Sustainable off-grid electricity supply using a LTE communication model for rural towns in South Africa

Abstract

As far back as 2008 the demand for electricity in South Africa (SA) has exceeded the supply of electricity (Joffe, 2012). Electricity generation in SA is a monopolistic industry driven by Eskom with most of its electricity generated by large coal-fired plants and one nuclear plant. This is in line with most countries where electricity is generated by these large power-generating plants and then transmitted via high voltage transmission systems. This situation in SA however came to a head during 2008 with a power crisis which the majority of South Africans will not easily forget. This crisis shook the South African nation and at the same time made the consumers realise that they can no longer rely on Eskom as a sole supplier of electricity and that they, the consumer will have to invest in ways to alleviate this crisis. The months of blackouts reminded every consumer how important it is to have access to electricity. Since 2008, the electricity provision in SA has seen some changes but in spite of these changes SA’s power system remains under huge strain and will continue to be under strain until Eskom manage to complete and add their latest two large power stations, Medupi and Kusile to their network to deliver the capacity needed to relieve the shortage of supply. Recovering from the effect that the 2008 crisis had on the South African industries and the public as a whole is without doubt the most pressing and immediate challenge for South Africans. As this is to the long term prospects for the economy a secure supply of electricity is essential. This will have to be done at a cost which South Africans can afford if the economy is to sustain better and faster rates of investment and economic growth whilst providing access to electricity for all. It is therefore absolutely critical that the dependence on Eskom as a sole supplier of electricity should diminish. The South African government and policymakers will, therefore, need to consider measures on how to transform Eskom to allow its current grid to integrate alternate power generation sources such as renewable energy to open up opportunities for independent power producers (IPPs) to compete and stabilise the country’s electricity supply market. In addition to the inputs from the South African government and the policymakers South African industries and potential power generators will have to expand the energy supply mix in SA. This is important if the industry is committed to addressing the challenges of climate change. New players in the energy generation fields will have to be brought in together with new investors, technology and skills. One of the biggest challenges is to convince the South African government that an energy generation monopoly is no longer sustainable and that an energy generation mix can be perhaps more sustainable, reliable and “cleaner” if the right balance between IPPs and SA’s monopoly energy generator is carefully orchestrated and properly governed. Affordable cost structures will attract investments from IPP’s and have already started doing so. Fin24 (Lameez Omarjee (Fin24), 2019) reported that South Africa’s Energy Minister Jeff Radebe explained; “The National Energy Regulator of SA (Nersa) issues a licence to all IPPs, based on a full disclosure of information required, tariff and tariff escalation. A public participation process also takes pace to scrutinise the tariff before a licence is granted, before Eskom signs purchase power agreements (PPAs), Nersa will issue an approval for Eskom to enter into PPAs and confirm in writing that Eskom will be allowed the full associated cost under the cost recovery mechanism. Radebe further stated that the cost of buying energy from IPPs through purchase power agreements (PPAs) was included as expenditure, before the calculation of Eskom's operating profit” (Appendix A provides more insight). With the many renewable energy resources being developed, distributed power generation is an alternative way of diversifying the energy mix to satisfy most of the above requirements. The challenge here is how South Africans ensure that distributed power generation as an integrated energy mix between existing generation and new renewable energy generating resources are optimally utilised. In light of the growing global population which is driving an even greater increase in the demand for electricity and governments around the world focusing on reducing carbon dioxide (CO2) emissions by increasing the utilization of renewable energy sources in the power, chain seems to be the ultimate answer. In addition, these complex challenges are indeed driving the evolution of smart grid (SG) technologies which come with a whole host of new challenges and questions that needs to be answered. One of the most important challenges and questions to be answered is how effective communication systems will be deployed within smart grids (SGs) that will have highly efficient, fast very reliable and very secure characteristics to transmit and respond to any type of fault conditions which may occur within SG’s. There are many wireless technologies available such as Cognitive Radio Networks (CRNs), 3rd Generation Partnership Project (3GPP) release, Universal Mobile Telecommunications System (UMTS) and Long-Term Evolution (LTE) etc. Cognitive radios are intelligent software-defined radios (SDRs) that efficiently utilize the unused regions of the frequency spectrum, to achieve higher data rates. The CRNs however is an unlicensed technology which suffers from lower Quality of Service (QoS) (Ekström, 2009) and high latency problems. LTE and 3GPP releases is a promising licensed technology which addresses issues of QoS and latency, one of the technologies which can address all these issues (Patel et al., 2016). The potential of utilising existing LTE networks could reduce the cost of operation and expansion during the introduction phase of SG deployment in SA. Some work is available in literature to ascertain the viability of LTE as a communication technology for SG applications (Peng Cheng et al., 2011). For the purpose of this thesis, different communication networks will be studied, compared and modelled to determine their suitability for deployment within SG’s for rural areas in South Africa. In this thesis, the work is done mostly on communication technologies that can automate and manage the increased degree of complexity when the present grid system will be replaced by a smart grid. The digital technology that will allow a swift communication between the user and the utility, along with sensing along the transmission lines. The research considered smart metering, different interruptions, power outage and disturbances as a type of call that might originate in smart grids. These calls are handled using cognitive radio networks first and which are replaced by LTE networks due to the problem of license in cognitive radio networks.