I WISH David Gleason would look more critically at renewable energy and specifically at the value that concentrated solar power (CSP) can bring to the national electricity grid.

He states in his column (Green counter-revolution grows, Torque, February 26) that "we are treading dangerous ground" by including in Eskom’s new tariff a subsidy for renewable energy providers and that this is partly to blame for the huge tariff increases being sought by Eskom.

The so-called subsidy amounts to little more than 5% of the total costs Eskom hopes to cover through its application for annual 16% tariff increases over the next five years.

What should be of greater concern is Eskom’s planned expenditure of R25.9bn to generate electricity from its own diesel-powered open-cycle gas turbine (OCGT) plants and to buy electricity from two new OCGT stations which have been commissioned by the Department of Energy from an independent power producer.

Eskom uses the OCGT plants as emergency back-up to avoid rolling blackouts during the early morning and evening peak demand periods, but the costs of doing this are huge. The two Department of Energy "peakers" will sell electricity to Eskom at R6.91 per kilowatt-hour (kWh), compared to Eskom’s average tariff of R0.61/kWh, which will rise to R1.28/kWh if its tariff increase is approved.

However, CSP plants can provide peak-period electricity at R2.51/kWh, some 60% lower than the OCGT price.

The reason CSP power stations are able to generate electricity during peak periods — when the sun is not shining — is that they can store heat accumulated during the day and use this to generate steam and electricity at night.

The first two CSP plants in SA will have up to three hours of storage, but the third will have as much as nine hours, enabling it to approximate coal-fired power stations’ round-the-clock generation capability.

More pertinently, CSP costs are likely to decline by between 40% and 28% by 2017, according to a study quoted by the Industrial Development Corporation in a recent analysis of the technology’s potential.

CSP could in fact match the price of coal-generated electricity within the next seven years.

However, despite CSP’s ability to match our country’s electricity demand curve, and at increasingly lower cost, the energy minister recently approved procurement of a further 2,415MW of OCGT and only 400MW of CSP.

This is what should be troubling Mr Gleason and the rest of SA.

Jonathan de Vries

CEO, Southern Africa Solar Thermal & Electricity Association