The efficiency of a chemical manufacturing process can be measured by the relative quantities of products and feedstocks, and by how well it utilises energy. Some processes require more energy than others, even if the desired final output or products are the same.
All chemical reactions involve energy. This is typically in the form of heat, making a reaction either exothermic or endothermic, depending on the reactants involved. Higher amounts of energy are required to manufacture larger quantities of reactants (feedstocks).
Generally, there are two ways of increasing efficiency – increasing output while maintaining the input, and decreasing the input while maintaining the output. It mainly boils down to reducing feedstock and energy waste.
In this post:
What is the practice of energy efficiency in chemistry?
Making chemical manufacturing more efficient is one of the twelve principles of green chemistry that many manufacturers are adopting. Not only does this practice ensure compliance with government regulations (if applicable), but it also helps to reduce the cost of production. Energy efficiency always translates into lower energy consumption and cost.
Energy efficiency in chemistry involves various aspects of chemical manufacturing, including direct and indirect factors. Here are some important aspects:
- Type of feedstocks
Unlike in the energy generation sector, the enthalpy – or energy – of the chemicals used to manufacture desired end products is largely preserved. However, an external energy source is also necessary. Chemicals may need to be heated, for example, to react more effectively. In other cases, the reactants may need to be kept under certain pressures.
All of the necessary conditions, especially the required energy input, vary depending on the type of feedstocks and products. Some products require energy-intensive inputs, such as the hydrothermal gasification of cereal straws. The cellulose in cereal straws can be converted into glucose by applying high pressure water vapour and heat. The balanced chemical equation for this reaction is shown below.
(C6H10O5)n + H2O → nC6H12O6
During the partial gasification process of cellulose, the water-soluble products (mainly the sugar subunits like glucose) are hydrolysed if the temperature is below 200 °C.
- Types and number of steps
Most chemical manufacturing processes involve several steps, with complex products typically requiring more steps to manufacture. Generally speaking, the more steps involved, the higher the amount of total energy input. Streamlining the chemical manufacturing process by eliminating one or more of the steps will therefore significantly reduce the overall energy consumption. Alternative processes can be developed to address this issue.
- Machine designs
Some chemical manufacturing plants have outdated machinery and facilities. Replacing these machines can improve the energy efficiency of both the plant itself and its production processes.
New machines are more efficient than older ones (even if they’re the same design or model) and typically require less frequent repairs. Introducing automation in some or all of the vital steps in a chemical plant can also significantly improve energy and production efficiency.
- Better building design
The design of the manufacturing plant building also has an impact on the overall efficiency of chemical manufacturing. For example, if the building is well-insulated, the HVAC system won’t need to consume as much energy to maintain the optimal internal temperature. The energy can then be utilised productively in the manufacturing process. A comfortable working environment also means more productive workers.
Determining the efficiency of a chemical process
Even under ideal conditions, there’s no such thing as 100% energy efficiency as some amount of energy will always be lost. It might be absorbed by the surrounding objects, for example, or wasted as unusable heat.
A chemical reaction can be a straightforward, one-step reaction like the reaction between hydrogen and oxygen to form water when ignited. Alternatively, it can be a complex series of reactions with intermediate byproducts, such as in the case of the Krebs or citric acid cycle.
In cases such as this, the efficiency of a chemical process can be determined through atomic economy, which is another principle of green chemistry. Put simply, the atomic economy aims to maximise the end products from the input materials.
Hence, it can be expressed as the ratio between the atomic mass of the final product and the atomic mass of the atoms in the reactants, multiplied by 100%. A higher ratio means fewer products are wasted and therefore greater efficiency.
Green chemistry energy efficiency
Distillation, purification, electrochemistry, pumping, and pressurising are just some of the essential methods in chemistry and chemical manufacturing. These are used both in small-scale laboratory research experiments, as well as large-scale industrial processes like the fractional distillation of crude oil.
There’s no escaping the fact that industrial-scale chemical manufacturing requires a high amount of energy input. The good news is there are several ways to make chemical processes more energy efficient.
One option is to design methods or processes that don’t require high temperatures. Another way is to use catalysts and enzymes to facilitate reactions. Using renewable energy sources can also help to make processes more energy efficient.
What factors influence energy efficiency?
The two main factors that influence energy efficiency of chemical processes are the raw materials (feedstocks) and the chemical methods themselves.
Other factors include the energy source and design of the machinery and the building or facility.
The Future of Energy Efficiency in the Chemical Industry
The future of energy efficiency in the chemical industry is arguably centred on the use of artificial intelligence (AI). This technology will help solve problems related to complex molecular structures and various configurations that will optimise energy utilisation. AI can also help us to design chemical products that require the least amount of energy to produce.
You can read more about ReAgent’s Environmental Policy on our website.
Original post: Becoming More Energy Efficient in Chemical Manufacturing. No Republication or Redistribution allowed without written consent. Contact ReAgent Chemical Services for more information.
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