Domestic Use of Energy conference focuses on DC grids

April 11th, 2014, Published in Articles: Vector


The theme of the 22nd Domestic Use of Energy (DUE) conference on 31 March – 2 April 2014 at the Cape Peninsula University of Technology (CPUT) was “Electrification for all South Africans”.

The controversial topic of DC grids formed a key focus in this discussion. The university’s vice chancellor Dr. Prins Nevhutalu opened the conference, stressing the need for more extensive electrification as a means of poverty alleviation and economic growth, as well as the need for sustainable and secure energy solutions for the future.

Keynote speakers, from left to right: Prof. Yuguang Zhou, Harry Stokman, Prof. Nico Beute, Jonathan Hodgons, and Dr. Pat Naidoo.

Keynote speakers, from left to right: Prof. Yuguang Zhou, Harry Stokman, Prof. Nico Beute, Jonathan Hodgons, and Dr. Pat Naidoo.

DC entrepreneur Harry Stokman from the Netherlands stated in his keynote address that DC grids are the future of electricity supply. His argument included traditional reasoning such as DC’s efficiency and reliability. This is also associated with savings incurred in the use of smaller electrical components (fewer raw materials are used). He says we already live in a DC world as we move to the use of renewable energy and with the standardisation in Europe on USB power supplies (which are DC) for devices which use less than 100 W. In his opinion we are moving from an AC age into a DC age.

DC grids remain a controversial issue in the electricity supply industry, with issues of safety – both at a user level relating to electric shock, and on the supply side with short circuits and fire hazards – being raised during the question and answer session. Stockman explained that DC grids can be made a lot safer than AC supplies as the currents and voltages can be measured more accurately; and that fire hazards in the supply process can be managed by leveraging other technological advances. Practicality in terms of long distance electricity supply also came up in discussion.

Jonathan Hodgons spoke about the formation of a utility for decentralised DC energy supply, and localised the DC question in a manner which addressed many of the earlier concerns. Hodgons, who works for Specialized Solar Systems, a local government contractor of solar systems in low-income communities, agreed with Stokman that DC supply will become more prevalent. His view, however, diverged from Stokman’s by focusing on energy supply in areas with no grid supply, and by looking at decentralised energy supply and micro-grids. Decentralisation is the generation of energy on the premises where the electricity is required. A DC micro-grid is an intelligent unit with efficient supply from photovoltaic cells.

According to Hodgons, we should stop solving DC problems with AC solutions. The specific problem at hand is the electrification of roughly 16 – 25% of South African homes which predominantly fall in LMS 1/4 income brackets and are not likely to be connected to the national grid in the near future. Dr. Pat Naidoo, the president of SAIEE, addressed this issue when he spoke about the engineering of micro-grids and off-grid solutions. Large low-income communities are a vital but under-appreciated asset if they are brought into the market space, he said.

Various workshops were also held at the conference. Some dealt with technical matters, such as Prof. Michel Malengret’s presentation on using Thévenin equivalents (which apply to both AC and DC grids) for measuring supply efficiency, and which can be used as a smart grid alternative which uses algorithms (which are easier to implement) rather than physical devices. Open forums led by some of the speakers dealt with new issues arising from DC implementations and micro-grids, such as billing systems and hardware matters.

Most workshops and discussions dealt predominantly with energy supply to low-income communities and the need to understand the context and issues pertaining to it. These included a presentation by Prof. Philip Lloyd on the energy profile of low-income urban communities which are crucial to dealing with the conference’s theme. Lana Franks, an electro-mechanical engineer at UCT, also delivered a case study about the informal reselling of electricity in the Imizano Yethu informal settlement, as both a form of entrepreneurship and exploitation.

Throughout the conference, it was clear that electrification of low-income communities is potentially a big market, but that it has unique complexities. It is also clear that this problem creates the space in which DC energy supply might very well and is already – making a strong comeback.

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