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Avaliação da Tecnologia de Captura Direta de CO2 como opção de mitigação climática
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As alterações climáticas são, atualmente, a maior ameaça ambiental. Estas mudanças estão
diretamente relacionadas com a intensificação da concentração de gases efeito de estufa na atmosfera
e com o consequente aumento da temperatura média global do Planeta. Em consonância com os
objetivos do Acordo de Paris de limitar o aumento da temperatura média bem abaixo do 2°C compa-
rativamente à era pré-industrial, foi aprovada a Lei Europeia do Clima que torna vinculativo atingir a
neutralidade carbónica em 2050 na União Europeia. No entanto, reconhecendo o resultado positivo
das políticas climáticas na redução das emissões, o relatório do IPCC (2021) revela que as políticas
atuais estão em linha com o aumento da temperatura média global do Planeta de 2,6° C a 2,7° C no
final do século.
Consciente dos impactes nos sistemas naturais e para a humanidade e da urgência em reesta-
belecer a concentração de CO2 a níveis compatíveis com o aumento da temperatura dentro dos limites
de segurança, reconhece-se a necessidade da captura de CO2 defendida por autores como Kramer
(2020), Realmonte et al., (2019) e Easac (2018), apoiando o desenvolvimento de tecnologias designa-
das de emissões negativas, como a Captura Directa da Atmosfera (DAC, na sigla em inglês). A tecno-
logia DAC tem a capacidade de capturar CO2 diretamente da atmosfera, por entrada forçada de ar,
permitindo o contacto do ar rico em CO2 com o absorvente, libertando de novo o ar para a atmosfera,
livre de CO2.
A presente dissertação visa compreender o papel da tecnologia DAC, enquanto opção de miti-
gação climática, e avaliar a sua oportunidade em Portugal. Numa primeira fase, pretende-se conhecer
os custos e dados técnicos desta tecnologia, atuais e para o futuro, e entender os seus impactes em
termos de consumo de energia, nomeadamente de gás natural e eletricidade. Como alternativa tecno-
lógica para uma análise comparativa, considera-se as tecnologias de captura e utilização de CO2
(CCUS).
Numa segunda fase, e de modo a ter uma visão comparativa e integrada das tecnologias DAC
e do seu potencial para a descarbonização de Portugal, foram analisados os custos e o balanço de
emissões e respetivas opções tecnológicas associados à cadeia do CO2, desde a sua captura, trans-
porte e posterior armazenamento ou utilização. Por fim, é avaliado o potencial custo-eficaz das DAC,
utilizando resultados obtidos com a ferramenta de modelação integrada TIMES_PT, para a descarbo-
nização do sistema energético nacional até 2050.
A implementação da tecnologia DAC para a meta de redução de 90% de emissões do sistema
energético nacional em 2050 face a 2005, permite a transição mais lenta do sistema energético portu-
guês, refletindo-se, particularmente, no consumo de gás natural no setor da indústria e dos edifícios.
Quando a DAC é considerada como complementar às políticas e estratégias já implementadas, permite
atingir reduções de emissões mais ambiciosas, de 95% e 99%, demonstrando-se custo eficaz a partir
de 2040. A utilização do CO2, resultado da captura direta, revela-se custo eficaz para a produção de
querosene, gasóleo e gasolina, resultado que diverge da Estratégia Nacional do Hidrogénio (EN-H2)
aprovada em 2020.
