Geothermal Heat for Soil Sterilisation

Abstract

A study was made on using geothermal heat to sterilise soils of the Oserian flower farm located adjacent to Olkaria geothermal field in Kenya. Field experiments were conducted to evaluate different techniques of soil sterilisation. Injection of steam in to the soil proved to be the most efficient method; however it involved complex design and higher capital expenditure. A hot water spray system was adopted for its simplicity and low capital cost. Heat from an existing geothermal well, which is not suitable for electric power production, is to be supplied to a plate heat exchanger to produce clean hot water which would be sprayed on to the soil to sterilise it. Main issues such as soil characteristics and horticultural aspects, design aspects of the system including analysis of heat demand, availability of heat from the well, fluid transmission and distribution are discussed. Comments are made about construction and operation of the system.