There has been much discussion in Finland regarding the decision by Helen, a major energy company based in Helsinki, to import cashew nut shells from the Ivory Coast to supplement its fuel portfolio for the upcoming heating season.
Maiju Westergren, Helen’s Director of Sustainability and Corporate Relations, explains in her article that the energy density of cashew nut shells is about twice that of wood chips, making them a viable fuel option even over longer transport distances. The biogenic CO2 emissions from cashew shells are lower than those from wood chips and pellets.
Although the transport distance from the Ivory Coast to Finland is long, according to Westergren, transport accounts for only about 6% of total CO2 emissions. Cashew shells meet the sustainability criteria for biomass set by the EU Renewable Energy Directive, as well as the criteria for greenhouse gas emission reductions, which is also a prerequisite for Helen to utilize them.
Based on these criteria, Westergren says that, in terms of total emissions, cashew nut shells have the lowest emissions of all the biomass fuels used by Helen, taking transportation into account.
According to Westergren, an independent third-party audit covering the entire production chain has been conducted for cashew nut shell suppliers. “Suppliers are required to comply with Helen’s supplier requirements and commit to the principles of responsible business,” Westergren writes.
The shells are a significant by-product of food production that cannot be utilized locally to any significant extent. The main uses for the shells are energy production or the extraction of CNSL (Cashew Nut Shell Liquid) as an industrial raw material.
The toxicity of the shells has been highlighted in the media. Like many industrial raw materials, cashew nut shells are not suitable for human consumption and can, for example, cause irritation upon skin contact. According to Westergren, work instructions have been created for personnel handling the shells to ensure their safe handling.
When used as fuel, cashew nut shells do not differ significantly in chemical composition from other biomass fractions used by Helen. Burning the shells therefore does not increase emissions affecting air quality at the plants.
“Helen’s plants use efficient flue gas cleaning systems that significantly reduce particulate emissions in all combustion processes,” Westergren notes.
Every day, Finnish ports safely handle tons of materials that, without proper processing, could pose a risk to people or the environment. Based on the same principle, handling processes have also been developed for cashew nut shells, and by following these, they can be safely handled and utilized for heating.
Cashew nut shells are relatively easy to handle compared to many other fuels or chemicals. Their oil is not water-soluble, which in itself prevents substances from leaching into, for example, waterways.
“According to a study we commissioned from the Finnish Institute of Occupational Health, the scent of cashew nut shells also poses virtually no risk of an allergic reaction for people with nut allergies,” says Westergren.
Westergren explains that the shells are also treated before loading to prevent any insects or pests, and furthermore, due to their structure, they are not suitable as a habitat for insects, so they do not attract other species either. In other EU and Nordic countries where cashew nut shells are utilized in a similar manner, there have been no reports of invasive species arriving via the shells.