Reducing greenhouse gas emissions – Optimizing current value chains and implementing circular technologies
By Aline Kalousdian, Process Engineer for Life Cycle Assessment, Carbon Minds, and Raoul Meys, Co-Founder and CTO, Carbon Minds
To align with the long-term goal of the Paris Agreement to reach net-zero around mid-century, over 150 countries have recognized the urgent need to curb global greenhouse gas emissions (GHG). One large contributor is the chemical and petrochemical industry, representing approximately 4% of global annual GHG emissions. These emissions mainly originate from two factors. The first factor is using fossil fuels to provide process energy. To reduce these emissions, renewable energy, such as wind, solar, or bioenergy, can produce electricity, heat, and steam. The second factor increasing emissions is using fossil feedstock, such as coal, oil, or natural gas, as the carbon backbone of chemicals and petrochemicals. Here, emissions occur due to process inherent characteristics, like the formation of CO2 during ethylene oxide production and at the end-of-life when the carbon turns to CO2, for instance, due to waste incineration. Reducing emissions associated with fossil feedstock use is, thus, more complex since it needs to account for multiple production technologies and downstream value chains.
Simplifying, however, two main levers can reduce greenhouse gas emissions due to fossil feedstock use. The first lever is optimizing the existing chemical value chain to use less emission-intensive fossil feedstocks and processes which can be applied immediately. The second lever is more long-term oriented to achieve net-zero chemical and petrochemical value chains. For this purpose, the chemical and petrochemical industry must either combine fossil-feedstock use with Carbon Capture and Storage (CCS) or stop using fossil feedstock completely, i.e., move to waste, biomass, or CO2 plus hydrogen as a feedstock. To highlight the two levers to reduce emissions from feedstock use, we will first highlight the potential for immediate action by outlining the greenhouse gas emission of crude oil production. Second, we will describe a vision for realizing net-zero chemical and petrochemical value chains, highlighting the need for a combined approach of all technological options to achieve a long-term beneficial future.
The existing fossil value chain of chemicals and petrochemicals uses coal, natural gas, and crude oil as feedstock. Since crude oil is the primary source of fossil feedstock in the Arabian Gulf, Figure 1 illustrates the greenhouse gas emissions per barrel related to crude oil production across 49 regions globally, normalized to the highest emitting production country. Overall, a reduction of almost 97% is possible from the highest to the lowest crude oil production region. For countries present in the Arabian Gulf, 86% to 93% reductions are possible, depending on the country.
Figure 1 – Global greenhouse gas emissions per barrel related to crude oil production across 49 regions, normalized to the highest emitting production country.
This difference in greenhouse gas emission is driven by three main factors: (1) gas flaring rates, (2) venting, and (3) fugitive emissions during production and distribution. While gas flaring rates are considered independently, venting and fugitive emissions during production and distribution are jointly discussed due to their contribution to the unburned and unintended gas release into the atmosphere. The gas flaring rates per barrel of crude oil in the Arabian Gulf countries are estimated to be five to 44 lower than the highest reported gas flaring rates. A similar trend can be observed for venting and fugitive emissions during production and distribution. The unburned and unintentional gas release per barrel of crude oil in the Arabian Gulf ranges between 4% to 9 % of the highest observed gas release value among analyzed countries. This difference is due to low to medium gas content in the wells of the Arabian Gulf countries, resulting in an overall lower gas flaring fates, venting, and fugitive emissions across these countries. Overall, the combination of relatively low gas flaring rates, venting, and fugitive emissions leads to lower greenhouse gas emissions per barrel of crude oil in the countries in the Arabian Gulf.
While the different crude oil greenhouse gas emissions highlight the potential to optimize the current value chain, maintaining fossil feedstock will not achieve net-zero greenhouse gas emissions. For this purpose, combining CCS with circular technologies, such as mechanical and chemical recycling, Carbon Capture and Utilization (CCU), and biomass utilization, is required to achieve net-zero in the long term (see Figure 2). These circular technologies are based on renewable carbon sources such as plastic waste, CO2, and biomass. Using these renewable carbon sources allows chemical production while decreasing the dependence on fossil feedstocks.
Renewable carbon sources from plastic wastes are obtained through chemical and mechanical recycling. Given the practical challenges associated with plastic waste recycling, such as incorrect sorting or residual wastes, residual waste must be incinerated. As a result, complete recycling is impractical, and CO2 is inevitably produced while burning plastic waste. This CO2 can be directly captured and utilized in the chemical value chain or stored for later use, avoiding further greenhouse gas emissions. In addition to these sources, utilizing regionally available biomass offers another alternative to fossil feedstocks.
Figure 2 – Vision for realizing net-zero chemical and petrochemical value chains.
However, the actual choice of circular technologies is influenced by regional circumstances. These regional parameters include the availability of renewable energy, fossil and non-fossil feedstocks, financial resources, policies, and regulations aligned to achieve net-zero chemical and petrochemical value chains. In the Arabian Gulf countries, there is a high potential for solar and wind energy as renewable energy sources. The availability of fossil feedstocks, such as crude oil, is abundant and, more importantly, associated with low greenhouse gas emissions during production enabling the potential to reduce emissions immediately. In contrast, non-fossil feedstock resources such as biomass seem to be limited in the Arabian Gulf. Thus, the availability of funding and investment in implementing CCS, plastic recycling, and CCU technologies should be one of the key focus points.
By fostering the transition to renewable electricity, improving the usage of lower-emission fossil feedstock, and focusing on plastic recycling and CCS and CCU technologies, the Arabian Gulf countries can achieve their mid-century net-zero targets between 2050 and 2060.
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