Green Chemistry

Resources

When environmental impact is being discussed or measured, the emphasis is often on emissions, especially carbon dioxide and other greenhouse gases. Resource use is also important, be it water, land, fossil fuels or renewable resources. Green chemistry places a specific emphasis on renewable resources, and highlights the finite nature of petrochemicals and minerals. This section discusses where chemicals come from and how to manage finite resources.

Dependence on crude oil

Our historical and continued dependence on fossil fuels (crude oil, coal and natural gas) as a key source of carbon and energy in the production of pharmaceuticals is not sustainable. The chemical industry heavily relies on petrochemicals for its products, with resources split 50%-50% between energy and materials, making complete decarbonisation challenging. This dependence has significant environmental implications, including greenhouse gas emissions and the depletion of finite fossil fuel resources. In fact, the chemical industry is responsible for about 5% of global CO2 emissions (Gabrielli et al., 2023). To mitigate the effects of climate change the chemical industry needs to transition from fossil-based to renewable energy, and from fossil-based chemicals to renewable chemicals, as is commensurate with global net-zero strategies (IPCC, 2022) and the UN Sustainable Development Goals (UN, 2015).

Although renewable energy sources such as wind and solar power could replace fossil fuels for energy, a source of renewable materials from which to make pharmaceuticals from is needed. The most promising option is to use biomass, which is converted into useful chemicals in a biorefinery.

The development of biorefineries has the potential to offer sustainable chemical production. For instance, Gabrielli et al. (2023) have illustrated various pathways for net-zero chemical production, comparing conventional approaches to biorefineries as well as direct utilisation of CO2 and emission offsetting by carbon capture. It was found that biorefineries increase pressure on land and water use, but were lower in energy demand than carbon capture and utilisation. This assessment covered commodity chemicals (ammonia, methanol, and plastics). Biorefineries offer more value when it come to specialty chemicals.

The introduction of new biomass-based production methods in Europe encounters significant social, technical, and economic challenges that need to be addressed as well (Bennett, 2012). In particular, cost competitiveness with petrochemicals is a common hurdle. Government intervention will be needed to facilitate the greater adoption of renewable sources of energy and chemicals. Moving forward with their Net Zero Strategy, the United Kingdom's Department for Energy Security & Net Zero has published a Biomass Strategy 2023 Framework to displace fossil fuels and maintain a sustainable approach for biomass uses without compromising food security.  

Elemental sustainability

Within the chemical sector, including pharmaceuticals, there is a heavy reliance on petroleum feedstocks, but also various metals and other elements. The renewable energy revolution is shifting the balance even more towards metals, especially those needed for battery technology. If high demand for critical raw materials, particularly in catalysis and energy storage, goes unabated, we will run out of economically viable sources of essential materials (Hunt et al., 2015). While we continue to mine virgin ores, labour conditions and the resulting environmental pollution and health impacts in some regions have been heavily criticised (Banza Lubaba Nkulu et al., 2018), yet demand only increases. All these factors raise serious questions over the sustainability of many vital elements.

The EU has prioritised critical raw materials based on their economic importance as well as supply risk.

The materials of most concern are those vital to the economy with a high supply risk. The rare earth metals and platinum group metals are unsurprising examples, but also some less glamorous elements such as boron and magnesium also meet this criteria. The EU is entirely reliant on imports of these elements.

• Rare earth elements are used in renewable energy generation (e.g. wind turbines) and energy storage (batteries).

• Platinum group metals (platinum, palladium, ruthenium, rhodium, osmium, and iridium) find use as reaction catalysts and in electronic components.

• Boron is used in magnets and some types of glass.

• Magnesium features in a number of alloys and is used in steel-making.

Palladium, boron, and magnesium also have prominent uses in the chemistry required for pharmaceutical production (Buskes and Blanco, 2020).

Elemental sustainability actions

Broadly speaking, there are two options to improve elemental sustainability. Firstly, we can recycle materials more completely with improved waste collection and with greater efficiency to preserve the quality of those materials. This fits with the objectives of Green Chemistry and a Circular Economy. Secondly, we can replace some elements with more abundant materials, and invent alternative technologies to protect against supply risk and the depletion of finite resources. This is a topic of much interest in the field of catalysis, where conventional metal catalysts tend to be expensive and based on relatively rare elements.