ZANEMVULA SUBSIDISED HOUSING SOLAR WATER HEATER PILOT PROJECT
In June 2008 the Electricity and Energy Directorate of Nelson Mandela Bay Municipality initiated a low-pressure solar water heater project in a subsidised housing area. Zanemvula was chosen as an ideal location for a pilot project of this nature. The installation of the solar water heater units began in April 2009, and to date 1000 units have been installed. The pilot was created as part of the NMBM’s Go Green Initiative, which in itself is a response to Eskom’s Power Conservation Phase, (PCP), where the aim is to reduce demand side consumption levels.
The low-pressure solar water heaters that are being used save roughly 1.8 tonnes of carbon dioxide (CO2) from being emitted each year from traditional coal power generation techniques. According to the U.S Energy Information Agency’s 1999 report 963g of CO2 is emitted for each kWh of electricity generated. This means that each solar water heater in Zanemvula saves 1869kWh of electricity per year that would otherwise be used for heating water. The amount of CO2 reduction that a project like Zanemvula achieves is one of its primary benefits, and is why this form of renewable technology is gaining ground as being viable.
The Zanemvula project has other benefits besides reducing carbon emissions. It aims at local community upliftment by providing indigent households with a source of hot water. It is hoped that this will contribute towards increasing livelihoods in a more sustainable manner. Social surveys are being conducted pre and post installation to determine the effect the solar water heaters have had in the lives of community members. Local job creation has also been improved, with locals participating in conducting the surveys, as well as some individuals being selected for training to install the systems. At the moment the NMBM is looking towards creating a maintenance team training structure that will carry out repairs to the systems for the foreseeable lifetime of the project. With proper maintenance each unit is expected to function efficiently for 15 years.
Zanemvula has been designed as a pilot project that is intended to inform future up-scaled rollouts at a National level. It is hoped that one day every RDP house is constructed with a solar water heater factored into the budget. With the proper implementation and coordination of the Zanemvula project the NMBM intends to be a part of the formation of legislation which will concretise solar water heaters into subsidised housing law. There are several other similar projects that are running in South Africa. The Kuyasa low-cost housing energy upgrade project in Khayelitsha has seen 2309 houses retrofitted with energy saving technologies. Solar water heaters are one of these interventions. The City of Johannesburg has also implemented solar water heater projects in Cosmos City where 350 households have been ‘climate proofed’ with solar water heaters, as well as ceiling insulation and rainwater harvesting measures.
Solar water heater rollouts of this kind, both small and large scale, have great potential as carbon trading projects. The Clean Development Mechanism (CDM) was formulated as part of the Kyoto Protocol in 1997. CDM essentially allows developed nations to purchase carbon credits through approved renewable energy projects in developing countries. This offsets their own emissions. One of the problems at the moment is that the process to qualify as a CDM project is expensive and lengthy, with high upfront transaction costs and a review by the CDM Executive Board needing to take place. Continual Monitoring, Measurement and Verification (MMV) also needs to take place through a Designated Operation Entity (DOE), to make sure that the CDM project is achieving its emission goals. However, there are options to sell the carbon credits on the voluntary market though Verified Emission Reductions (VER), which bypasses the need to register the project under the CDM Board, and thereby reduces the overall costs involved in running the project. Large scale (80000-10000) solar water heater rollouts are more viable in terms of CDM registration procedures. The NMBM is busy working on its carbon trading process for Zanemvula and is collaborating with other similar projects to finalise the model.
The diagram below shows how the thermo-siphon principle works in low-pressure solar water heaters like those found at Zanemvula. Incoming solar radiation strikes the collection area, which consists of several tubes that are designed to prevent energy being lost by the use of a vacuum system. The radiant energy entering the system is transferred into heat energy within the water. This temperature increase causes the volume of the water to increase, thereby reducing its density causing a net buoyancy. This causes the heated water to rise up the tubes into the tank. A siphon is created as hot water is displaced from the tubes drawing cooler water into them. The hot water connection leading into the house is connected to the top portion of the tank where warmer water is found.
The diagram below provides an explanation of how the thermo-siphon principle works in low-pressure solar water heaters
The picture below shows the typical structure of a low pressure solar water heater.
LINKS FOR FURTHER INFORMATION
Department of Mirals and Energy
Sustainable Energy Africa
Renewable Energy and Energy Efficience Partnership