WASTE TO ENERGY (WtoE)
WHAT IS WASTE TO ENERGY?
Waste-to-energy or energy-from-waste is the generation of energy in the form of electricity and/or heat/ waste. W to E is a form of energy recovery. Most W to E processes produce electricity and/or heat directly through combustion or gasification and produce a combustible fuel commodity, such as methane, methanol, ethanol or synthetic gas/fuels.
There are a number of new and emerging technologies that produce energy from waste and other without direct combustion. Many of these technologies have the potential to produce more electric power from the same amount of waste than would be possible by direct combustion. The separation of corrosive components (ash) from the converted fuel allows higher combustion temperatures. Most commonly this will be by use of boilers, gas turbines, internal combustion engines, fuel cells etc. Some methods efficiently convert the energy into liquid or gaseous fuels:
- Gasification (produces combustible gas, hydrogen or synthetic fuels.
- Plasma arc gasification or plasma gasification process (PGP) (produces rich syngas including hydrogen and carbon monoxide usable for fuel cells or generating electricity to drive the plasma arch, usable vitrified silicate and metal ingots, salt and sulphur)
- Pyrolysis (produces combustible tar/bio-oil and chars) Waste Conversion Pyrolysis
- Thermal depolymerization (produces synthetic crude oil, which can be further refined)
- Anaerobic digestion (Bio-gas rich in methane)
- Fermentation production (e.g. ethanol, lactic acid, hydrogen)
- (MBT) Mechanical biological treatment
- MBT + Anaerobic digestion
- MBT to RDF (Refuse Derived Fuel)
Advantages of Waste to Energy
- It helps the UK reduce its dependency on energy imports
- It contributes towards reducing carbon emissions and meeting renewable energy targets
- When used for electricity generation, these technologies have a steady and controllable output, sometimes referred to as providing "baseload” power.
- It has very good sustainability and greenhouse gas saving characteristics, as it makes further use of materials that have already been discarded. This is reflected in the methodology used under the Renewable Energy Directive for assessing carbon and sustainability characteristics. A method of generating energy whilst at the same time incinerating or gasifying waste.
The UK’s energy policy objectives
A quarter of the UK’s existing generating capacity is scheduled to shut down over the next ten years as old coal and nuclear power stations close. Added to that, the UK’s national and international commitments to combat climate change means that energy generation will have to shift to low carbon and renewable energy sources. The UK’s energy policy addresses four key policy objectives:
- Save energy with the Green Deal and support vulnerable consumers. Reduce energy use by households, businesses and the public sector, and help to protect the fuel poor.
- Deliver secure energy on the way to a low carbon energy future. Reform the energy market to ensure that the UK has a diverse, safe, secure and affordable energy system and incentivise low carbon investment and deployment
- Drive ambitious action on climate change at home and abroad. Work for international action to tackle climate change, and work with other Government departments to ensure that we meet UK carbon budgets efficiently and effectively
- Manage our energy legacy responsibly and cost-effectively. Ensure public safety and value for money in the way we manage our nuclear, coal and other energy liabilities
Renewable energy targets
The Renewable Energy Directive (RED) requires the UK to source at least 15% of its total energy from renewables by 2020. To meet this target, the Government has estimated that renewable sources will need to contribute:
- At least 32% of the UK’s electricity, with one-third of this coming from biomass, of which waste forms a part. Currently renewables account for 7.4%
- At least 12% of UK heat requirements. At present this is less than 1%.
- At least 10% of UK road transport fuel requirements. Current renewable fuel production is less than 3%
Renewable Energy Incentives
The Government has introduced a range of financial incentives to encourage the deployment of renewable sources of energy.
The Renewables Obligation (RO)
- Under the RO, electricity suppliers must acquire a growing number of Renewable Obligation Certificates (ROCs) each year, or buy themselves out of this obligation. ROCs are produced by renewable generators, at different rates, according to the technology used. Landfill gas earns ¼ ROC /megawatt hour (MWh) of electricity, whereas a tidal power station in Scotland would earn 5 ROCs. The RO will close in 2017 (following Electricity Market Reform) and replaced by a new incentive: "a Feed in Tariff with Contract for Difference”.
The Renewable Heat Incentive (RHI)
- The RHI is designed to encourage installation of renewable heat generation equipment in the commercial, public and domestic sectors. There is also a tariff for every kilowatt hour (kWh) of biomethane injected into the gas grid. The RHI will pay a set tariff for each kWh of renewable heat produced, for 20 years. There are some inconsistencies for EfW technologies which need to be addressed. The RHI is being introduced in two stages; the first phase from September 2011 and then in October 2012 the scheme will be widened to include more technologies and extended to include households.
The Renewable Transport Fuel Obligation (RTFO)
- The RTFO places an obligation on transport fuel suppliers to substitute a growing percentage of petrol or diesel with biofuels (i.e. bioethanol, biodiesel or biomethane). This will mostly be achieved by blending biofuels with traditional fossil fuels. The obligation currently increases annually until 2013/14 when it reaches 5%. It will need to be increased further to meet the 10% target required under the Renewable Energy Directive. Biofuels can be made from wastes or biomass, and because of their excellent sustainability credentials, they will receive twice the financial incentive compared to other biofuels.
The Small Scale Feed-in Tariff (FiT)
- Small projects, of less than 5 megawatts, qualify for a set tariff for every unit of electricity generated. Of the various EfW technologies, only biogas qualifies. This scheme is aimed at businesses, communities and individuals who have not traditionally engaged in the electricity market.
Where does it come from?
The UK generates approximately 32 million tonnes of municipal (i.e. local authority collected) waste, of which 39% is recycled, 48% is landfilled, and energy Is recovered from the remaining 13% in EfW plants. During the same period approximately58 million tonnes of commercial & industrial waste (C&IW) were generated, of which 50% was recycled and 25% was landfilled. The remaining 25% of C&I waste was subjected to other forms of treatment, with energy recovery in EfW plants contributing a very small fraction.
The Institution of Civil Engineers has estimated that residual wastes could account for as much as 17% of total UK electricity consumption in 2020.
Approximately 65% of residual municipal waste and 61% of residual C&I waste is biomass, i.e. of biological origin. Energy from biomass is renewable energy.
The current proportion of electricity generated from renewables in the UK is 7.4%. Energy recovered from landfill gas contributes roughly one-third. So waste to energy as a whole already provides almost one-half of the UK's renewable energy mix.
The UK produces over 100 million tonnes of wet organic waste each year that could be used to produce biogas, which could represent 4 to 8% of the UK’s 2020 renewable energy target.
WHAT PERSONNEL ARE IN DEMAND WHO SHOULD CONTACT US?
The UK alone has a major resource shortage across all disciplines in the already established energy industries. This means that new and developing technologies need to be resourced from an alternative pool. A new career in W to E can be an interesting and rewarding alternative to the established industries for the right candidate. There are numerous roles available across a diverse range of skillsets. You should contact us if you believe you would like to transfer to this rapidly developing industry, demand means there are generally opportunities regardless of your background.,
Typically the following personnel can transfer with ease with a little assistance:
Project Managers, Project Engineers, Process engineers and designers, Piping engineers and designers, Electrical engineers and designers, Mechanical engineers and designers, Structural engineers and designers, Instrumentation engineers and designers, Safety personnel, Health Physics personnel, Technical Safety engineers, planning engineers, commercial officers, document controllers, HR personnel, admin personnel.