Carbon Capture and Storage (CCS) has been a crucial strand of the Intergovernmental Panel on Climate Change’s (IPCC) recommendations on how to limit global warming to a manageable level. Although CCS technology has borne its detractors along the way, largely because of sequestration’s inadvertent use in the extraction of more fossil fuels, the weight of opinion has landed on the side of widespread adoption of CCS in the global fight against climate change. So why then are we seeing heated debate around the application of CCS in Waste To Energy (WTE) plants?
The notion of capturing the CO2 emitted while burning Municipal Solid Waste (MSW) to generate much-needed electricity, seems like a no brainer. However, considered in the context of a national, and indeed a global push toward reducing the amount of MSW we create, we can understand that CCS can be viewed as a solution to a problem we ought to strive not to create in the first place. Thus, there is a concern that the goals of a circular economy and the demand for MSW to stoke WTE incinerators are fundamentally at odds.
What Is Waste To Energy?
Landfilling MSW is incredibly harmful to the environment because it produces methane, a dangerous greenhouse gas (GHG) with an outsized contribution to global warming. The amount of MSW left to decompose in landfill has long been countered by diverting it to incineration plants. But the last few decades have seen the growth of Waste To Energy (WTE) plants, where MSW is combusted to produce electricity for homes and businesses. In 2018, 12% of MSW produced in the US (292 million tons) was burned in WTE plants to generate power.
The process involves burning mixed garbage to heat water, the steam from which then powers a turbine generator which outputs electricity. Some of the waste filtered out during the process can be used as aggregate for road beds and rail embankments, while metals like iron, steel and copper can be extracted with magnets and take the place of virgin raw materials in industry. However, the water vapor released into the atmosphere from the process contains a lot of CO2 and directly contributes to global warming. The vapor also contains significant quantities of toxins and noxious elements like nitrogen oxides. Proponents of WTE argue that the downsides are outweighed by the quantity of waste removed from landfill.
Although energy derived from MSW is a mere fraction of the total US power supply (0.2% compared to 60.8% from fossil fuels), its impact on the environment is far from negligible. To put WTE emissions into context we can look to the EU, where in 2019, the entire continent’s incinerators emitted 52 million tonnes of fossil CO2 – more than the sum total GHG emissions of Portugal in a year. Amidst the obvious benefits of cutting down on the MSW we send to landfill and the harmful carbon emissions from the WTE plants that process it, a double edged sword begins to take shape.
This is where carbon capture and storage is proposed as the solution. If the carbon emitted by WTE plants can be negated altogether, the WTE industry can become a carbon sink, i.e. a carbon negative activity. This would be a significant boost to the Biden administration’s ambition to cut US carbon emissions by 52% by 2030 (from 2005 levels). But before we delve into how to balance these concerns, let’s take a beat to understand CCS more broadly.
What Is Carbon Capture And Storage?
The most recent IPCC report ‘Mitigation of Climate Change’ concludes that carbon capture and storage is a crucial strategy to limit us to 1.5 degrees of warming. In practice, CCS means intervening either at the source of carbon emissions or pulling CO2 directly from the atmosphere later on. The former, Point Source Capture, is considered the more effective and cost-efficient method of the two. In this scenario carbon is captured as it is emitted, for example at factories or power plants. Direct Air Capture, in which carbon is sucked from the atmosphere after the fact, has many more barriers to proliferation, including prohibitively high cost and a technology in its infancy. Swiss outfit Climeworks is one of the few companies leading the way in that field but Biden’s administration recently made their own landmark investment in the field.
Carbon captured with either method must then be stored, usually within depleted oil or gas reservoirs underground or beneath the sea, where it can be held for thousands of years. Alternatively it is utilized in some other absorptive process such as horticulture or the production of plastics or chemicals. There are myriad risks to carbon storage, including the potential for seismic events and carbon leakages on land and in water that may cause harm to human and marine life. It is also a very expensive process to undertake and uses a lot of energy in and of itself.
One of the technology’s most controversial applications is injecting carbon into oil fields that are not otherwise recoverable, a process known as Enhanced Oil Recovery (EOR). The irony of relying on carbon emissions to propagate fossil fuel extraction is not lost on CCS detractors. Nevertheless, CCS projects have continued to grow and as of 2021 there were 27 large-scale CCS projects operational across the globe, with another 108 in the pipeline. The potential of CCS to slash emissions from carbon’s big industrial hitters like cement and steel look extremely promising.
Carbon Capture And Storage In Waste-To-Energy Plants
So can CCS become a viable solution for carbon emissions from WTE plants and what are the specific concerns to that industry? Capturing the carbon from waste incineration is a relatively new idea, whereas we’ve been capturing carbon from traditional power generation for years, as well as from manufacturing plants for materials like iron and steel, hydrogen production, and fertilizer production.
On the one hand, its viability seems to depend on to what extent we reduce the amount of MSW we produce. Or, to put it another way, how close to the stated desire of a circular economy can the Environmental Protection Agency (EPA) and Biden administration get. By definition a circular economy means cutting the inputs for the WTE industry – incineration is obviously a linear process by nature. This issue is becoming even more stark in Europe, where the EU’s Circular Economy Action Plan aims to halve residual waste by 2030 (from 2018 levels) and cut it out altogether by 2050. Of particular concern to the WTE industry on both sides of the Atlantic must be the push to cut out single use plastics which have a combustion gradient nearly as high as fossil fuels, making them particularly valuable to the WTE process. In Copenhagen, they are having to import waste in order to stoke their furnaces, and in Italy they are stopping building new WTE plants as the waste stream reduces there.
And yet the WTE industry argues that around half of all MSW won’t ever be recyclable and so must inevitably be sent to landfill or WTE plants – the latter being objectively preferable. This argument gathers steam when we consider the big bans on exporting plastic recycling which leave the US and EU with insufficient infrastructure to recycle their own plastic. A study has shown that even with circular economy measures in place in the EU in 2035, residual waste will still outstrip the continent’s incineration capacity. The rebuttal to these positions is that in necessitating an ongoing supply of MSW we enter into a self-fulfilling prophecy; disincentivizing and ultimately preventing MSW reduction. How are government and private sectors going to parse this dichotomy?
It seems like a medium term compromise, in which both increased recycling and waste reduction are pursued alongside the proliferation of CCS, is inevitable. Afterall, what else can we do with our millions of tons of waste while we transition toward a circular economy? The challenges of such an approach are vivid. If captured carbon is being utilized to extract yet more fossil fuels it starts to feel like one step forward, two steps back. Regulators must walk the tightrope between adequately funding CCS technologies to encourage proliferation in the private sector, while ensuring that the incentives to reduce emissions from production are still present.
In the US, the Office of Fossil Energy and Carbon Management is responsible for distributing $10 billion to carbon capture and storage innovations. An important part of their function is to funnel those investments into projects that employ a broader range of metrics than merely the amount of carbon sequestered, including human health, air pollution and the impact on communities. By valuing the right metrics they seek to avoid CCS becoming simply a license to extract additional fossil fuels.
With the growth in MSW and the universal consensus on the imperative to limit the use of landfills, WTE looks set to continue its project. Ultimately, commentators say, whether carbon capture and storage takes off will depend on creating a market for the captured carbon and on whether it can be effectively and safely stored. If this can be achieved, the potential for CCS to make a truly carbon negative process out of WTE is a big win for governments hoping to meet ambitious climate targets by mid century.
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