Powering the world

Energy – why is it so important, where do we get it and how much do we use? Gieljan de Vries from the Dutch FOM-Institute for Plasma Physics Rijnhuizen^w1 investigates.

Forget the dollar, the euro, and the yen. If you want to get anything done in the world, you need to spend energy. Moving a car, powering a computer or creating something in a factory – all these things require energy. So what is energy, and how does it shape our world?

Physicists define energy as the ability to do work. That’s a pretty abstract definition, because the concept of energy applies to so many different situations and materials. Pick any task, and you can calculate the total amount of energy in joules (J) that is needed to complete it, or the power (energy per second) that a process consumes in watts (W; equal to J/s). It turns out that every aspect of our lives has an energy price we have to pay.

Humans use energy all the time. Just sitting there, your body needs around 100 W of power. Energy powers muscles such as your heart and enables biochemical reactions in your organs. Of course, people do more than just sit around. Walking up the stairs or lifting boxes, we can produce around 100 W of useful power for hours on end. However, to do so, our muscles will consume 300-400 W – three to four times the energy they produce. A European household of three to four people continuously consumes an average of about 400 W by running heaters, powering electrical devices and so on. It would take twelve people on treadmills (four per shift in three shifts of eight hours) to provide that much power.

Coal, oil and gas are used in roughly equal quantities to generate the world’s energy needs, but oil has perhaps the most visible use of the three: all kinds of transportation are utterly reliant on the fuels produced from it. Burning a standard barrel of oil, holding 159 litres, will release around 6100 MJ (million joule) of energy. Not only is that a lot of energy, it’s also unbelievably cheap. Even though the price for a barrel of oil has fluctuated between €30 and €150 in the past year, a human would have to perform hard labour for 22 000 hours to release the amount of energy contained in one barrel. That’s 11 years spent on a treadmill every workday from 9 am to 5 pm. Good luck finding anyone who would work that long and hard for that kind of money!

Back to our average energy use: we need more than the 100 W each person minimally consumes or the 400 W powering our house to maintain our way of life – consider the energy used to produce and transport household appliances in the first place. It turns out that a nation’s households are responsible for about a quarter of its energy use, with transportation and industry each responsible for another third. Businesses, infrastructure and agriculture fill out the list of energy consumers.

Let’s put things into perspective: in 2006, the European Union used 49.2 TJ (terajoule) of energy. That’s 49 million million joule, a truly staggering amount. Even spread out over 500 million Europeans, our yearly energy consumption is huge: 95 800 MJ for each of us (about 16 barrels of oil). For the whole of Europe, we would have had to burn the equivalent of 1176 million tons of crude oil to release that much energy, enough to fill a lake 20 metres deep and 20 by 30 kilometres wide. And that’s just to satisfy the annual European demand for energy. That year, the USA used the equivalent of 2340 million tons of oil and China burned up 1717 million tons. China’s energy use has increased spectacularly since their fast economic growth began. But counted per citizen, China is still not a wasteful energy user: each Chinese citizen uses the equivalent of 1.3 tons of oil per year. A US citizen, however, uses 7.4 tons of oil, and a European averages at 3.7 tons per year.

Every year, a fleet of 3500 oil tankers, some of them 400 meters long, ships 2000 million tons of oil across the globe. That’s not all of the oil we use, because pipelines transport another part of the load. In 2006, the world used 3481 million tons of oil, providing 43% of the worldwide energy demand.

The world demands more energy. In the short term, this means more use of fossil fuels. Polluting coal plants, previously unpopular, are now built to the tune of one every week in China. The demand for oil alone is projected to rise by 47% by 2030, and companies search the harshest of environments, such as the deep sea or the arctic, for natural gas to fuel power plants and factories. According to the International Energy Agency (IEA), these investments will keep the share of fossil fuels around 81% of the energy mix. In absolute terms, the total energy requirements – and, because of that, the demand for fossil fuels – is expected to rise by almost a half in 2030.

One day, the fossil reserves will run out. Coal mines can last roughly another 200 years at the current rate of use. Oil production, some fear, has already peaked: the IEA is afraid that existing oil fields are producing less and less each year, and too few new fields are being discovered to stop the slow decrease in production. We’re going to need sustainable forms of energy if we want to prevent conflict over the diminishing reserves. Besides, the way fossil fuels increase climate change through the greenhouse effect is very worrying, and calls for sustainable sources of energy.