Energy and man. A series of random comparisons
In physics, the semi-scientific “dimension method” is sometimes used to solve problems; when knowing the dimension of the desired quantity, we can guess what to divide, add, multiply to get the correct answer. I decided to take the dimension of “energy” and compare “apples with bananas,” namely, man as an energy system with other systems.
What is measured, energy?
Disclaimer: All calculations may not be accurate and the main goal is to show the order of numbers.
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An average person consumes about 2000 calories per day, which gives about 2 kWh or about 100 watts, average power. You can imagine that a person eats like one big 100-watt bulb.
The power consumption of a person is relatively small compared to the devices that surround us. We can say that man made a technical revolution. A person takes “into himself” less energy than he uses “for himself” even at home (the average calculation is more than 100 kWh per month).
It is common to estimate that the brain eats from 200 to 1000 Kcal (stressful situations), that is, from 20% -40% of energy, which gives an estimate of the average power of 30 watts.
The brain is an extremely effective system. Yes, modern laptops produce operations much better than us and the average power is about 30 watts, and phones in general are 0.5-1 watts. But modern video cards consume an average of 250 W and still cannot compare with the brain in terms of speed and accuracy of processing visual information. So, the person is a very good processor, but only for specific tasks.
They say a person can not eat 3-7 days. It is clear that without eating, a person will begin to consume less energy for internal and external needs. It can be assumed that after eating a double daily rate, a person will be active for 2 days (if there is water), which gives a rough estimate of 10 kWh.
If we calculate the energy intensity of a person, then we can get extremely different figures, the weight of people who can live the Nth number of days and produce some useful work varies greatly from 50 kg to 150 kg. Most likely, the average energy consumption is 0.1 kWh / kg, which is not so good and not so bad. We are located between gasoline (10 kWh / kg) and Liion (0.1 kWh / kg), closer to the batteries.
Today's solar panel gives about 300 watts in peak, in temperate latitudes, the average capacity factor of up to 20% (the sun shines only during the day and weakly). We know that a person is short-lived, but still a battery, so an average of 2 panels is enough for a person to eat only the sun.
If we drop the conventions and make small breakthroughs in technology (the use of expensive elements makes it possible to achieve up to 40% efficiency in panels), it will be enough for a person to wear “sunny clothes” in order to get all the necessary energy.
I will quote an article about clothes : at rest, the human body produces 80 watts of heat, while losing 10 watts due to breathing, 30 watts of heat radiation, 20 watts of heat conduction and convection, and 20 watts of moisture evaporation.
It turns out the person is extremely "weak" heater. Home heaters consume 1 kW and they only partially cover heating needs. Heated water and space heating in principle is the largest household power consumption. I will give my annual alignment:
- Movement (transport, fuel): 8 000 kWh per year.
- Electricity: 2 500 kWh per year.
- Water heating and heating: 30 000 kWh per year.
It turns out that the average daily water heating and heating takes up to 100 kWh per day, which is 50 times more than a person consumes in principle.
Man as an active living being can move in space. Suppose a person can move 30 km per day on foot and 120 km per day by bike. This is not the maximum value, of course, athletes run up to 100 km and drive up to 1000 km per day.
Let's try to compare a person as an effective system of human movement.
- A car with an internal combustion engine spends an average of 5 liters per 100 km, 1 liter = 10 kWh, which gives 500 Wh per km
- Electric car - 150-200 Wh / h per km
- Pedestrian - 2 kW * h divided by 10-50 km, 50-200 WH / km per km
- Slow / small electric car - 50-100 Wh / h per km
- Electric bike - 10 W * h / km (average speed of 10-15 km / h )
- Cyclist - 2 kW * h divided by 100-1000 km, 2-20 Wh * h per km
You know more interesting matches - write in the comments.
Thanks for attention.
What is measured, energy?
Disclaimer: All calculations may not be accurate and the main goal is to show the order of numbers.
')
Man is a consumer of energy. 2 kWh, 100 W
An average person consumes about 2000 calories per day, which gives about 2 kWh or about 100 watts, average power. You can imagine that a person eats like one big 100-watt bulb.
The power consumption of a person is relatively small compared to the devices that surround us. We can say that man made a technical revolution. A person takes “into himself” less energy than he uses “for himself” even at home (the average calculation is more than 100 kWh per month).
Man is a computer. 30 W
It is common to estimate that the brain eats from 200 to 1000 Kcal (stressful situations), that is, from 20% -40% of energy, which gives an estimate of the average power of 30 watts.
The brain is an extremely effective system. Yes, modern laptops produce operations much better than us and the average power is about 30 watts, and phones in general are 0.5-1 watts. But modern video cards consume an average of 250 W and still cannot compare with the brain in terms of speed and accuracy of processing visual information. So, the person is a very good processor, but only for specific tasks.
The man is the battery. 10 kWh
They say a person can not eat 3-7 days. It is clear that without eating, a person will begin to consume less energy for internal and external needs. It can be assumed that after eating a double daily rate, a person will be active for 2 days (if there is water), which gives a rough estimate of 10 kWh.
If we calculate the energy intensity of a person, then we can get extremely different figures, the weight of people who can live the Nth number of days and produce some useful work varies greatly from 50 kg to 150 kg. Most likely, the average energy consumption is 0.1 kWh / kg, which is not so good and not so bad. We are located between gasoline (10 kWh / kg) and Liion (0.1 kWh / kg), closer to the batteries.
Man is a consumer of solar energy. 1-2 solar panels
Today's solar panel gives about 300 watts in peak, in temperate latitudes, the average capacity factor of up to 20% (the sun shines only during the day and weakly). We know that a person is short-lived, but still a battery, so an average of 2 panels is enough for a person to eat only the sun.
If we drop the conventions and make small breakthroughs in technology (the use of expensive elements makes it possible to achieve up to 40% efficiency in panels), it will be enough for a person to wear “sunny clothes” in order to get all the necessary energy.
Heater Man
I will quote an article about clothes : at rest, the human body produces 80 watts of heat, while losing 10 watts due to breathing, 30 watts of heat radiation, 20 watts of heat conduction and convection, and 20 watts of moisture evaporation.
It turns out the person is extremely "weak" heater. Home heaters consume 1 kW and they only partially cover heating needs. Heated water and space heating in principle is the largest household power consumption. I will give my annual alignment:
- Movement (transport, fuel): 8 000 kWh per year.
- Electricity: 2 500 kWh per year.
- Water heating and heating: 30 000 kWh per year.
It turns out that the average daily water heating and heating takes up to 100 kWh per day, which is 50 times more than a person consumes in principle.
Man - vehicle (pedestrian, bicycle)
Man as an active living being can move in space. Suppose a person can move 30 km per day on foot and 120 km per day by bike. This is not the maximum value, of course, athletes run up to 100 km and drive up to 1000 km per day.
Let's try to compare a person as an effective system of human movement.
- A car with an internal combustion engine spends an average of 5 liters per 100 km, 1 liter = 10 kWh, which gives 500 Wh per km
- Electric car - 150-200 Wh / h per km
- Pedestrian - 2 kW * h divided by 10-50 km, 50-200 WH / km per km
- Slow / small electric car - 50-100 Wh / h per km
- Electric bike - 10 W * h / km (average speed of 10-15 km / h )
- Cyclist - 2 kW * h divided by 100-1000 km, 2-20 Wh * h per km
You know more interesting matches - write in the comments.
Thanks for attention.
Source: https://habr.com/ru/post/373741/
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