Green Energy out of Waste Oil – Thames Water London

WHEN: Ongoing, Starting 2015.
WASTE MANAGEMENT HIERARCHY: Recycling: Reuse – Reprocessing    TYPE OF INSTRUMENT: Awareness rising and Voluntary
WASTE STREAMS: WASTE OIL (FOGs – fat, oil and grease) and Sewage Sludge (additionally)

About: In 2015, the UK-based green utility company 2OC set up a combined heat and intelligent power (CHiP) plant at Beckton (east London). The main source of fuel for the plant consists in fats, oils and greases (FOGs) which are thrown away by households and restaurants.

The plant has an annual output of 130GWh of electricity, while the installed capacity is 19MW. It operates at an electrical efficiency of more than 65% and provides power for about 40,000 households.

The plant was constructed on 2OC’s own land near Thames Water’s desalination plant and sewage treatment works site and became operational in the second half of 2015.

Thames Water (Britain’s biggest water company, serving 15 million customers across London and the Thames Valley) is authorized to collect animal fat and waste vegetable oils from households, restaurants and food product manufacturers, and supplies the collected oil waste to the Beckton plant. It supplies 300 tonnes of FOGs/day to the plant, which forms half of the fuel requirement.

The Beckton sewage works, managed by Thames Water, is now Europe’s largest, and right near it, is the world’s first industrial-scale plant run on FOGs. The plant, developed by 2OC for a 20-year contract, £200m deal with Thames Water, provides renewable power and heat to the Beckton sewage works. The plant is also compatible to use other renewable fuels such as bio-methane.

Photo Source: Thames Water


Producing and supplying green energy (including out of wastewater) is one of the main objectives of Thames Water, which aspires to maximize the recovery of energy and resources from wastewater and to reduce the need to dispose of biosolids to land or by incineration. Thus, as results from its annual report for 2017/2018, the priorities of the utility company are :

– Reduce the number of pollution incidents to zero in the medium to long term
– Become 4 star rated under the Environmental Performance Assessment (EPA) framework
– Maximize the potential of innovation to increase the amount of energy produced, targeting a further 17% increase in all renewable energy generation to 517GWh by 2025
– Extract and recycle 100% of energy and materials from the wastewater in the region
– Protect and enhance biodiversity during its activities through continued investment at their sites.


Apart from the plant facility, one of the main resources is the sewage team, out of which sewage experts and “Sewper Heroes” must be mentioned, the last ones clearing over 85,000 blockages/year (all sort of blockages, including those generated by FOGs).

Also, the campaigns and guidance provided by the utility company is crucial in educating people and commercial waste oil generators to eliminate or, at least, reduce the FOGs thrown in the sewage, especially given the statistics (1/3 of Thames Water customers still believe putting oil down the sink is the best way of dealing with it, and are not aware that these oil can solidify in the sewers leading to costly blockages ).

Through informational reports and articles published on its website and media, Thames Water carries out an educational activity, aiming at raising awareness of both people and restaurants on the causes and effects of sewage blockages caused by FOGs but also provides simple measures and tips & tricks for the storage and disposal of FOGs:
– Tips for kitchens and bathrooms
– Information about blockage causes (mainly – fat, oil, food leftover, wipes and sanitary items).


The FOGs based plant from Beckton supplies 130GWh of electricity a year – more than half of which comes from urban fat (30 tonnes/day), collected from restaurants and drains then liquified. The rest of the power plant’s fuel will come from tallow – animal fat – and waste vegetable oils; no virgin oils from field or plantation-grown crops are used.

Combining wind and solar power with electricity generated from sewage, Thames Water generated 293 GWh of energy in 2017-2018, equivalent to £30 million/year in energy costs. It also reduced the greenhouse gas emissions by 112.6 kTCO2e.

