Kenya makes all the global geothermal headlines when it comes to electricity development, and it’s no secret Kenya is quickly rising to the top as a geothermal leader based on activity and megawatts developed. But there is more to Kenya’s geothermal story than just electricity.
Direct use of geothermal energy has continuously grown in popularity due to economic, environmental and energy efficiency benefits associated with it. Applications vary widely from agricultural, crop drying, heating, and industrial processes.
Oserian Development Company Limited, a privately owned farm located in Naivasha next to the Olkaria Geothermal project has been utilizing geothermal energy for direct use applications since 2003. The use of geothermal energy has resulted in reduced operational costs, increased productivity, and significant market share due to the use of environmentally and eco-friendly practices.
In 2015, the Geothermal Development Company (GDC) set up four direct use pilot projects including a milk pasteurizer, a heated greenhouse, heated aquaculture ponds, and a laundry unit.
A low output-cyclic exploration well drilled by KenGen was initially believed to be non-productive. The well, drilled to a depth of 1617m, encountered a maximum temperature of 278°C with a steam flow rate of 14.7 tonnes per hour and an enthalpy of 1475 kJ/kg. Oserian Development Company, however, leased the well for use in greenhouse heating. Through a system of loops, hot geothermal fluid heats fresh water which is used as a heat transport medium to the greenhouse. Greenhouse heating assists in controlling relative humidity within the greenhouse especially the early morning hours when humidity tends to rise to 100%. Reducing relative humidity to below 85% eliminates fungal infection and the use of chemical fungicides. Heated water is also used to sterilize the fertilized water-reducing fertilizer waste and costs. Carbon dioxide from the well is piped to the greenhouses in order to enhance photosynthesis.
Image 1: Oserian greenhouse heating using geothermal energy (Courtesy GAK Visit 2019)
A low pressure, low-temperature geothermal well that produces a mixture of steam and hot brine is used as the source of energy. A water bath was constructed with a stainless steel heat exchanger to heat cold water from about 25°C to 85°C in a counter flow movement. This hot water can then be used in other parts of the project.
Image 2: Water bath heat exchanger. (Courtesy GDC)
A milk processing demonstration unit with a 150-liter capacity to pasteurize milk has been installed. It takes about four hours to pasteurize one batch; hence this plant can effectively be used to pasteurize bigger quantities of milk if the raw milk is available. Since this plant is located in an agriculturally rich environment, it can be utilized for milk processing for a majority of the dairy farmers in the region. Geothermal Development Company is currently seeking the possibility of procuring milk from the local dairy cooperatives to ensure continuous processing of milk using this geothermally heated pasteurizer.
Cascading has been demonstrated by re-directing the water already used for milk pasteurization and from the geothermally heated dryer to the fish ponds. Water exits at around 650C and is therefore re-usable in the fish ponds since they require temperatures of about 290C.
Image 3: The milk processing unit. (Courtesy GDC)
Geothermal heated water flows into two demonstration units of aquatic ponds to maintain a pond temperature of 29°C in a flow-through water system. These ponds are housed in tunnels to keep predators away and to also conserve heat lost through evaporation. A single, small regenerative blower is used to aerate the ponds by pushing compressed air through diffuser tubing placed along the bottom of each fish pond. This temperature is optimal for the metabolism of the tilapia species of fish, leading to enhanced growth. Fish are fed using high-quality fish food containing 36% crude protein by hand twice per day.
The first batch of fish was harvested with an improved maturity period of six and a half months on average compared to the conventional eight-month maturity age for the tilapia species of fish.
Image 4: Geothermal heated Aquatic Ponds (GDC)
Over the years, greenhouse heating has been the most common use of geothermal energy in agriculture around the world with the Oserian 50 hectare flower farm in Naivasha leading in Kenya and in the world. According to Mangi, 2013, the use of geothermal energy has proven the following benefits:
In Menengai, two crops; tomatoes and capsicum have been grown on media in the greenhouse. Wastewater from the fish ponds is filtered, additional nutrients added in fertigation tanks and fed to the crops through drip irrigation. During the night, early morning and wet seasons, geothermal heated water at a temperature range of 50°C – 55°C is circulated in galvanized pipes to raise the temperature and lower the relative humidity inside the greenhouse. Temperatures are maintained at 28°C -30°C and relative humidity less than 85%. This in return ensures less fungal infections and consequently realization of bigger produce with less use of agricultural chemicals.
Image 5: Geothermal heated tomato Greenhouse (GDC).
A geothermal heated laundry demonstration unit that consists of a washing machine and a dryer has been installed. Geothermal heated water is directed to the washers and mixed with cold water to temperatures dependent on the type of clothes to be washed, while the dryer has a specially designed fan coil unit that uses hot water to dry the clothes.
Image 6: Geothermal Heated Laundromat (GDC)
Eburru, the local community uses geothermal heat to dry pyrethrum. With proper harnessing of the geothermal steam, the local community can greatly benefit from the drying of other plants like tobacco and maize. The photo below shows pyrethrum drying by using geothermal steam at Eburru.
Image 7: Geothermal energy being used by the local community at Eburru for pyrethrum drying
In water deficit areas where we have occurrences of fumaroles and hot grounds, some communities harvest water from geothermal steam. This water is used for irrigation, watering of animals and for domestic use like drinking water, washing clothes, cleaning of floors and general cleanliness. If the chemistry of the water from the steam is suitable and within the range of drinking water and cooking, the local community within the geothermal areas, e.g., at Eburru and Suswa harvests this water and puts it to various uses.
Image 8: Water harvesting by local a community at Suswa (Courtesy)
The Geothermal Health Spa and Demonstration Centre consists of four interconnected “blue lagoons”, located on the west of Olkaria II power plant. The center acts as a tourist attraction as more tourists and visitors do patronize the Centre and Hell’s Gate National Park. The Geothermal Spa and Demonstration Centre branded Hell’s Gate National Park as the first national park in Africa where hot bathing for balneological effects is be obtained.
Image 9: The Geothermal SPA (Courtesy GAK 2019)
This concludes our special #GeothermalFactsandStats Blog post on Geothermal in Kenya, Beyond Electricity. Browse through the rest of our blog for more posts like these. It’s our goal is to educate as many as possible through these insightful blog posts on all things geothermal! Please share.
A special thank you to a Geo Energy Marketing first time guest blogger, Jesse Nyokabi
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