A Quadrillion Joules in a Biscuit A Quadrillion Joules in a Biscuit
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Marian Eile – drawing from the archives (no. 232/1949)
Science

A Quadrillion Joules in a Biscuit

What Is Energy?
Łukasz Lamża
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time 11 minutes

After putting the data into Einstein’s model, it turns out that one chocolate biscuit should satisfy the daily energy requirements of 200 million people. So what’s the problem?

Physicists are excellent at juggling energy: they add it, take it away, multiply and divide it; convert it from one form to another. However, if you ask them a simple question, such as how much energy does one biscuit really have, the trouble begins.

A cosmic relay

The packaging says that one biscuit from the pack weighs 13.5 grams and contains 67 kcal, i.e. 280 kJ (joules and calories are simply two different units for measuring energy, in the same way kilometres and miles are two different units for measuring distance). After eating the biscuit, that amount of energy is added to my body’s ‘energy pool’, which allows me, for example, to click away on my keyboard for half an hour in a seated position, or spend five minutes sprinting. And here we have a textbook example of the conversion of energy: from chemical energy, in the fats and sugars of biscuits, to kinetic energy, i.e. movement. If we were to examine the cells of my muscles under a microscope when they receive the order “Contract!”, we would observe that the adjacent molecules of actin and myosin move relative to each other in response to this order. The change in shape of these molecules is precisely that fundamental moment when chemical energy is changed into movement. Each time the actin molecules bend, this

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Illustration by Michał Loba
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The Trouble with Nuclear Energy
Andrzej Krajewski

No other power-generating device raises as much concern as the nuclear reactor. Because of this, until recently the future of the entire energy sector has been determined by its past.

On the eve of the pandemic, the European energy sector found itself at a crossroads, somewhere between Great Britain, Germany and Poland. Five years ago, across the English Channel, the then Prime Minister David Cameron announced an ambitious program to build 12 new nuclear power plants with a total capacity of 16 GW. While developing renewable energy resources, they would allow the United Kingdom to reduce carbon dioxide emissions from the energy sector to almost zero. Soon after, Cameron came up with the idea of a referendum on leaving the EU – and Brexit reset all long-term British plans. However, the British are already producing electricity in a very sustainable way. Almost 38% comes from renewable sources, about 20% from nuclear power plants, while the remainder is provided by gas-powered plants, the only ones that emit CO2.

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