Energy and Electricity - Introduction to Carbon Capture and Sequestration - page 27

spins a generator (essentially a spinning magnet within a coil of wire). As
the magnet spins within this coil, electricity flows through the coil. This
electricity can then be used immediately or stored in a battery. The amount
of electricity produced depends on the resistance of the bicycle, the speed
at which the cyclist can pedal, and the efficiency of the generator.
For our calculation, we will assume that each person generates a
125 W output with a 60% generator efficiency.
These estimates yield 270 kJ per person per 1 hour work day, or for
the entire world population, 1.86 × 10 15 J per day. Compared to the esti-
mated 1.76 × 10 17 J/day of global electricity consumption (17.8 trillion
kWh per year), this project will produce roughly 1% of the required world
electricity demand. (Or, if this experiment were arranged such that the
entire world population were to generate electrical power for only the
USA (which in 2009 consumed 3.7 Å × 10 16 J of electricity every day), it
would produce only 5% of the USA's electricity usage.)
We can also translate this energy to reduced carbon emissions. This
is a much more difficult calculation in practice as we also need to take
into account the amount of CO 2 that is emitted in manufacturing our bicy-
cles. Forgetting to factor in the contribution of manufacturing to carbon
emissions is a classic blunder made by students, policy makers and sci-
entists alike. Nevertheless, we forge ahead and ignore this contribution.
In the USA, it is known that the population emits about 0.67 kg of CO 2 for
each kWh of electricity generated. Using this information, we can easily
quantify the carbon emissions avoided due to the cycling program:

1kWh 0.67 kg CO

15 2

1.86 10 J per day

× ¥ ¥

3600000 J 1 kWh

8

= 3.46 × 10 kg CO per day

2

This means that the cycling program will save 346 Gg (346 million kg) of
CO 2 emissions per day, assuming USA efficiencies apply worldwide.
Compared to the 91.78 Tg (91.78 billion kg) of total carbon dioxide emit-
ted per day, this program reduces carbon emissions by less than 0.5%.
This is yet another reminder of the enormous scale of carbon emissions
that we have to address.
Now let's look at sources of funding for our cycling project. What
about paying for it by taxing oil? Worldwide oil consumption is about 96
million barrels of oil per day. We can calculate the necessary tax to sup-
port the program by spreading its cost of $25 billion per day over the total