With global warming continuing to have a detrimental impact on the planet we live upon, there are now several different methods of producing energy, some far more environmentally friendly than others. One common technique is to use excess waste to our advantage, through using proven processes that transform the waste into valuable energy. But, how does waste to energy work? And is it really having a positive impact on the earth?
How Does Waste To Energy Work? An Ampower Guide
With a dedication to helping others to use only ‘green’ energy, we are always researching into new ways that both gas and electricity can be produced. It is a well-known fact that we are running out of fossil fuels, which means that it has become more important than ever to find alternatives that will not only provide us with the power we need, but will also prevent a negative impact on the environment. When discussing this topic, waste to energy is a process that often comes up, yet to many, feels somewhat unfamiliar. With this in mind, we have put together a guide to answer the following questions:
Before taking a closer look at how waste to energy works, it is first important to spend time looking at the definition. Although in most cases, the process of generating energy can be somewhat complex, waste to energy is relatively straightforward.
The process is also known as the ‘recovery’ of waste and is the most ecological way to transform waste into energy before it is pumped back into the community. It involves the recycling of waste, as opposed to sending it to a landfill so that it can be converted into a useful everyday resource. This is completed by burning the excess waste at a high temperature to ensure that any chemicals trapped inside are destroyed. The heat produced is then converted into energy, and in return, the steam will begin to drive a turbine that produces electricity. As well as electricity, waste to energy also creates clean water, metals and construction materials.
While opting for using power generated through the waste to energy process is far more environmentally friendly than sending to the landfill, it is not the ‘greenest’ solution. To determine how efficient an energy source, the waste hierarchy tool can be used. Waste hierarchy places energy generation methods into an order from the most ecological to the least, including the following:
- Prevention = This is the most favourable option and involves preventing waste from being produced in the first place.
- Reuse = Sometimes known as ‘minimisation’, this relates to anything that you give a second life. For example, donating old clothing to charity or upcycling furniture.
- Recycle = When it comes to throwing away food or plastic, for instance, recycling is the best option as it means that these materials can be reprocessed.
- Recovery = As mentioned above, waste to energy falls into the recovery category, sometimes involving the incineration of waste.
- Disposal = The least favourable option is the disposal of waste, which relates to landfills and other finalist methods.
Now that you are familiarised with what waste to energy is, you can begin to delve deeper into the different types. There are several methods of generating energy solely through the use of waste, and these are the following:
Combustion is the technical word for burning and is one of the most common examples of waste to energy. We are all more than aware of the environmental impact that burning fossil fuels can cause and waste to energy combustion can be equally as harmful.
During combustion, much like the process mentioned above, the waste is incinerated at extreme temperatures, which burns it until it is reduced to just hot gas and ash. It is the heat from the gas that is then used to generate power, which is a similar process to those used by nuclear plants. Although this process itself is not the most energy-efficient, in many cases, any excess hot gas is redistributed to local business to use, which does help to boost its efficiency. Any ash that is leftover is then put through a second process, which uses magnets to draw out any metals which can be recycled. The remaining ash can be used as an aggregate for those in the construction industry, but if this is not possible, the last option is to send it to a landfill site.
Gasification is a ‘greener’ alternative to combustion and while it has only recently started to be used in the waste to energy world, is a process that has been around for many years. As opposed to burning waste, gasification involves turning it into gas, hence the name. In this instance, the process is more economical because it creates a high-quality syngas, which can then be transformed into other sources of energy, such as electricity, diesel and hydrogen. Syngas is also known as a ‘clean gas’ and is similar to gases that are naturally produced.
During gasification, the waste enters the process and is combined with a high-controlled amount of oxygen or steam. This causes a reaction, which produces a synthetic gas mixture of carbon monoxide, hydrogen and other elements. As unlike its alternatives, no energy generated through gasification will be wasted because any excess not used for electricity, can be used for fertilisers, chemicals and consumer products.