Climate change is currently the biggest environmental threat. These changes are directly related to a higher concentration of greenhouse gases in the atmosphere and consequently to a higher global average temperature of the Planet. In line with the Paris Agreement goals to limit the increase of the global average temperature well-below 2ºC comparatively to the pre-industrial era, the European Cli- mate Law was approved, making carbon neutrality in 2050 in the European Union a binding target. However, even recognizing the positive result of climate policy in reducing emissions, the IPCC (2021) reveals that current policies are in line with an increase of the global average temperature of the Planet in 2,6ºC to 2,7ºC at the end of the century. Aware of the impact in natural systems, as well as in humanity, and regarding the urgence to re- establish CO2 concentration in levels compatible with an increase of temperature within safe limits, CO2 capture is considered necessary by authors such as Kramer (2020), Realmonte et al. (2019) and Easac (2018), who support the development of the so-called negative emission technologies, like the Direct Air Capture (DAC). This technology is capable of capture CO2 directly from the atmosphere, through forced entry of air, allowing the contact of rich CO2 air with the absorbent, thus releasing the air back into the atmosphere free of CO2. This dissertation aims to understand the role of DAC technology, as an option for climate mitiga- tion, and to evaluate its opportunity in Portugal. On a first stage, the costs and technical data of this technology will be assessed, both currently and in a future perspective, and to understand its impact in energy consumption, namely natural gas, and electricity. As a technological alternative for a compara- tive analysis, we will consider CO2 Capture, Utilization and Storage technologies (CCUS). On a second stage, in order to get a comparative and integrated view of DAC and its potential for decarbonisation in Portugal, the costs and emissions balance were analysed, as well as the tech- nological options related to the CO2 chain, from its capture, transport and storage or utilization. At last, the evaluation of the cost-effectiveness of DAC is performed, based on results from the integrated modelling tool TIMES_PT, for the decarbonisation of the national energetic system until 2050. Implementing DAC technologies in order to reach a reducing emissions target of 90% of the Portuguese energy system by 2050 when compared to 2005, allows a slower transition reflected par- ticularly in the final energy consumption of natural gas in the industry and building sectors. When DAC is considered as complementary to the policies and strategies in place, it allows to reach more ambitious emission reductions, as 95% and 99%, proving cost-effective from 2040 onwards. The utilization of CO2 as a result from direct capture appears cost-effective for the production of kerosene, diesel and gaso- line, a result that differs from the National Hydrogen Strategy (EN-H2) approved in 2020.
Climate change is currently the biggest environmental threat. These changes are directly related to a higher concentration of greenhouse gases in the atmosphere and consequently to a higher global average temperature of the Planet. In line with the Paris Agreement goals to limit the increase of the global average temperature well-below 2ºC comparatively to the pre-industrial era, the European Cli- mate Law was approved, making carbon neutrality in 2050 in the European Union a binding target. However, even recognizing the positive result of climate policy in reducing emissions, the IPCC (2021) reveals that current policies are in line with an increase of the global average temperature of the Planet in 2,6ºC to 2,7ºC at the end of the century. Aware of the impact in natural systems, as well as in humanity, and regarding the urgence to re- establish CO2 concentration in levels compatible with an increase of temperature within safe limits, CO2 capture is considered necessary by authors such as Kramer (2020), Realmonte et al. (2019) and Easac (2018), who support the development of the so-called negative emission technologies, like the Direct Air Capture (DAC). This technology is capable of capture CO2 directly from the atmosphere, through forced entry of air, allowing the contact of rich CO2 air with the absorbent, thus releasing the air back into the atmosphere free of CO2. This dissertation aims to understand the role of DAC technology, as an option for climate mitiga- tion, and to evaluate its opportunity in Portugal. On a first stage, the costs and technical data of this technology will be assessed, both currently and in a future perspective, and to understand its impact in energy consumption, namely natural gas, and electricity. As a technological alternative for a compara- tive analysis, we will consider CO2 Capture, Utilization and Storage technologies (CCUS). On a second stage, in order to get a comparative and integrated view of DAC and its potential for decarbonisation in Portugal, the costs and emissions balance were analysed, as well as the tech- nological options related to the CO2 chain, from its capture, transport and storage or utilization. At last, the evaluation of the cost-effectiveness of DAC is performed, based on results from the integrated modelling tool TIMES_PT, for the decarbonisation of the national energetic system until 2050. Implementing DAC technologies in order to reach a reducing emissions target of 90% of the Portuguese energy system by 2050 when compared to 2005, allows a slower transition reflected par- ticularly in the final energy consumption of natural gas in the industry and building sectors. When DAC is considered as complementary to the policies and strategies in place, it allows to reach more ambitious emission reductions, as 95% and 99%, proving cost-effective from 2040 onwards. The utilization of CO2 as a result from direct capture appears cost-effective for the production of kerosene, diesel and gaso- line, a result that differs from the National Hydrogen Strategy (EN-H2) approved in 2020.
Descrição
Palavras-chave
Captura Direta de CO2 DAC LT DAC HT armazenamento offshore armazenamento onshore utilização de CO2