Although many kinds of projects can avoid emissions or enhance removals, some types of projects have a harder time meeting essential quality criteria than others. Industrial gas destruction projects typically have clear additionality, for example: as long as they are not required by law, there are few if any reasons to undertake them aside from generating carbon credits.[1] For many renewable energy projects, on the other hand, careful scrutiny is required to determine whether the prospect of carbon credit sales played a decisive role in their implementation (and even with such scrutiny, it can be hard to be certain – as they are often on the margin of viability with energy sales revenue alone).
Perhaps the easiest way to reduce the risk of buying lower-quality carbon credits is to restrict purchases to credits that come from lower-risk project types. The table below provides an overview of the relative quality risks associated with common types of carbon crediting projects.
There are two potential drawbacks to this approach. First, as the table below indicates, there are only a handful of project types that have low environmental integrity risks as a class. Second, the kinds of projects that can most easily meet environmental integrity requirements tend to be projects that offer the least in terms of environmental and social co-benefits – and vice versa. Often, a buyer must choose between a project type with lower quality risks and one with greater co-benefits. A project that avoids N2O emissions at a nitric acid plant, for example, will generally be highly additional, easy to quantify, will pose no ownership or permanence concerns, and will not cause social or environmental harms – but it will do little to enhance people’s livelihoods or otherwise improve the environment. An agroforestry project that sequesters carbon in trees across many small farms, on the other hand, may yield a multitude of local benefits – but its GHG impact will be harder to quantify, and the carbon stored in trees may not be permanent. These kinds of trade-offs can be observed in the tables that specify Lower-, Medium-, and Higher-Risk Project types that are linked below, which also identify the project types that offer the greatest potential for social and environmental co-benefits.
Pros: Sticking to project types that have a lower risk for quality deficits (e.g., because they typically are additional, are easier to quantify, and do not pose permanence, double counting, or social and environmental harm concerns) can be a relatively easy way to avoid low-quality carbon credits.
Cons: Lower risk is not the same thing as a guarantee of quality. The standards and methodologies used to certify projects may still be important. Furthermore, limiting purchases to lower risk project categories may exclude many valuable mitigation activities, including those with social and environmental co-benefits.
Overview of Lower, Medium, and Higher Risk tables presenting relative credit quality risk for different project types:
| Lower-Risk Project Types | Medium-Risk Project Types | Higher-Risk Project Types |
| - CO2 usage | - Methane capture and utilization | - Agriculture |
| - Methane destruction (w/o utilization) | - Methane avoidance | - Biomass energy |
| - N2O avoidance from nitric acid production | - Energy distribution | - Energy efficiency, industrial demand side |
| - N2O, adipic acid | - Energy efficiency, household demand side | - Energy efficiency, supply side |
| - Ozone-depleting substance (ODS) destruction | - PFCs & SF6 avoidance/reuse | - Forestry & land use |
| - Direct air carbon capture and storage | - Renewable energy, small scale | - Fossil fuel switching |
| - Enhanced weathering | - Fugitive gas capture or avoidance | |
| - Low-carbon transportation measures | ||
| - Renewable energy, large scale |
Related pages:
Lower-Risk Project Types
Medium-Risk Project Types
Higher-Risk Project Types
[1] While additionality is not usually a concern, it may be in some cases (e.g., where most industry players, or a particular actor, have already agreed to voluntarily mitigate emissions). Furthermore, some kinds of industrial gas projects have issues with baseline estimation and overestimation of avoided emissions.