Progress in 2017/18:
– 7% year-on-year reduction in pollution incidents
– Produced 286GWh of electricity from sewage, company’s record performance
– Self-generated 1/5 of company’s electricity needs (an increase of 12%)
– Walthamstow Wetlands, an operational site, opened as Europe’s largest urban wetland nature reserve
– Built the first full-scale sustainable Nereda plant in the UK, to improve the quality of the water being returned to the environment in a more energy efficient way. It purifies water using aerobic granular biomass
– Sponsored a multi-award winning ‘water efficient’ garden at the RHS Chelsea Flower Show.

Also, company’s wastewater operations consumption of self-generated energy has risen to 38%, up 5% on last year. During this regulatory period, they have reduced their net consumption of grid electricity by 140 GWh.

A peculiar and unexpected situation happened in September 2017, which led to both a case study and a public event. Thames Water uncovered a 130 – tonne mass of fat and un-flushable debris in the tunnels of Whitechapel. This ‘fatberg’ was exhibited in the museum of London from February until July in 2018.

Urban metabolism relevance

Environmental impact:

Many cities around the world are at daily risk of suffering a municipal coronary in their sewerage networks, leading to a high environmental impact (by causing flooding and pollution).

Particularly, FOGs (fat, oil and grease) cause major problems to drains and sewers. When they are disposed of down kitchen sinks or drains, they cause blockages; when they enter rainwater pipes or gullies, they cause pollution in streams and rivers.

In London area, each year, the Thames Water sewage team clears around 85,000 blockages, most of these being caused by cooking fats and oils, which congeal in the sewers forming a thick layer around the pipe. This prevents sewage from flowing and can cause it to back up, especially when products such as wet wipes and sanitary items – which were not designed to be flushed – mix with the fat and set hard forming a solid obstruction, called a “fatberg”.

„Fatbergs” can have a catastrophic impact on the natural environment and the lives of customers when they form concrete-like obstructions in sewer pipes forcing sewage back where it came from. Every year, Thames Water spends about £20 million to clear blockages, predominantly made up of wet wipes and cooking oil, instead of better spending this money for improving network resilience.

Main generators:

One of the main responsible for waste oil generation is the HoReCa sector, mainly due to eating habits that have been changed during time. People are eating out much more frequently than they did in the past and the number of food outlets is increasing. Fat, oil and grease in liquid form may not appear to be harmful, but as it cools it congeals and hardens. It sticks to the inner lining of drainage pipes and restricts the wastewater flow causing the pipes to block. Using detergents or bleach may appear to help but this is only temporary as the mixture soon turns back to thick or solid fat.


a) Proper waste oil storage
Waste oil generated at home, but mainly in HoReCa units, comes from sources such as deep fat fryers, woks, frying pans and baking trays. Waste oil and fat should be collected in an air-tight container to prevent odors and rats. The container should be stored in a secure area, clear of all drains, to prevent spills and leakages.

b) Grease traps/grease interceptors
Grease traps are specially designed units which are placed in drain pipes to separate the fat, oil and grease from the rest of the wastewater. The wastewater then continues to flow to the sewage works for treatment while the grease is retained in the trap to be collected by a licensed waste oil collector at regular intervals. These units can be highly effective if they are correctly installed, serviced and maintained.


Producing green energy out of waste oil is an innovative technology and is in a continuous expansion in the past years in many countries.

Engaged participatory processes

Flooding and blockages generated by FOGs are a major problem for citizens, companies (mainly restaurants and catering units) and institutions, as well. Therefore, the involvement of all these stakeholders is crucial for the success of the waste oil collection and usage as bio-fuel.

Thames Water works together with their customers and stakeholders, mainly to change the waste disposal behaviors. The company also works with council environmental health departments to get their backing in targeting campaigns to specific hotspots.

Also, Thames Water applies to public information to educate people on the consequences of “sewer abuse”. For example, when the big fatberg (Whitechapel fatberg) has been discovered in September 2017, Thames Water informed the people that fatbergs are responsible for huge expenses (around £1 million a month to clear ), due to the need to dig up roads to fix broken sewers. Ongoing publicity for stories like this will decrease the number of blockages, helping customers to prevent their expenses and avoiding environment pollution.

A particular attention is paid by Thames Water to campaigns made for awareness rising in HoReCa sector.

