A waste to energy feasibility study should start from what the waste can actually do, not from the power plant you hope to build. In a study for a hill-town municipality in South-East Asia, about 200 tonnes a day of mixed waste held roughly 20 MW of thermal energy. But there was no bankable power contract and no grid connection nearby. The recommendation was to produce refuse-derived fuel (RDF) first and add electricity as a second stage.
The challenge: a dump site with no infrastructure
The town’s waste arrived at about 90 tonnes a day and was expected to rise to around 200. It went to an emergency dump on a hilltop with no electricity, no water, no fence and a single unsurfaced road. Waste was routinely burned, partly to recover metals, so much of what lay on site was ash. Roughly twenty people, some with children, were sorting recyclables by hand, and buyers visited the site to purchase materials from a posted price list.
Three consequences followed:
- Landfill gas was ruled out. The waste was shallow, uncapped and largely burned, so it could not support recovery.
- Biogas from anaerobic digestion was also set aside for the moment, because there was no viable use or price for the gas.
- The grid was about 5 km away, and no commercially workable power purchase agreement was available.
The approach: turn the composition into an energy number
No composition data existed for the town, so the study borrowed measured figures from the nearest large city and flagged a local classification study as a later step. The average split by weight was:
| Fraction | Share |
|---|---|
| Organics and wood | 66% |
| Plastics | 15% |
| Paper and cardboard | 6% |
| Inerts and miscellaneous | 4% |
| Textiles | 3.5% |
| Glass, metals, composites and hazardous waste | about 5.5% together |
The study then worked through the arithmetic for a 200 tonne a day stream:
- About 181 tonnes a day (90.5%) was energy-bearing material: organics, paper, plastics and textiles.
- About 19 tonnes a day was inert.
- Overall moisture was around 37%, so roughly 85 tonnes of water a day would have to be driven off, leaving about 115 tonnes of dry mass.
- Using typical heating values for each fraction, the stream held around 20 MW of thermal power. The minimum and maximum composition cases gave about 16 MW and 24 MW.
Plastics are a good illustration. They are about 15% of the waste but supply over half of the thermal energy. Organics are two thirds of the waste but carry most of the water.
Why RDF first
Pyrolysis and gasification are not mass-burn technologies and will not take unsorted waste. They need a prepared fuel. RDF production is therefore a necessary step toward power, and RDF is also a product in its own right. Cement kilns and other industrial users burn RDF, and the study noted that German cement works raised their use of alternative fuels from under 5% of fossil fuel replaced in 1987 to nearly 62% by 2015.
That led to a two-stage plan:
- Stage 1: RDF production. Reception, hand-picking and bulky item removal, a trommel, drying and shredding. Manual sorting was kept as a major part of the process so that the current pickers keep their livelihood.
- Stage 2: power generation. Added when a commercially viable contract for selling electricity exists.
The logic is about bankability. A lender needs revenue it can rely on for the life of the debt. RDF could be sold while the electricity framework was still being negotiated. Compost and recycled materials were not counted in the baseline because their markets were not secured.
The site recommendation
The study’s most important recommendation was to move the waste disposal site. The present location had no services, was unsuitable for a managed facility and was too far from the grid. Finding a new site would be one of the first steps in implementation.
What the study left out, on purpose
The report did not cover finance, a power purchase agreement, methane sales, the site lease or a waste supply agreement. Those are essential to a project and were left for a due-diligence phase. A feasibility study that is clear about what it excludes is easier to rely on.
What to consider for your own project
- Measure the waste. Composition and moisture decide the energy figure. Borrowed data is a placeholder.
- Do the water arithmetic. Drying 85 tonnes a day is a major energy and equipment cost.
- Find your first product. A saleable intermediate such as RDF can fund the road to power.
- Check the off-taker. No power contract means no bankable power plant.
- Consider existing livelihoods. Designing recyclers into the process avoids displacing them.
For UK readers, DEFRA sets out national waste policy and the waste hierarchy.
FAQ
What is refuse-derived fuel?
RDF is a fuel prepared from the combustible fractions of municipal or commercial waste after screening, separation, drying and shredding.
How much energy is in mixed municipal waste?
In this study, 200 tonnes a day held about 20 MW thermal, with a range of 16 to 24 MW depending on composition.
Why not generate power straight away?
The site lacked a grid connection and a workable power purchase agreement, so power revenue could not be relied on yet.
Is landfill gas always an option?
No. It needs deep, capped waste. Shallow, burned waste cannot support gas recovery.
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