Food for thought on energy
Cooking without electricity has major benefits, writes Philip Lloyd
CHANGES in cooking energy could have a major impact on SA’s carbon emissions. A recent study, funded by the Paraffin Safety Association of SA, set out to investigate whether alternative cooking fuels could reduce the peak load and also reduce carbon dioxide (CO²) emissions.
Cooking with electricity has a significant negative impact on SA’s carbon footprint and places a massive extra load on the national electricity grid every evening. If households converted to liquid petroleum gas (LPG) or paraffin appliances instead it would reduce peak evening electricity consumption considerably and benefit the environment.
Before the recent tariff hikes electricity used to be the cheapest option for cooking meals. Now, however, LPG and paraffin are becoming more cost-effective by comparison. Cooking with LPG or paraffin also has the advantage of being very much more environmentally friendly, producing CO² emissions way below those of electricity from coal-fired plants.
It is estimated that 47% of all homes in SA cook on electricity (Census 2001), which adds more than one-sixth of SA’s generating capacity to the evening peak.
If large numbers of households moved to cooking with modern paraffin or LPGfired appliances instead it would enable Eskom to supply electricity more efficiently, as the power utility would no longer have to fire up additional peak-time power plants to cope with the demand. Little electricity can be stored for future use, so electricity production has to vary to meet the demand.
Bringing Eskom’s gas turbine plants online to cope with peak demand is costly. Cooking therefore requires much costlygenerated power and has a relatively large carbon footprint.
A study by the Energy Institute could have a major impact on SA’s carbon emission. It examined the efficiency of a number of appliances used to cook in lowincome homes, as well as the emissions of the various fuels.
It was conducted before the recent significant electricity rate hikes and showed that electricity was the preferred option for cooking on the basis of cost. However, with recent price hikes electricity has now become roughly comparable with the cost of paraffin.
Similarly, the cost of LPG is expected to halve, which will also makes its cost of use comparable to that of paraffin. Gel fuel seems likely to remain an expensive option. It is always preferable to cook using a local source of energy than to rely on distant generation.
The high efficiency of using electricity is completely offset by the low efficiency of generation and the losses in transmission and distribution.
Cooking requires heat, and providing heat by the direct combustion of fuel is far preferable to using heat to generate electricity and the electricity in turn to generate heat.
The very considerable reduction in carbon emissions of using a fuel directly in the home suggests that a programme to convert homes from electrical cooking to fuelled cooking could generate significant carbon credits.
I recommend subsidised conversion to gas or paraffin cooking, as this would be a simple way in which the demand for peak power could be trimmed.
Some idea of the benefit to be gained may be judged from the experience when electrical cookers were swapped for LP gas cookers on the Cape Flats. (Venter, L. and van der Walt, M-L. 2007. A greener shade of brown: The ability of communication to reduce demand rapidly.)
The conversion of 100 000 homes reduced the demand by 40MW. Conversion of about 5-million homes from electrical cooking could reduce the peak demand by about 2 000MW, which would have a considerable impact on the magnitude of the evening peak. To encourage conversion there need to be improvements in the efficiency of the use of paraffin-fuelled appliances, or the cost of LPG at retailers needs to fall significantly.
Philip Lloyd wishes to acknowledge Eskom Research and Innovation Division for conducting the research.