Waste to Energy

Project Drawdown defines waste-to-energy as the combustion of waste and conversion to electricity and usable heat in waste-to-energy plants. This solution replaces conventional electricity-generating technologies such as coal, oil, and natural gas power plants.

Waste-to-energy reduces greenhouse gas emissions in many cases, though the magnitude of that reduction varies substantially depending on the baseline used for comparison. Key considerations in waste-to-energy’s case include: the caloric content of combusted waste; its methane generation potential (were it to be landfilled); likely alternative waste disposal pathways; and the emissions intensity of electricity and/or heat being displaced by that generated by the waste-to-energy process.

Waste-to-energy has seen wide adoption in Europe, the United States, and Japan, and adoption is growing rapidly in China. Organisation for Economic Co-operation and Development (OECD) countries are most likely to see significant growth in its market penetration moving forward, because the primary barriers to entry for waste-to-energy are high capital cost (in part due to high-cost pollution control technologies, which are essential in mitigating potential adverse public health impacts) and the reliable availability of municipal solid waste with a high caloric heating value. Waste-to-energy adoption will have the largest climate impact when it displaces both landfill disposal (particularly with low methane capture) and carbon-intensive power generation (i.e., coal, natural gas, and oil combustion).

Methodology

Waste-to-energy adoption is presented in two ways: in terawatt-hours of electricity generation, and in tons of waste produced. Both types of presentations are used in the adoption prognostications.

Total Addressable Market

Two total addressable markets were developed for this sector solution, supported on lower and higher climate emissions mitigation targets linked to different levels of electricity demand and renewable energy sources integration. The total addressable market for waste-to-energy is based on projected global electricity generation from 2020 to 2050. Current adoption[1] was estimated at 0.54 percent of generation (i.e.,142 terawatt-hours).

Adoption Scenarios

Impacts of increased adoption of waste-to-energy from 2020 to 2050 were generated based on two growth scenarios. These were assessed in comparison to a Reference Scenario, in which the solution’s market share was fixed at the current levels.

• Scenario 1: This scenario is built upon the average yearly adoption of six custom scenarios derived from conservative adoption scenarios from the IEA (2016) ETP 4DS and 6DS, Greenpeace (2015)  Energy [R]evolution and Advanced Energy [R]evolution scenarios, and different scenarios supported on the methodology suggested by Monni et al. (2006), applying different caps to waste to energy use. This results in a 1.1. percent share of the total electricity generation portfolio in 2050, with 493 terawatt-hours of electricity generated.
• Scenario 2: This scenario is built upon the average yearly adoption of two custom scenarios derived from ambitious solution adoption trajectories, i.e., IEA (2016) ETP 2DS and IEA (2016)  ETP Annex 1 methodology. This results in a 0.3  percent share of the total electricity generation portfolio in 2050, with 210 terawatt-hours of electricity generated.

The resulting adoptions are adjusted on the waste cluster integration model due to waste feedstock limitations. Tons of waste used in waste-to-energy processes are converted to terawatt-hours of electricity produced by multiplying an estimated heating value of waste and average efficiency of waste-to-energy plants.

The uncertainty associated with the future adoption of waste-to-energy is linked to other waste management solutions: landfill methane capture, large methane digesters, recycling, and composting could affect the balance of available waste for each solution. Thus, the Scenario 2s have lower adoption trajectories of waste-to-energy than the Scenario 1.

Emissions Model

The result of the assessment is a regionally explicit forecast of waste-to-energy adoption and climate impacts, in terms of both avoided methane and carbon dioxide emissions. Landfill methane emission rates are estimated using the first-order decay method recommended by the IPCC in order to estimate total emissions reduction for waste-to-energy in comparison with sending the waste to a landfill.

Financial Model

The financial inputs used in the model assume an average installation cost of US$6795 per kilowatt.[2] Since waste-to-energy using incineration is a mature technology that has been in widespread use in OECD countries for many decades, a learning rate of 2 percent is applied to first costs. An average capacity factor of 77 percent is used for waste-to-energy plants from historical data, compared to 57 percent for conventional technologies. Fixed operation and maintenance costs of US$304.9 per kilowatt are considered for waste to energy systems, compared to US$34.7 per kilowatt for the conventional technologies. variable operation and maintenance costs of

Integration

Through the process of integrating waste to energy with other solutions, the total addressable markets were adjusted to account for reduced demand resulting from the growth of more energy-efficient technologies,[3] as well as increased electrification from other solutions like electric cars and high-speed rail. Grid emissions factors were calculated based on the annual mix of different electricity generating technologies over time. Emissions factors for each technology were determined through a meta-analysis of multiple sources, accounting for direct and indirect emissions.

Results

The results for Scenario 1 show that through increased global adoption of waste-to-energy from 2020 to 2050, 73 gigawatts of waste-to-energy plants can be installed globally, increasing the electricity generation market share for this technology from 0.54 percent to 1.1 percent. This will result in the avoided emissions of 2.0 gigatons of carbon dioxide-equivalent of greenhouse gases. The net cost compared with the Reference Scenario would be US$134.7 billion from 2020 to 2050, and around US$96.7 billion of negative lifetime savings for waste-to-energy plants.

Due to integration with other waste management solutions covered in Project Drawdown, the solution adoption is lower in the Scenario 2 since more preferred solutions are increasingly adopted. Nevertheless due to the double counting methodology and the higher total addressable market in Scenario 2, it results on higher emission reductions over 2020–2050 of 3.0 gigatons of carbon dioxide-equivalent.

Discussion

While preferable to landfilling, waste-to-energy is seen as a bridge technology before other preferable waste management options become fully possible.

Promotion of waste-to-energy will be most successful where waste disposal and electricity costs are high, and where capital is readily available. Waste-to-energy should be promoted appropriately in each region’s context, within a broader framework of integrated solid waste management. This is all the more important given the potentially significant public health risk that insufficiently regulated waste-to-energy can pose (and has historically posed) to nearby communities. When appropriately strict pollution controls are in place, and when landfilling is a likely waste disposal alternative, waste-to-energy will nonetheless continue to provide an opportunity for societally beneficial greenhouse gas emissions reduction.

New waste-to-energy research in Europe and the United States is relatively sparse now, as a result of the technology’s maturity. More active research is ongoing, particularly in East Asia. In general, research resources are more heavily allocated to new technologies such as gasification, pyrolysis, and plasma-arc gasification (as opposed to combustion). While these technologies are common in Japan, they have yet to become mainstream in any other part of the world.