(602d) Methanol and Formic Acid Syntheses Using Captured CO2 As Raw Material: Techno-Economic and Environmental Assessments

According to the Energy Roadmap 2050 [1], carbon capture and storage (CCS) will have to be present in 7% to 32% of the fossil fuel power generation contribution by 2050, depending on the scenario considered, to meet the 80-95% greenhouse gas (GHG) emissions reduction by 2050. The 2030 Climate and Energy Policy Framework [2], proposes the reduction of GHG to no less than 40% compared to 1990, by 2030. In 2013 the total CO₂ emissions in the power sector were of 3,400 MtCO₂, while the 2030 objective is to reduce the CO₂ emissions to 1,550 MtCO₂, in EU-28 [3]. CO₂management has a key role in these targets.

This work analyses the technological, environmental and economic barriers for producing methanol and formic acid from carbon dioxide, as well as the possible uses of methanol and formic acid in the European context. Methanol and formic acid are well known chemicals that can be used in the future transportation sector and as hydrogen carriers (i.e. mainly used as feedstock for fuel cells). They represent an alternative to intermittent sources of electricity production, as chemical energy storage options. In view of the current CCS efforts, carbon capture and utilization (CCU) can be an interesting proposition for the development of demonstration CO₂capture projects. The two studied CCU options are complementary between them, to other CCU alternatives and to CCS.

This study evaluates the potential of methanol and formic acid CCU plants on (i) the net reduction of CO₂ emissions and (ii) the cost of production, in comparison with the most used conventional synthesis process. We use a process system engineering (PSE) approach to calculate the key performance indicators (KPIs): technological, economic and environmental metrics. Technological metrics like mass and energy balances per tonne of product, CO₂ demand as raw material, CO₂ converted in the conversion processes and CO₂ used or retained in the process are considered. Economic metrics, such as the total fixed capital cost, costs of production and the gross margin, are calculated and analyzed. Environmental metrics, like CO₂ that is not produced if the CCU-based process is compared with its analogous conventional one, and the global amount of CO₂ avoided (that is not released into the atmosphere), as well as the CO₂ emission reduction obtained when using the CCU process instead of the conventional one, are investigated and discussed. The boundaries of the study are set on the CCU plant: this includes transportation to the plant (if needed), an electrolysis device to produce hydrogen, a CO₂ purification unit and the CCU plant itself. The models are implemented in the simulation software CHEMCAD, and the technologies are represented at their hypothetical market scale, comparable to their analogous conventional plants, i.e. 450 kt of methanol per year, and 11.5 kt of formic acid per year. Through a financial analysis, the metric net present value (NPV) for each one of the plants is used to evaluate the needed (i) price of CO₂ as raw material, (ii) H₂ production cost, (iii) price of O₂as byproduct, or (iv) price of methanol and formic acid as products, in order to make the CCU-based process financially sustainable. In our market analysis (horizon 2030), we evaluate the possible penetration ways of methanol and formic acid, thus accepting a growing demand of both products. This future demand of methanol and formic acid, consider them utilized as in their current applications, as hydrogen carriers, as fuels in transport sector, and as fuel in residential applications. The defined penetration pathways are complementary.

According to our research, both processes represent a net saving of CO₂, when compared to their corresponding conventional processes which use fossil fuels as raw materials. However, boundary conditions (i.e. the source of CO₂, layout of the process, transportation distance, availability of renewable electricity) are important in defining a complete process that offers net CO₂ savings. The success and effectiveness of CCU will also depend on other technologies: the availability of (i) renewable hydrogen and (ii) access to low cost electricity. The results of this work put into manifest the trade-off between utilities, raw materials and products prices, as well as the threshold at which the CCU plant does not lead to CO₂ emissions reduction, but an increase of them. CO₂compression and water electrolysis are the objects of analysis.

Overall, the competitiveness of CO₂ utilization for the two options analysed in this work, will depend on how effective future implementation actions will be in dealing with renewable electricity, transportation sector fuels, hydrogen synthesis and use. According to the market analysis, the demand of captured CO₂ could be of 80 MtCO₂/yr.

References:

[1] M. Decker, L. Vasakova, Energy Roadmap 2050. Impact assessment and scenario analysis, Tech. rep., European Commission (EC), Brussels (December 2011).

[2] General Secretariat of the Council, Conclusions on 2030 climate and energy policy framework, Note, European Commission (EC), Brussels, available at: http://ec.europa.eu/clima/policies/2030/documentation_en.htm(last accessed December 2014) (October 2014).

[3] Eurostat, Early estimates of CO₂ emissions from energy use, News release, available at: http://europa.eu/rapid/press-release_STAT-14-74_en.htm  (last accessed December 2014) (2014).