Renewable and sustainable energy to provide dispatchable, stable power with realistic cascading energy applications
GEOTHERMAL: ENERGY BEYOND POWER
Cascade Energy Applications
A binary power plant will utilise thermal heat from well head temperature down to some 100˚C; thereafter the energy can be used in pre-heaters and a range of activities that require thermal energy, typically in the agro-industrial sector. There is growing international interest in utilising geothermal energy for direct use applications such as utilisation for district heating /hot water, balneology, diary processing, horticulture and aquaculture (Figure 1).
At Lochinvar, and in Zambia generally, identified direct applications include dairy, horticulture and aquaculture, with associated processing and packaging facilities. Such a cluster or ‘resource park’ could be situated in the southern part of the geothermal resource area; these activities would create rural development with sustainable employment. At the end of the cascade utilisation of thermal energy the geothermal fluid will be re-injected into the reservoir.
Such direct applications of geothermal energy in the Kafue Trough could play an important role in rural energy & rural industrialisation policies, leading to food security and sustainable economically viable employment. This is particularly pertinent in the context of developing resilience to implications of climate change.
Figure 1: The cascade use of geothermal energy
Dairy product processing is a natural fit to geothermal. In New Zealand, the Maori Tuaropaki Trust run the successful Miraka Milk Plant. A recent study in Kenya with a similar objective was positive and is now being implemented by the Kenya’s Geothermal Development Corporation. Nationally, Zambia milk production is in significant deficit to demand and significant volumes are imported; actual production is well below estimated capacity; also, there is very little powdered milk production which for the HIV programmes would be desirable.
The key to a dairy processing would be the availability of product and the interest of the local community in the project. It is estimated that there are some 90,000 head of traditionally managed cattle in the Lochinvar-Monze-Namwala area. Little milk from these herds reaches the market as collection points are scarce (see Figure 2 below). Any initiative could be coupled with the control of cattle and human conflict in the part of the park, thus allowing the natural habitat to regenerate so supporting the redistribution wildlife, and so making the park important for tourism. All of this will require stakeholder cooperation.
Nteme Milk Co-operative, 10km North of Monze
(and 35km from Lochinvar), the nearest
milk collection point
The use of geothermal energy to provide controlled heating for greenhouses in being increasingly implemented globally. A good example is Kenya where significant volumes of roses and vegetables such as peppers are grown in greenhouses adjacent to and heated by the Olkaria power plants; the growing and ripening times are reduced by an average of 30%.
Fish provide an efficient source of protein which is lacking in the diets of many Zambians; the Government has made aquaculture a priority and has provided fiscal incentives. The correct temperature of fishponds can make a significant difference to the growth rate of many fish species. In a natural setting this is apparent in Zambia’s Lake Mweru which is several degrees warmer than other lakes in the region and has larger fish stocks. In tanks it has been determined that Tilapia at optimum water temperature grow from egg to ready to eat in 4 months whereas in the wild it is some 12 months. Given the over-fishing of the Kafue River and the current lack of processing until the fish reach Lusaka, there could be scope to develop both aquaculture and processing as part of a geothermal energy resource park. Waste from aquaculture can be fed back to horticulture which can be run in the form of hydroponics.
Distribution of processed agri-industry products: As noted in the ‘Locality’ paragraph above, the geothermal resource area is some 45km from Monze which itself is on the Livingstone-Lusaka trunk road as well as the railway line which links both RSA, Namibia and Botswana with Lusaka and the Copperbelt. It is understood that this route may become the regional transport corridor so reducing the reliance on the SA-Zimbabwe-Chirundu link which does not have a rail line.
Zambia’s Ministry of Commerce Trade and Industry is cooperating with the company to investigate and sensitise local communities, traditional leaders and regional government.
Other Processes for which geothermal energy and power could be used
Spas and hot baths associated with geothermal are another common application. Examples include the man-made Blue Lagoon in Iceland which has been created from the outflow of the Svartenji Geothermal power plant, and the Olkaria Spa associated with KenGen’s Olkaria power plants in Kenya. These can include restaurants, accommodation and other amenities, which make them popular tourist destinations. Such a spa could be developed at Lochinvar by the developer as part of the improvement of the Park and its amenities.
KGE is interested in determining the feasibility of using geothermal power for sustainable fuel synthesis, including production of hydrogen and other commercial gases by electrolysis. The fuel cell industry which uses hydrogen as a fuel is slowly gaining momentum globally and is a strategic priority in South Africa in conjunction with the platinum industry.
There is growing interest in the recovery of certain industrial minerals and gases from geothermal brines. Pilot recovery circuits are being operating at several geothermal power plants and gas recovery is common in Turkey. For the time being mineral recovery should be considered a retro-fit option; the need to and viability of capturing any non-condensable gases will be addressed in the feasibility study.