13 MW of power over a readership of 7 million Londoners is 0.04 kWh/day/person, while average UK demand is 120 kWh/day/person).

Funnily enough, if you were to ever read one of these papers, it wouldn't be long before you read that you should unplug your mobile phone charger, for the sake of climate and energy security. But leaving a phone charger plugged in these days typically draws less than 1 W of electricity, or less than 0.02 kWh/day. You could generate electricity at more than five times that rate by burning your daily paper in the scheme above. Whether you thought it was worth reading first is up to you. All I can say is unplugging your mobile phone charger isn't going to save the planet.

8 comments:

Damon said...

Hi,

According to Hans Blix http://www.world-nuclear.org/sym/2001/blix.htm 1kg of wood is worth about 1kWh of electricity, so assuming that a newspaper is of similar calorific content to wood, his numbers line up close enough with yours.

Though we've worked hard to cut the junk mail we receive (it used to be inches per day) we still have local free newspapers, cardboard packaging, etc, so it would be nice in principle to be able to combust these in winter to take the edge off our heat demand.

But at ~50kWh/day in the coldest month, even just taking the heat as heat, that implies 10kg of newsprint and other paper waste, even with 100% efficiency. Our poor postie (et al) has to be glad not to be delivering that each winter's day!

And my typical commute into and out of London by public transport is equivalent to ~7kWh/day electricity on days when I travel, so getting on for another 100 free newspapers!

Rgds

Damon

Damon said...

Let's hear about your contribution to the BBC survey: it looked reasonably constructed to me. Presumably you felt so or would not have participated...

Rgds

Damon

Anonymous said...

Tim, if the issue is how to get net energy from newsprint, then the obvious answer is: don't make any. Pulp and paper production is notoriously energy-intensive. See

http://oee.nrcan.gc.ca/publications/infosource/pub/cipec/pulp-paper-industry/Section-03.cfm?attr=20

Now that e-readers like Amazon's Kindle are making headway, and newspapers are mostly available online, why continue to deforest vast areas, pollute rivers, and use enormous amounts of energy, just to put words on cellulose? If we go the Kindle one better and develop and market cheap, lightweight fold-out electronic reading-screens with Wii connectivity, we can do away with newsprint altogether without having to lug laptop computers about.

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Dan said...

I guess if the issue is how to get net energy from newsprint, then the obvious answer is: don't make any. Pulp and paper production is notoriously energy-intensive.

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Anonymous said...

nice numbers, thanks for the post!

tin said...

nice forum i like

Akram said...

Good post. These so-called "news"papers are only free of content but not free as in no environmental impact.