Energy: some figures regarding. human energy needs

Saturday, 6 April 2013

Energy: some figures regarding. human energy needs
It requires 1 kilo calorie to heat 1 litre of water. It corresponds to 4,1868 kilo joules. Regardless of whether the energy is produced in a nuclear power plant or come from a plate of chocolate, As joules is the physical unit of measurement for energy. And whether it is a human or a machine: when something is heated or moves, energy will be used. Or rather: transformed energy, for example. from electrical energy to heat energy.

10 grams of milk chocolate delivers ca. 230 kilojoules, and it is enough to heat a litre of water to 55 degrees Celsius. With a little more exactly-288- kilojoules you can warm a room for an hour with an 80 w incandescent bulb. Admittedly converts only a small portion of the electrical energy to light, because machines, which transforms one form of energy to another, constantly emitting heat loss and therefore do not work with a 100% efficiency. And the incandescent light bulb uses only 5% of the "consumed" 288 kilojoules to illuminate the room-the rest goes to heat the bulb up.

A young man of average size should use ca. 380 kilojoules per hour by exertion. But by hard physical exertion, body use significantly more energy than it can either take from its fat stores, or can retrieve from a meal: A serving of Spaghetti Bolognese provides well over 3,000 kilo joules, a large serving of sauerkraut with meat and pea and potato puree gives approximately 6,000 calories. And it is enough to cover more than half of the daily energy needs for people with sedentary work. Daily energy needs vary naturally with body size, age and sex, but is usually of about 11,000 kilo joules per day.

In Germany will be a large part of the huge energy needs converted by oil and coal. These raw materials are not renewable  and it causes problems with exhaust fumes pumping carbon dioxide into the atmosphere when they are converted into electric energy so that it is why scientists are looking for alternatives. And here comes the nuclear power into the picture: By splitting of atomic nuclei released a tremendous amount of energy (one gram of uranium-235 provides approximately 67.000.000 kilo joules), but in addition the well-known problems with radioactive waste and the risk of catastrophic accidents. Therefore, science is trying to focus and in the industrialized world utilize renewable energy sources, especially wind and solar power. In principle, the potential is enormous: up to kilo joules on a 9-hour sunny day a surface of only 1 km2. If one imagines that this energy source were utilized in the Sahara with only 1/10 converted to electricity, so would an area of only 9 x 9 meter be enough to cover one citizen's needs.

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