A campaign to reduce sewer-blocking fatbergs has been carried out starting February 2017. Under this campaign, more than 800 food outlets across London and Thames Valley received face-to-face waste disposal advice from Thames Water experts. The campaign started in the areas identified as sewer blockage hotspots. As part of the visits, the Thames Water engineers helped owners and kitchen workers understand the consequences of putting food waste, fat, oil and grease down the sink and drain.

Following this campaign, several fast food outlets in hotspots like Reading, Hounslow and Dartford have also installed grease trapping equipment and adapted their processes to help in the ongoing fight against fatbergs.

Also, a very useful booklet has been issued by Thames Water to help businesses get rid
of fats, oils, greases and leftover food correctly.

Thames Water is closely engaged with the communities, even in other environmental and charitable actions. Through the “Time to Give” programme, all company’s employees receive 2 days/year to volunteer in different ways for charities that operate in the communities they serve. From litter picks to upcycling furniture for charities, employees spent 6,393 hours taking part in 1,040 volunteering opportunities in 2017-2018.

Sustainability and replicability

Even there is still room for expanding this good practice, programs similar to Thames Water waste oil recycling are run in UK and other countries:

– In New York and Dallas there are programmes to teach residents and businesses about the dos and don’ts of discarding FOGs – “Cease the Grease” .
– In Newcastle, Northumbrian Water gives the same message a more upbeat spin with its Love Your Drain campaign and mascot, Dwaine Pipe.
– Scottish Water is trailing a six-month pilot project in St Andrews to combat fatbergs and reduce the risk of major flooding and pollution. The project aims to substantially reduce the number of blockages in the sewer system caused by FOG – being incorrectly disposed of by businesses which serve food. If the project succeeds in cutting blockages in St Andrews due to FOG, it will be rolled out to other parts of Scotland.

Collected waste oil can be used for bio-diesel production – transport fuel or incineration for the generation of electricity – reducing the dependency on landfill sites and the use of fossil fuels for energy generation. In this respect, governments should support these activities, through financial and fiscal advantages.


Success Factors

Awareness campaigns are the most important success factor, as the method of disposing of grease properly is simple by itself: by pouring the hot liquid into a coffee can, tuna can or any other sealed container that will not burn or melt. Once the liquid has cooled, the container can be discarded with the rest of the garbage. Dishes should be cleared of oil, grease and food scraps with paper towels before they are washed.

For example, after 4 months of food outlets campaign, many of food units representatives admitted they have improved their practices following the advice given by Thames Water and are already reaping the benefits. Thames Water launched this campaign following a successful pilot in Oxford which revealed 95% of food establishments visited were contributing to sewer blockages by having inadequate or no kitchen grease management. Only 5% had the correct-sized grease traps installed and properly maintained.

In UK, if in the past, food outlets were often paid for their waste oil, which could then be used as a high energy diet for livestock, due to a change in legislation, now the oil must be collected commercially for disposal or recycling.

Also, sewage waste turns to be a valuable resource and its potential can be maximized by turning it into fuel. Thames Water is an industry leader in the production of energy from sewage sludge.



Waste, Resources, Innovation.

Key Challenges


The number of blockages and pollution incidents relating to fat, oil and grease are increasing. There are approximately 200,000 sewer blockages throughout the UK every year of which up to 75% are caused by fat, oil and grease.

Clearing these blockages costs millions of pounds a year which is reflected in customers’ bills. Businesses also risk blocking their own drainage systems, which results in extra costs being incurred in clean-up efforts.

These fat blockages can result in sewer flooding, odor problems and the risk of rat infestations, both near and beyond customer’s premises.

Therefore, key challenges are:
– Uneducated people and business representatives
– Increasing population
– High density of catering and restaurants number in a region (risk area)
– Utility company ownership can also be a challenge in a community. Many cities require every business that generates FOGs to install grease traps, to block the substances from reaching the sewer lines.

Unfortunately, privatized utilities – like Thames Water – often have no right to inspect hotels and restaurants to make sure they’ve installed traps, or how they’re disposing of the FOGs they catch.




For more information, please contact the implementing body.

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