Industry Overview: Waste to Energy

The waste to energy industry utilises several waste treatment methods. Municipal and industrial solid waste is converted into electricity, and sometimes into heat for industrial processing and district heating systems. The main process is of course incineration, but intermediate steps of pyrolysis, gasification, and anaerobic digestion are sometimes used to convert the waste into useful by-products that are then used to generate power through turbines or other equipment. This technology is gaining wide recognition globally as a greener and cleaner form of energy than traditional burning of fossil fuels, and as a means of reducing waste production.

Types of waste to energy

Incineration

Incineration is a waste treatment process that involves the combustion of energy rich substances contained within waste materials, typically at high temperatures around 1000 degrees C. Industrial plants for waste incineration are commonly referred to as waste-to-energy facilities and are often sizeable power stations in their own right. Incineration and other high-temperature waste treatment systems are often described as “thermal treatment”. During the process waste is converted into heat and steam that can be used to drive a turbine in order to generate electricity. This method currently has an efficiency of around 15-29%, although it does have potential for improvements.

Pyrolysis

Pyrolysis is a different waste treatment process where decomposition of solid hydrocarbon wastes, typically plastics, takes place at high temperatures without oxygen present, in an atmosphere of inert gases. This treatment is usually conducted at or above 500 °C, providing enough heat to deconstruct the long chain molecules including bio-polymers into simpler lower mass hydrocarbons.

Gasification

This process is used to make gaseous fuels from heavier fuels and from waste containing combustible material. In this process, carbonaceous substances are converted into carbon dioxide (CO₂), carbon monoxide (CO) and a small amount of hydrogen at high temperature. In this process, gas is generated which is a good source of usable energy. This gas can then be used to produce electricity and heat.

Plasma Arc Gasification

In this process, a plasma torch is used to ionise energy rich material. Syngas is produced which may then be used to make fertiliser or generate electricity. This method is more of a waste disposal technique than a serious means of generating gas, often consuming as much energy as the gas it produces can provide.

Reasons for Waste to Energy

As this technology is gaining wide recognition globally in regards to waste production and the demand for clean energy.

Avoids methane emissions from landfills
Offsets greenhouse gas (GHG) emissions from fossil fuel electrical production
Recovers and recycles valuable resources, such as metals
Produces clean, reliable base-loaded energy and steam
Uses less land per megawatt than other renewable energy sources
Sustainable and steady renewable fuel source (compared to wind and solar)
Destroys chemical waste
Results in low emission levels, typically well below permitted levels
Catalytically destroys nitrogen oxides (NOx), dioxins and furans using an selective catalytic reduction (SCR)

What are the Gas Hazards?

There are many processes to turn waste into energy, these include, biogas plants, refuse use, leachate pool, combustion and heat recovery. All these processes pose gas hazards to those working in these environments.

Within a Biogas Plant, biogas is produced. This is formed when organic materials such as agricultural and food waste are broken down by bacteria in an oxygen-deficient environment. This is a process called anaerobic digestion. When the biogas has been captured, it can be used to produce heat and electricity for engines, microturbines and fuel cells. Clearly, biogas has high methane content as well as substantial hydrogen sulphide (H₂S), and this generates multiple serious gas hazards. (Read our blog for more information on biogas). However, there is an elevated risk of, fire and explosion, confined space hazards, asphyxiation, oxygen depletion and gas poisoning, usually from H₂S or ammonia (NH₃). Workers in a biogas plant must have personal gas detectors that detect and monitor flammable gas, oxygen and toxic gases like H₂S and CO.

Within a refuse collection it is common to find flammable gas methane (CH₄) and toxic gases H₂S, CO and NH₃. This is because refuse bunkers are built several metres underground and gas detectors are usually mounted high up in areas making those detectors hard to service and calibrate. In many cases, a sampling system is a practical solution as air samples can be brought to a convenient location and measured.

Leachate is a liquid that drains (leaches) from an area in which waste is collected, with leachate pools presenting a range of gas hazards. These include the risk of flammable gas (explosion risk), H₂S (poison, corrosion), ammonia (poison, corrosion), CO (poison) and adverse oxygen levels (suffocation). Leachate pool and passageways leading to the leachate pool requiring monitoring of CH₄, H₂S, CO, NH₃, oxygen (O₂) and CO₂. Various gas detectors should be placed along routes to the leachate pool, with output connected to external control panels.

Combustion and heat recovery requires the detection of O₂ and toxic gases sulphur dioxide (SO₂) and CO. These gases all pose a threat to those who work in boiler house areas.

