Because of their multifaceted expertise, chemical engineers have been at the forefront of innovation in the generation of energy. They have devised methods for use of renewable as well as nonrenewable feedstocks. A vast array of chemical-engineering principles is used to generate electricity and to produce different types of fuel for transportation, industrial, and residential purposes.
Crude oil, or petroleum, is of little use in its raw state. Its value to society lies in the broad slate of products that can be created from it. Refineries use complex chemical separation and conversion processes to turn crude oil into gasoline, diesel and jet fuel, kerosene, lubricating oils, and numerous other end products.
Producing Energy from Fossil Fuels
The imaginative and pioneering efforts of chemical engineers have been responsible for the development of a complex array of chemical conversion processes. These processes are used to create physical changes in crude oil and natural gas, which yield the many end products we rely on today. These products run the gamut from gasoline and diesel fuel, to kerosene, lubricating oils, waxes, and asphalt, as well as many intermediate petrochemical products.
Chemical conversion processes
Some of the important chemical process operations instrumental in modern-day refining include
- Thermal cracking,
- Fluid catalytic cracking,
- Hydrocracking, and
This list is merely representative, as the total number of petroleum-refining operations to which chemical engineers have made significant contributions is very large.
Refining the refineries
The chemical-engineering community is constantly working to modify and improve the petroleum-refining processes. Their objectives are to
- Achieve higher conversion rates and greater yields,
- Improve overall energy efficiency,
- Produce cleaner fuels,
- Reduce refinery emissions, and
- Reduce operating costs.
Synthetic liquid fuels
In order to reduce our dependence on foreign oil, chemical engineers have been working vigorously to develop, scale up, and commercialize new processes to produce synthetic liquid fuels. Coal and oil shale are used as the primary feedstocks, and both are still in abundant supply in the United States.
Working on Alternatives
North America relies heavily on imported foreign crude oil for use in its refineries. Vulnerable to global instability, these supplies are subject to considerable price volatility and availability issues. For these reasons chemical engineers have focused their expertise on the development of different processes that would use alternative feedstocks. Rather than relying on conventional crude oil and natural gas, the goal is to use coal and oil shale to produce synthetic liquid fuels.
Synthetic fuel production
Essentially two routes are used to produce synthetic liquid fuels:
- The Bergius process, which uses hydrogen and brown or soft coal, and
- The Fischer-Tropsch process, which starts with carbon monoxide and hydrogen.
Chemical engineers have been instrumental in advancing both of these technologies.
Chemical engineers are involved with developing technologies to convert renewable biomaterials into electricity and transportation fuels, just as they have been with nonrenewable fossil fuels. Corn and sugar are now widely used to produce ethanol, a gasoline substitute. And soybeans are being used to produce diesel fuel.
Power from Plants
Biomass is plant material—fast-growing trees and grasses, grains, corn, sugar cane, wood scrap, even woody leaves and stalks and garbage. It is a sun-dependent renewable feedstock that can be used to produce biofuel. This type of fuel can be converted into gaseous and liquid fuels for electric power generation and automobile propulsion.
Bushels into barrels
Chemical engineers have been instrumental in the development and commercialization of processes that allow bushels of biomass to be turned into barrels of fuel. They will continue to play an increasingly important role in the quest to achieve greater energy self-sufficiency with more environmentally friendly, renewable sources of fuel and electricity.
Made by fermenting biomass rich in carbohydrates (starches and sugars), ethanol is a gasoline-like alcohol. It is currently finding wide use in the production of a gasoline ethanol mixture, raising octane while reducing pollutants. With engine modifications it can be used as a direct gasoline substitute.
Made from vegetable oils, animal fat, and even recycled cooking grease, biodiesel is a functional alternative to conventional diesel. Many diesel engines that can use this renewable fuel with no change in performance are already available. Biodiesel is also inherently cleaner than fossil-fuel diesel.
Electricity from biomass
Renewable feedstocks, such as forest and agriculture residues, landfill gases, and municipal wastes, can be used to generate electricity. Four basic methods are now being used:
- Direct firing, where biomass is burned directly;
- Co-firing, where biomass is mixed with fossil fuels;
- Biomass gasification that turns biomass into synthetic gas; and
- Anaerobic digestion that promotes biomass decay to produce methane, the principal component of the natural gas we burn today.
Electricity from coal
Coal fueled the Industrial Revolution and for years was the primary power-plant fuel. Chemical engineers have been working to provide greener options for generating electricity from coal. Some power plants now generate power by using coal gasification as an intermediate step instead of coal combustion, with significant environmental benefits.
Making coal greener
In an effort to provide greener options for generating electricity from coal, chemical engineers have made great strides. They have achieved significant environmental improvements with the development of integrated combined-cycle gasification (IGCC) power plants. These plants generate power first by producing gas through coal gasification and then by converting the gas to power, rather than by using traditional coal combustion. Pollutants are lowered as is water consumption.
In IGCC power plants coal is first turned into a synthetic gas. The syngas is cleaned to remove unwanted pollutants and then burned in a gas turbine. The exhaust from the primary turbine is used to create steam for a secondary turbine that generates additional electricity.