Waste-to-Energy (WtE), Carbon Capture & Sequestration (CCS) and Waste Gasification in North America

Driving this uptick in costs for MSW landfilling Worldwide is the fact that China, one of the largest importers of foreign trash, decided since 2018 to place a ban on the importation of plastic waste. Its main suppliers up to that point had been the United States, the EU and Australia. China’s action came as a consequence of many state-side recycling programs transitioning away from requiring consumers to separate paper, plastics, cans, and bottles into today’s more common “single stream,” where it all goes into the same blue bin. As a result, contamination from food and waste has risen, leaving significant amounts of MSW unusable and/or unexportable. In addition, plastic packaging has become increasingly complex, with colors, additives, and multilayer, mixed compositions making it ever more difficult to recycle. Thus, China has now cut off imports of all but the cleanest and highest-grade waste streams, imposing a 99.5% purity standard that most exporters just found impossible to meet. As a result of this decision, costs associated with recycling for municipalities is up whilst revenues associated with recycling have been declining. Furthermore, it is expected that over the coming decade as many as 110 MM tons of plastics will need to find a place for either being recycled or otherwise disposed. To complicate matters, the current economic cold war between the US and China has only worsened the situation. Prior to the Chinese ban, 95 percent of the plastics collected for recycling in the EU and 70 percent of US collections were being sold and shipped to China on the empty (low cost) containers that had originally carried exported Chinese finished products into these markets. This had helped balance the import-export parities and logistical costs significantly, steady state that has been affected by the unilateral Chinese ban on low quality MSW and by the current pandemic and the demand slow-down.

Now, interest in WtE (Waste-to-Energy) solutions has been on the rise due to this situation. In Philadelphia in 2018, for example, the city’s waste processor demanded higher fees for collecting and processing recycled materials. Because of this, the city decided to send half its recyclables to a WtE plant. In parts of Europe, similar situations are taking place as well. And in the United Kingdom, nearly 11 MM tons of waste were burned at WtE plants last year, up 665,000 tons from the previous fiscal year. Since WtE facilities based on the newer technologies are designed to contain and mitigate emissions, the practice has strong proponents for and against among environmentalists and scientists. One of the main causes for concern, still, is that most stateof-the-art incinerators can emit dioxins and other harmful pollutants that have a high probability of ending up in the atmosphere or, worse case, in nearby water reservoirs or migrate into the nearby water tables. Still, this dynamic is lending itself for a potential rebirth in the interest to develop WtE facilties in the United States and Canada.

Particularly since, as explained earlier, much of the waste ready for recycling (non-biogenic) is becoming cross-contaminated with organic waste (biogenic). On top of things, this also ends up having an environmental cost (externality) given that, if this waste ends up in landfills, it will decompose and emit methane (CH4) to the atmosphere. As is well acknowledged, CH4 is a potent, high GWP (global warming potential) gas. And landfills, after all, are the third largest source of methane emissions in the United States (right behind the oil and gas and the intensive cattle/meat production industries). Now, it is a certainty that WtE plants still emit carbon dioxide and potentially other gases. As a way to solve this, some actors have begun to explore ways to minimize even further the environmental footprint of these plants via CCS (Carbon Capture and Sequestration) solutions.

A WtE + CCS Combo to go for your Climate Change and Waste Management woes?

As we mentioned earlier, landfilling and dumping MSW is a rather unsustainable proposition. Not only large areas of land are required, but also these result in significant pollutants accessing the atmosphere (as global warming gases) or the water tables (as heavy metal salts or long-life organic contaminants). Landfill storage sites near major urban centers, unable to cheaply export their MSW due to market and political dynamics, are coming under intense capacity pressure and this is resulting in rising landfill charges by municipalities.

An affordable solution to the challenges included in MSW disposal, rising energy demand by a population and reduction of methane emissions from MSW in landfills comes in the way of Waste-to-Energy (WtE) projects. And the addition of carbon capture and storage (CCS) to WtE has the potential to make waste a zero or even negative emissions energy source, depending on the ratio between biogenic (biological carbon stemming mainly food waste/plant derived) and non-biogenic (nonbiological carbon mainly fossil-fuel derived) waste. When MSW is incinerated, the atmospheric CO2 balance going to the atmosphere is increased mostly due to the non-biogenic waste (the biogenic carbon came from atmospheric CO2 after all involved in the carbon cycle). And as we have explained in the previous section, the percentage of non-biogenic waste is increasing in the MSW streams. This is thus driving a net increase in anthropogenically-derived carbon entering the atmosphere. In a typical carbon balance scenario, for every 100 tons of MSW, 8 of these tons are biogenic carbon materials and 11 tons are non-biogenic carbon materials. The incineration of these material would produce ~ 29 tons of CO2 from biogenic sources and 40 tons of CO2 from non-biogenic.

If a CCS project were able to capture a larger fraction than that from the biogenic carbon materials, then that facility would technically become a net-negative Carbon Dioxide emitter. So, for WtE plants operating on MSW with a significant biogenic component, CCS can provide a pathway to negative atmospheric carbon emissions whilst at the same time producing the power and handling the waste produced by our growing populations and economies. An even more interesting angle to consider is that flue gases from WtE plants are similar to those produced by coal-fired power plants. And since WtE feed streams contain less sulphurated compounds and produce less particulates than coal, less CAPEX is required for pre-CCS gas cleaning processing (compared to that required for CCSing a flue gas from a coal plant). Current developments in CCS process innovation, integration and intensification could potentially lower the capture cost to USD 30-40/ton of CO2 in power generation applications. And furthermore, the United States Treasury department has recently (2018) passed a tax law that may allow for a simpler mechanism to support the financing of the CCS component in joint WtE + CCS projects.