Pyrolysis is another method of extracting energy from waste and involves decomposing a substance through thermal techniques. The process is completed in a non-reactive atmosphere at maintained, high temperatures, usually between 300 and 850-degree centigrade. Although the process is somewhat similar to combustion, pyrolysis does not involve oxygen, which means that it has lower emissions and is more ecological. Much like gasification, pyrolysis produces syngas; however, the difference is that you are also left with a solid residue, which is commonly known as char.
While pyrolysis is far more eco-friendly than combustion and many compare the energy produced to those generated through renewable sources, it cannot technically be considered as renewable energy. This is because chemicals are released, and CO2 is produced, which mean that it does impact the environment, albeit less than its alternatives.
Anaerobic digestion is a super common example of waste to energy, involving the breakdown of organic matter, which can be anything from animal to food waste. During the conversion process, the waste is often blended into a liquid before being placed into a storage tank. In small batches, the liquid waste is transferred into an anaerobic digester, which is an environment that involves no oxygen, hence the name anaerobic. This liquid is then heated and mixed inside the digester for just over a month, which allows plenty of time for methane-rich biogas to be produced. Once this process is complete, there will be three valuable resources generated; these are:
- Biogas – Biogas is a renewable energy source which means that it is classed as ‘green’ power. In fact, here at Ampower, biogas plant is one of the sources we use for our home gas plans and business gas plans.
- Liquid Digestate – The liquid digestate is always cleaned and then transferred back to the sewers.
- Solid Digestate – This is given back to agricultural sectors and used for fertiliser.
When on the topic of anaerobic digestion, one important aspect to highlight is that the process is not the same as producing compost. Although it is very similar, anaerobic digestion does not involve any oxygen, whereas, if you were to begin composting from home, there would be oxygen present. This doesn’t mean that composting is less ecological than anaerobic digestion as it is a fantastic way that you can optimise your food waste. It is also hugely beneficial to your garden as homemade compost helps to balance the PH levels of your soil, as well as maintaining moisture and improving soil structure, rewarding you with a healthier garden. If you are interested in composting, then you can find a full guide on the RHS website.
Landfill Gas Recovery
The last example of waste to energy that we are going to discuss is landfill gas recovery; this is an effective way to ensure that any waste that does find its way into the landfill site can be as environmentally friendly as possible. Once waste reaches the landfill site, it starts to decompose, which produces methane. Around half of the methane is then used for landfill gas, which is then collected using an underground network of pipes. These pipes feed their way through to a compression system, where the gas is dewatered, pressurised and filtered to ensure that it is clean. Together, these allow the gas to be transformed into renewable energy fuel. This process takes just a few seconds, which makes it an incredibly popular way to succeed in waste management.
Having run through several different methods of generating energy from waste, you may be wondering whether this method is good for the environment. This question does not have a precise answer as how ‘green’ the energy is does depend on the process that has been used. For example, if you were to choose the combustion route, you will still be producing harmful chemicals and therefore, will do just as much harm as burning fossil fuels. Whereas, anaerobic digestion, on the other hand, is now classed as a renewable energy source, which means that you will be taking an ecological approach.
To ensure that you have the peace of mind that you are choosing only ‘green’ energy, it is essential to only opt for working with energy providers who are committed to using renewable sources. Whether you are a commercial or domestic property owner, you can have control over the energy that you use in your home, even if you are not producing it independently. At Ampower, our goal is to become a 100% ‘green’ energy provider through using generators such as biogas for gas plans, along with solar, wind, tidal and hydropower for our home and business electricity plans. If you would like more information on any of our tariffs or have any questions regarding the renewable energy we use, please do not hesitate to get in touch.
Waste To Energy Made Easy!
We hope that our guide has helped you to familiarise yourself with not only how waste to energy works, but also the various methods of energy production that you can consider. Being mindful of the energy you use is one of the most effective ways that you can begin to take a more environmentally friendly approach and in return, lower your carbon footprint.