Another process that is classed as a gas hazard is an exhaust air scrubber. The process is hazardous as the flue gas from incineration is highly toxic. This is because it contains pollutants such as nitrogen dioxide (NO₂), SO₂, hydrogen chloride (HCL) and dioxin. NO₂ and SO₂ are major greenhouse gases, while HCL all of these gas types mentioned here are harmful to human health.

To read more on the waste to energy industry, visit our industry page.

Where do Flue Gas Analyzers Fit into the UK Government’s Decarbonisation Plans?

When the UK government announced, in March 2021, that £1 billion of already-allocated funds would be redirected to projects designed to reduce greenhouse gases, the energy sector sat up and listened. And with good reason – as it turned out, £171 million will be allocated to an industrial decarbonisation plan that focuses on hydrogen gas generation and carbon capture and storage technologies.

However, the news extended beyond green energy production and is relevant to domestic and industrial HVAC applications. In a gesture that reflects the role HVAC engineers and manufacturers can play in sustainability, more than £900 million will be spent upgrading public buildings, like schools and hospitals, with greener fittings such as heat pumps, solar panels and insulation, which will reduce carbon dioxide (CO2) emissions.

But where does this leave the individual households and business units that many HVAC staff visit daily? That is a question that several commentators have asked, and it seems that – for now at least – the main drive to reduce the environmental impact of privately-owned heating and plumbing systems will continue to come from the manufacturers, engineers and installers working in the HVAC sector.

And that’s quite a responsibility. According to the Office for National Statistics, in 2020, there were approximately 27.8 million households in the UK; government statistics from 2019 indicate that around 15% of greenhouse gas emissions in the UK (specifically of carbon dioxide, along with methane, F gases and nitrous oxide) came from those residential settings. That’s a lot of excess CO2 to clean up.

So, what can HVAC people do to help decarbonisation?

If they have decent equipment, heating engineers and plumbers can help to reduce that figure by 15%. For example, they are well placed to measure CO2 and other greenhouse gases: while most flue gas analyzers will measure CO2, some can also measure NO/NOx (for example, the Sprint Pro 5 and Sprint Pro 6) well.

A flue gas analyzer that gives a wide range of easy-to-read and interprets measurements allows engineers to see when appliances are not working correctly and whether an upgrade (for example, to a government-subsidised heat pump) might be in order.

This is a pressing need: many households hang onto appliances for as long as possible, even though older appliances tend to be much less environmentally friendly than their modern counterparts. This is bad enough for the environment, but using a malfunctioning older appliance is the worst of all possible outcomes.

A good flue gas analyzer will provide the readings required to convince many customers to decarbonise their homes or businesses more effectively. It will also allow the engineer to fix many problems in more modern and efficient appliances, bringing them back to their original operating standards and protecting the planet once more.

Helping to reach net zero

In late 2021, the UK government set out its plan to reach net-zero emissions by 2050 and every heating engineer in the country has a part to play in that project. While checking flue gases may be an everyday event for many HVAC engineers, the fact remains that household and business emissions account for a substantial proportion of CO2 output and emissions of other dangerous gases. While persuading a single household to operate with lower carbon emissions may not seem like a big deal, the impact can be very substantial when this is scaled up across the country.

Our Partnership with Acutest

Background

Acutest have established themselves as a leading player in test instrument supply, repair and calibration, asset management and bespoke training services. Acutest are a complete solution provider who match to each customer’s need. Their team of external account managers support customers with onsite product demonstration as part of the solution identification process. Serving across sectors including utilities (distribution network operators), sole traders, public sector and white goods. Acutest are a trusted partner to many sectors, who have a diverse customer base including the utilities, street works and rail sectors, facilities maintenance teams, manufacturing, processing and industrial plants as well as individual contractors and electricians.

View on Flue Gas Analyzers

Providing workers within these sectors with the correct equipment is vital, therefore providing these workers with an essential tool is key at Acutest. This tool is used every day; therefore, Anton by Crowcon flue gas analyzers provide an easy-to-use tool that detects CO (Carbon Monoxide) and NO (Nitrogen Oxide).

Working with Crowcon

Acutest have been a long-term partner in which our gas analyzers prevent users from having to store, charge, carry, calibrate and transport multiple devices. Our equipment allows Acutest customers to conduct all critical test measurements with just one high performance, innovative solution. “Our partnership with Acutest has enabled them to supply their customers with a readily available, reliable product as well as customer support. Anton by Crowcon provide innovative tools for every engineer needs and has been a go to on many occasions.”