Application of Renewable Energies for Storage of Horticultural Produce in Marginal Areas of Kenya: The Performance Evaluation of a Prototype Solar-Charcoal Cooler

Abstract

Kenya relies heavily on agriculture for food and employment particularly in the rural areas. It is therefore of great importance that efforts resulting in high agricultural productivity be handled with all the degree of seriousness. Due to the drastic fall in world prices of coffee and tea, there has been a steady shift to horticultural crops production such that the sector is now the second foreign exchange earner after tea. Most of the produce is marketed in many developed countries including Europe and the United States of America.

There are however, some serious challenges the sector is facing including lack of ideal facilities for proper storage of perishables and semi-perishables at the farm level in Kenya particularly between harvesting and the time when the crop is accepted by the customer. This has resulted in tremendous losses and loss of morale for the farmers. Simple and effective storage systems should therefore be developed and used to minimize losses thus improving the net returns on farmers. Refrigeration plays an important role in many countries, particularly for the preservation of food, medicine and for air conditioning. Cooling can be provided in different ways. The method adopted in industrialized countries depends heavily on grid electricity, supplied continuously and reliably to every part of the country. Less than 20% of the Kenyan population has access to electricity thus making it not only impossible but also expensive to use cold storage systems at the rural level. Alternative methods are therefore necessary.

The main objective of the research was to investigate the possibility of using renewable energies for storage of horticultural produce in marginal areas of Kenya with specific objectives mainly including the development of a prototype solar-charcoal cooler and testing its performance as related to temperature, humidity and products storageability. A prototype solar-charcoal cooler was developed at the Biomechanical and Environmental Engineering Department (BEED), College of Engineering and Technology of the Jomo Kenyatta University of Agriculture and Technology (JKUAT), Kenya and performance tested. It mainly consisted of two components:

(1)    A solar air drift which included a solar power driven fan to blow air through the charcoal to facilitate evaporation of water from the charcoal.

(2)    A cooling chamber which was lined with an aluminium sheet on the inside, charcoal layer on the outside and a water pan at the top for water supply.

The performance of the cooler indicated positive results as regards to ideal parameters affecting produce storage. These parameters mainly included variations in temperature and humidity to levels ideal to product storage. The results also indicated that various fruits and vegetables including paw paws and spinach could be stored in the cooler for longer periods as compared to when they were under ambient conditions.