Resumo:
In several regions of the world and diferente countries there is a transition of the electricity matrix in
progress, driven mainly by environmental issues. However, there are geopolitical aspects involved,
suah as the interests of countries with a strong presence of coal in their energy matrix. In this context,
natural gas appears as a fuel for this energy transition. This perspective follows the increase in
investments in infrastructure of the natural gas market and the fact that, among fossil fuels, natural
gas is the fuel with the lowest greenhouse gas emissions. In addition, natural gas thermal power plants
are interesting for the complementarity and reliability of the system and energy security. In addition,
natural gas power plants are interestinh fot the complementarity and reliability of the system and
energy security. Therefore, the presente work aimed to carry out a comparative analysis of four termal
power Generation systems, being three coal-fired power plants (subcritical, supercritical and
ultrasupercritical) and a combined cycle plant with natural gas, from the exergetic point of view,
emissions of CO2 and annualized eletricity cost. Based on this comparison, a discussion was held
about under what conditions the use of natural gas can have its use expanded in the contexto of the
energy transition. It has been demonstrated that a combined cycle plant powered by natural gas with
57.95 % exergetic efficiency has an emission factor 60 % lower than that of a subcritical coal plant
and avoids about 3.5 Mt of annual CO2 emissions. An economic analysis was also carried out and it
was determined that the volatility of fuel prices has a strong influence on the cost of electricity.
According to market conditions, supply and demand, the combined cycle plants presented
competitive costs.
