Creating two separate time zones in the country could lead to a massive annual saving of about 500MW of electricity generation, says an internal Eskom study.
Eskom’s figures show that it currently costs R10-million per megawatt to build new power capacity, suggesting that energy savings from more efficient use of time zones could obviate the need for R5-billion in new capacity.
Electricity supply in recent times has been subject to outages as Eskom runs out of spare capacity. The utility has warned that supply interruptions can be expected until two new giant, coal-fired power stations come on stream in 2010.
A study by Eskom Generation’s Deon Joubert found that splitting the country into two times zones, with Gauteng, KwaZulu-Natal and Mpumalanga in the east and the others in the west, meant that the hourly increase in load, from the hour just before peak to the peak hour, is about 1 400MW in the winter and 1 300MW in summer.
”Peak load is sustained for one hour only. The assumption is therefore that, if 40% of the hourly increase could be delayed by one hour, the peak would be lower by 40% of 1 400MW, therefore lower by 560MW,” said Joubert.
Eskom’s capacity currently stands at 36 400MW. It operates with a reserve margin of between 8% and 10% against an accepted global norm of 15%. Joubert has stressed that his study, based on 2000 data, is preliminary, but worthwhile of further investigation.
”The study focused on the benefit to the electricity industry alone, and did not consider the social benefits (for example, having the nice late sunsets or more usable daylight hours in Gauteng, as they have in Cape Town).
”There would obviously be some logistical implications, for example, radio and television broadcasts and airline schedules, but in other countries such as Australia, Canada and the United States, where there are not just two, but five or six time zones, they cope without any problem, so why should we not? I think that the airlines would benefit too, by spreading the load over a longer period and thus utilising their aircraft better.”
Joubert said a possible 560MW saving from two time zones is more than Palmiet Pumped Storage Station’s total capacity of 400MW.
”If the assumptions are correct, two time zones would enable Eskom to delete one Palmiet-size pumped storage power station permanently from the future capacity plan.
”Also, if a greater-than-one-hour difference is assumed between the two time zones, the reduction in peak load would be greater (a two-hour difference more than doubles the reduction and one and a half hours will be somewhere in between).”
One issue identified by Joubert is whether Limpopo should fall within the eastern or western time zone.
Time zone adjustments, either on a seasonal or annual basis, have a potential benefit for South Africans who live in the eastern part of the country. In Durban and Johannesburg, for instance, sunset could be at about 8pm at present rather than 7pm.
The potential savings from implementing two time zones appear significant compared to the total 4 000MW that Eskom intends saving from demand side management (DSM) programmes between now and 2020.
Eskom general manager: investment strategy, Andrew Etzinger, said he was not aware that Joubert had written a report (on time zones and energy saving). ”I will need to obtain a copy thereof before expressing an opinion.”
He declined to comment on whether Eskom had considered using daylight saving as part of a wider DSM strategy.
There is also growing support to implement daylight savings time (DST), where clocks are adjusted seasonally, in South Africa.
Online encyclopaedia Wikipedia lists numerous benefits from daylight savings time, including lower energy use through more efficient use of daylight, reduced crime and road accidents.
Budget air carrier kulula.com, which has been campaigning for daylight savings, this week made an urgent appeal to government to consider introducing daylight savings time on the grounds that significant power savings can be made.
It says it has collected tens of thousands of signatures and has the support of many large corporations.
‘Being in the leisure and travel industry, we will no doubt benefit from daylight saving time, but we really believe that the entire country will benefit from an extra hour of light,” said kulula.com’s Gidon Novick.
Studies done by the US’s department of tansportation have shown that DST in that country has trimmed power usage by 1%, said kulula.com.
DST ”makes” the sun set one hour later and therefore reduces the period between sunset and bedtime by one hour. This means that less electricity would be used for lighting and use of appliances late in the day. The studies also showed that most people plan outdoor activities during the ”longer” days of spring and summer and therefore are not consuming electricity at home. DST, which is implemented by turning our clocks forward by one hour during the summer months is currently practised in 70 countries including neighbour Namibia, it said.
DST brings energy savings through lower early evening home electricity consumption, prevents crime which is more prevalent after dark, brings lifestyle improvements through more leisure and family time in the evenings, and reduces traffic accidents through more people travelling from work to home during daylight.
A briefing paper by the department of minerals and energy, in response to the Kulula campaign, said the department has been frequently approached to consider daylight saving as an energy conservation measure.
The department says that DST would have a marginal impact. It says it is very difficult to quantify the energy effects on an analytical basis and it is doubtful that these could be measured accurately.
It says summer afternoons are generally long enough for sport and recreational activities and there is currently no agreement in the US on whether or not to keep daylight savings: ”There is a petition currently against daylight savings that can be viewed at www.standardtime.com, ” it says.
Not a good idea
In pre-Boer War days all the mines on the Witwatersrand adhered to a permanent daylight saving scheme and there was a difference of one to one and a half hours between mine and town times to allow employees more time for recreation.
Longitudinally, South Africa is situated between approximately 12 degrees and 33 degrees east. South African standard time is determined by the meridian of 30 degrees east — two hours ahead of Greenwich Mean Time. As the meridian of 30 degrees East on which South Africa standard time is based is well towards the east of the country, it means that most of the country already, to a certain extent, enjoys daylight saving time. At Port Elizabeth this amounts to 18 minutes, at Kimberley 21 minutes and at Cape Town 46 minutes.
At Greenwich the earliest sunrise in midsummer occurs at 3.42am Greenwich Time, so that if the clock were to be advanced one hour and all activities were to commence an hour earlier, the clock time at sunrise would still only be 4.42am and very few people would be inconvenienced. In South Africa the situation is quite different. At Johannesburg the earliest time of sunrise is 5.28am. If all clocks were to be advanced one hour, it would mean that a great many people would have to rise in the dark and would probably have to travel to work well before sunrise.
The seasonal variation in the number of daylight hours is not significant in South Africa — ranging from 25 minutes in Musina to 29 minutes in Cape Town in midsummer.
In order to determine the impact of daylight saving on energy consumption, it is necessary to investigate the time effects of energy consumption in the various consuming sectors. Daylight saving would require each household an average of one hour less electricity a day for illumination. However, citizens living in the western areas, such as Western Cape, would have to rise and travel to work in darkness for a longer period in the year — the result being that more energy would have to be used for illumination.
If two time zones were to be considered in South Africa as a developing country, it would create much confusion and lead to scheduling difficulties.
A potential negative effect experienced in European countries is that longer daylight in the evening may lead to an extension of the so-called active time in the evening. The potential saving is therefore nullified if each private motor vehicle drives an additional 140km per year because of the gained active time. — Department of Minerals and Energy