Mass balance accounting (MBA) has become a focal point in current environmental and energy policy debates, particularly as industries seek to balance consumer demand for environmentally friendly products with the realities of existing infrastructure. MBA allows producers to claim credits for using preferred inputs, such as recycled materials or lower-carbon fuels, even when those inputs are mixed with conventional sources during production and distribution.
The system works by tracking the net quantity of preferred material entering a product stream rather than following each specific molecule. This approach is especially relevant where it is impractical or cost-prohibitive to separate different types of inputs, such as biogas and natural gas in shared pipelines.
A practical example involves power plants seeking to use biogas—a methane-rich fuel derived from livestock waste—instead of traditional natural gas. While building new infrastructure exclusively for biogas would be expensive, MBA enables these facilities to utilize existing pipelines. Plant operators can pay for an equivalent amount of biogas to offset their consumption, claiming environmental benefits even though the physical gas consumed may largely be from conventional sources. “On net, the environmental effect is the same as (if not better than) if new infrastructure was built to supply the biogas, since its supply displacement effect under MBA is the same,” according to proponents.
Supporters argue that MBA reduces transaction costs associated with environmentally beneficial activities by allowing firms to use established systems instead of investing in duplicative infrastructure. This rationale underpins policies like California’s Low Carbon Fuel Standard and the Regional Greenhouse Gas Initiative, which rely on MBA frameworks.
However, controversy has emerged around MBA’s application in plastics recycling—particularly advanced or chemical recycling (AR). Critics contend that companies using AR can convert plastic into fuel while continuing to make new plastic from virgin oil but still claim recycling credits under MBA. They argue this could mislead consumers about how much recycled content is actually present in new products.
From an environmental perspective, advocates maintain that whether recycled feedstocks are used for fuel or new plastic does not change the overall reduction in oil consumption achieved through AR processes. They assert that restricting MBA would likely worsen environmental outcomes by making recycling less economically viable and potentially increasing reliance on virgin materials.
“The opposition to MBA for AR is not rooted in strong environmental economics,” one statement reads. “Rather, it boils down to opposing mechanisms that could be used to sustain industries viewed as polluting.”
Debate continues over whether selective restrictions on MBA across industries could introduce unnecessary complexity and politicization into environmental policy decisions. Proponents caution that undermining standard accounting practices could have unintended consequences for clean energy initiatives that depend on them.
Ultimately, supporters conclude that effective policy should focus directly on reducing emissions or curbing plastic consumption rather than targeting accounting mechanisms like MBA: “Policy ought to focus on effective mechanisms that directly target pollutants to be mitigated.”
