Page 354 - Decision Making Applications in Modern Power Systems

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equivalent to 1 t of carbon dioxide that was allowed to emit into the atmo-
sphere. They may be generated through the mechanisms established in the
Kyoto Protocol. As the mechanism exists, different types of credits are pro-
vided [39,40].
In other words, these credits are used to make it easy to calculate the
amount of gases that are released into the air and offset their emissions. It is
part of an international plan, probably the largest, that has been created in
human history, to reduce global warming and effects. It is even the total
amount of emissions that can be released by a company or business. If there
is an excess amount of gases that are emitted, there is a monetary value
assigned to that excess and can be traded, especially for projects that offset
pollution, that is, to renew dioxide that has been emitted into the atmosphere,
such as reforestation projects (usually in poor or developing countries).
It is well known that some companies think if they can bribe, they would
be illegally allowed to pollute. In addition, there are credits that are bought
and sold in international markets. So, this may be the object of speculation
and does not have to be used to care for the environment.
By convention, 1 t of carbon dioxide (CO 2 ) represents 1 carbon credit.
This credit can be negotiated in international market. Reducing the emission
of other gases, also generators of greenhouse effect, it can also be converted
to carbon credits, using the concept of carbon equivalent (carbon dioxide
equivalent) [41].
A ton of CO 2 equivalent corresponds to a carbon credit. The CO 2 equiva-
lent is the result of multiplying the tons of greenhouse effect emitted by its
global warming potential. The global warming potential of CO 2 was set to 1.
The global warming potential of methane is 21 times greater than CO 2
potential, so the CO 2 equivalent of methane is equal to 21. Therefore a
reduced ton of methane corresponds to 21 carbon credits [18,42,43].
Global warming potential of greenhouse gases is as follows [44, 45]:
CO 2 —carbon dioxide 5 1
CH 4 —methane 5 21
N 2 O—nitrous oxide 5 310
HFCs—hydrofluorocarbons 5 140 11,700
PFCs—perfluorocarbons 5 6500 9200
SF 6 —sulfur hexafluoride 5 23,900

Since 2008 the price of carbon credits traded to sell to the developed
countries in America (CO 2 Certificate of Emission Reduction) fell 98%,
from 23 euros per ton to only 35 cents of euro per ton. The value of
securities is traded in the domestic market in Europe—European Union
Allowance. In turn, it fell from 30 to 4 euros [40]. Basically, considering the
concept of supply and demand, there is currently an excess of credit carbon,
which is a problem. In fact, the latest figures estimate that the market is satu-
rated in about 1700 million tons of carbon credits.