Technology fact sheet
31 Oct 2014
- Small scale distillation unit suitable for remote areas
- Essential oils as high value product with export potential
- Technology to be operated by communities and cooperatives
- The small-scale essential oil distillation unit (DU) is designed to distil essential oils from aromatic plants found in remote areas in Nepal.
- It can be disassembled and carried to areas where vehicles cannot reach, especially in mountainous regions.
- Essential oils may be extracted from any medicinal and aromatic plant. Popular species in Nepal include wintergreen, mint, chamomile, citronella, eucalyptus and lemongrass. Wintergreen grows naturally and is collected from the wild while the other species are cultivated.
- Although aromatic plants have been collected for centuries, distillation units are relatively new to Nepal. The medicinal and aromatic plants (MAPs) sector has a considerable export potential that could enable the country to diversify exports (Jenisch and Probst, 2011). Therefore, the sector has received increased national and international attention in recent years.
Where it works
- In Nepal, DUs can be installed in the plains or mountains. Smaller and portable DUs which can be disassembled are more suitable for mountainous regions remote from roads. In the plains or mountainous areas accessible by road, larger DUs can be installed.
- The soil and water requirements depend on the plant. A supply of clean water is necessary for the technology. Access to markets is critical. The bulk of essential oils produced in Nepal are exported because of the high prices these fetch in international markets.
- Community ownership and operation of the distillation unit is recommended because of the high initial costs. Nepal has many community forest user groups (CFUGs) and any member of such a group may contribute plant material and earn money for it. In Nepal, more than half of aromatic plant harvesters/cultivators are women who can, thus, be empowered through the technology.
- Education is a critical step in adopting the technology and this is usually done through workshops, hands-on training and information dissemination during community meetings.
- Adopters should be trained in growing high quality aromatic plant species as well as the sustainable harvesting of wild species and marketing.
- The DU has a capacity of between 1,500 and 2,000 litres which can hold between 200 and 500 kg of raw plant material. It uses steam distillation to extract essential oil from raw plant material.
- The DU consists of distillation tank, a condenser, a receiver, and heat source (Figure 1). Raw plant material is loaded along with about 300-500 l of water in the distillation tank (Figure 2 and 4), which is then sealed tightly and heated directly by fire. The water turns to steam, which passes over the plant material under pressure and extracts the volatile compounds.
- The steam and volatile compounds then pass through the condenser (Figures 1 and 2), comprised of a steel coil, where these are cooled to a liquid state and exit through the receiver (Figure 3).
- At this stage, the liquid contains hydrosol (primarily water with a small amount of essential oil) and the essential oil which can be easily separated due to differences in density (Douglas, Heyes, and Smallfield, 2005).
- The oil is filtered and stored in an aluminum or stainless steel container (Figure 3). The hydrosol is recycled by adding it to the next batch of plant material in the distillation unit.
On average, it takes 4 to 8 hours to process one batch of plant material. This includes approximately 20 to 30 minutes to load the tank with raw material, 1.5 hours for the water to boil, and 3-6 hours of processing. The processing time depends on the type of plant; chamomile takes up to 8 hours, but most other plants need 4 hours. With regular maintenance, the DU can be operated for at least 10 years (Johnson, 2013).
- Between 45 and 300 production cycles are possible per year. This depends on the type of raw plant material. If only chamomile is used, there will be about 45 production cycles in a year; if a combination of chamomile, lemon grass, and mint is used, about 300 production cycles can be processed annually. Table 1 lists the most popular plants and the time of year during which these are processed.