**1. Introduction**

An annual average of 264 thousand tons of essential oils (HS code 3301) were exported worldwide during the period 2017–2021 [1]. The actual essential oil production figures should be higher because this annual average does not include the amounts not exported and consumed within the essential oil-producing countries. Since the essential oils are isolated from plant material with typical yields in the range of 0.5%, the yearly byproduct of the traded amounts of essential oils should have been approximately 52 million tons of vegetal material. The disposal of these large amounts of material leads to serious environmental problems associated with river pollution, incineration, or landfill overburden. Alternatively, this residual biomass

may become a valuable source of products with reduced environmental impact if a highly recommended approach, the application of the principles of circular economy, is used to add value, generate energy, and reduce waste to zero. The technological challenges are massive, but the potential benefits of following the latter principles have been the subject of many scientific articles during the past decade, not only around essential oil production but also in many different trade sectors. Waste and byproducts from food and agro-industries may no longer be associated with pollution and could be transformed and used to fight hunger and malnutrition. This chapter presents examples of the application of circular economy principles at laboratory and production scales in the essential oil agroindustry.
