Turning Waste Into Electricity
Jan 24, 2023 7:01 am
These Companies Are Turning Waste Into Electricity Through A Process Called Gasification
3 min read
Each year 2 billion tonnes of waste is produced around the world. This is enough waste to fill garbage trucks that, if placed end-to-end, could circulate the world 24 times. With this number showing no signs of decreasing, it is imperative that a solution is found – and that is where gasification comes in.
Waste incineration or gasification, simply put, is the process of converting solids or liquids into gas through a chemical reaction. Gasification companies are converting non-recyclable waste into syngas, which can then be used to produce hydrogen, diesel, fatty acids, RNG (renewable natural gas), ethanol and electricity. These companies are mainly Sierra Energy, Enerkem, Veolia and China Everbright International.
In addition to the sale of synthetic gas products, these companies generate revenue from collecting waste. Their main customers include municipalities worldwide, office building owners and large multinational corporations.
Sierra Energy calls their method of gasification FastOx gasification. They add oxygen into a furnace where the waste is inserted and burned until it forms syngas. Sierra Energy mentions electricity, hydrogen, diesel, ammonia and construction stones as their end products. They estimate their process to be carbon negative as they claim that the carbon emissions from burning the waste is less than the emissions that they offset. Moreover, Sierra Energy say they use 20% of the electricity produced to power their plant, meaning that they do not rely on the national grid.
China Everbright International uses a process called Grate Furnace Combustion in an incinerator. The furnace, known as an incinerator, is pumped with air in two different places while it burns at 750ᵒC to 1 000ᵒC creating heat and energy in the process. The company says that its plants generate 600kWh per ton of waste, which is enough to power 20 households for 24 hours. The company also has multiple waste incineration plants in China and Vietnam which recycle tens of thousands of tonnes of waste daily, and say that the plants have an estimated 81% rate of efficiency.
Veolia is also a major player in the gasification industry using the same incineration methods as China Everbright International, however Veolia also purifies wastewater into drinking water, and converts sewage sludge into biogas. This is done by processes known as thermal hydrolysis and anaerobic digestion where the waste is chemically broken down into molecules and decomposed by anaerobic microorganisms, in water to then produce the biogas. Veolia says that one of their sites in Germany is 100% electricity efficient, producing electricity for itself using both water and garbage waste. They also stated that one of their plants in France produces 8 000MWh of electricity per year. That is enough electricity to power the average city for 24 hours.
Enerkem is a gasification company that uses a method similar to the one used at Sierra Energy. Enerkem calls its process proprietary thermochemical technology which allows them to recycle the biogenic and non-biogenic carbon in waste materials into syngas. This process only takes 5 minutes and the syngas can be converted into biofuels to then make transportation fuels, solvents & coatings, plastics, and renewable chemicals. Enerkem state that their advanced technology recuperates and recycles carbon circumventing the harmful emissions caused by traditional incineration plants like that of China Everbright International and Veolia. They also argue that their technology is more efficient in producing electricity per ton of waste than traditional incineration plants.
Although gasification is a process that has been around for many decades and helps as a solution not only for the growing waste problem but also for the bid to produce clean energy, it is often criticised for the harmful emissions produced in the process. This is particularly the case for China Everbright International. Incineration causes pollution through the carbon emitted when burning the waste. This is less severe in the gasification processes of Sierra Energy and Enerkem as their technology is more efficient and carbon friendly.
It remains to be seen whether gasification is here to stay or whether a more efficient and cost-effective solution will be found, but gasification is here and should be paid attention to as a present-day solution to our waste, pollution and energy problems.
What do you think of gasification? Is it a helpful way to get rid of waste while generating electricity or is it too harmful to the environment? Share your thoughts by replying to this email.
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