The prototype must contain a sustainable energy source, increase the efficiency of the distillation process and increase the quality of the oil.
The heat source was selected to be solar energy. It was the most reliable, sustainable and powerful energy source for this region according to our rough calculations. Wind energy didn’t have the right power capacity for the heat generation and there were no dams in the area for hydropower facilities. Still, solar power is a very broad concept. Through literature studies we found an interesting article about Concentrated Solar Power[1] (CSP). The article stated “India is the world’s leading market for CSP in industrial applications”. Further research showed that CSP had huge potential for its energy capacity, because the solar power was directly converted into steam. Besides that we found that the Indian government subsidizes up to 30% of the cost of CSP systems, as part of the JNN National Solar Mission. These were promising figures.
Calculations were made on the exact amount of power needed for distillation, taking heat loss into account. These calculations can be found in the article called still calculations. For a perfect process we needed 2.96 kW and to foresee any external factors we decided an installation of 5 kW would suffice. A quotation was sent to the company Taylormade Solar Solutions PVT Ltd, which is specialized in fabrication CSP installations. The prices we received were as follows:
- Solar Steam Generating System 5 kg/hr – 210,400 Rs = €2906
- Solar Steam Generating System 10 kg/hr – 385,800 Rs = €5329
Considering the fact these costs were only for the heat source of the prototype, we concluded these prices were too high. Up scaling is no possibility with prices like these; alternatives must be sought.
During the first trip to Wayanad we were shown the solar panels that power the entire village of Valaramkunnu. There was a surplus of energy present in the PV system what creates the option to use this energy for the distillation process. Instead of manufacturing a complete CSP system, there were only a couple of solar panels that had to be added to the existing installation. However there is no direct steam production, only electricity. Therefore an extra electrical boiler had to be manufactured for the project. Another quotation was sent:
Steam Generator consisting of:
a) 15 litres capacity
b) Pressure 1 kg/cm2
c) Electrical Water Heater, capacity 1.5 kW
This was priced 49,500 Rs, which is €683,00 and shows a major difference in price compared to the CSP installation.
The main reason for the inefficiency of the process is the technique called ‘water distillation’. Here the lemongrass is put in the sill together with the water. The heat source provides the still with the energy needed to heat the water and the lemongrass, and to evaporate it. After this the steam is led through a tube that is cooled by a water tank. When it has condensed and has become liquid again it will move to the separator. There the oil will be separated and the water will be discharged. This means there is no continuous flow. From literature studies alone we were able to conclude that this method is very inefficient. The reason this technique is used is because the setup needed for this technique is easy to build, compared to setups for other techniques.
The technique the prototype is based on is called steam distillation. The main difference is that the lemongrass is not put in the tank along with the water. The steam is created in a separate cabin and then led through the lemongrass. After cooling down and separating the oil from the water the water is led through the system again, so a continuous flow is created. The exact way this is done will be explained in the article Every part of the prototype. Through literature studies we have chosen this technique as it has shown to be the most sufficient. The prototype will be used to find the perfect measurements and number for the distillation process. After reaching a potential that is high enough we can plan to build larger distillation units.
By making use of a stainless steel construction we reduce the corrosion that severely damages the quality of the oil. A proper separator will also make sure that only the purest oil will be retrieved from the prototype.
[1] Small-Scale Concentrated Solar Power: A review of current activity and potential to accelerate deployment, March 2013, James Rawlins and Michael Ashcroft, Carbon Trust