The figures, yet to be consolidated, come from real life readings across existing installed wind capacity, which now stands at 345MW.
If the same capital investment in wind turbines is producing much better returns than expected, then deployment should be raised well beyond the government's 8.4GW target to 2030. So argues Pascal Storck of global wind measuring firm Vaisala, whose own readings support Eskom's initial findings. Vaisala has worked on Eskom's own Kleinzee (300MW) and Aberdeen (200MW) wind farm sites as well as developer Windlab's 507MW South African pipeline.
The South African Wind Energy Association (SAWEA) is calling for consolidated wind readings to be included in a new version of the central government's 20-year energy blueprint to 2030 - called the Integrated Resource Plan (IRP) – which instructs the existing 8.4GW target. SAWEA now believes 25GW of wind capacity is feasible to 2030.
Provisionally, and pending consolidated figures, SAWEA understands real average capacity factors to be at 39.9%, against the government's initial 30% estimate. Capacity factor denotes real total plant output in the field during any given period, expressed as a percentage of the maximum possible production.
Keith Bowen, Eskom's power systems economics adviser, explains the current IRP extracted its wind data largely from modelling methods that had not been calibrated by real onsite wind measuring masts at proper heights. So, the ensuing atlas does not fully take into account the better wind resource at the greater hub heights typical of latest generation turbines. Nor does it account for high definition micrositing, whereby developers identity optimum turbine location, to the best square metre, within generally windy areas.
"Running the IRP model again will see us upscaling the industry to levels where industrialisation becomes very exciting," says SAWEA CEO Johan Van den Berg.
Wind power can deliver new capacity very quickly to allay the rolling blackouts regularly hitting the country, he adds, "and at lower cost than any other bulk source".
Eskom's new Medupi coal plant will deliver power at a cost of $90/MWh (ZAR 1,046/MWh). Eskom is drawing on costly open cycle gas generation, sometimes at around $240/MWh to help reduce outages, while wind power can deliver at $75/MWh, according to SAWEA.
But that price is average for the 2,684MW of wind either up and running (345MW) or lined up with power purchase agreements (2,339MW) through the three bidding procedures carried out under the national Renewable Energy Independent Power Producers Procurement Programme (REIPPPP). In the next bidding round, SAWEA believes the price will fall below $60/MWh.
Official IRP recognition of wind's true potential would help counter what the sector sees as a possible flagging government commitment to renewables.
Since the end of apartheid in 1994, the electricity system has hardly been extended and stands today at 44GW. Some 90% of capacity is from the country's 16 coal-fired power stations, yet the government said it intended to make private calls for around 2.5GW of coal-fired plant offers. At the same time, Eskom delays in power line build-out threaten to leave wind projects currently finalising construction without an immediate grid outlet, but Storck believes Eskom's financial woes could pull the government back from its "knee-jerk" reactions to blackout, and push it into a deeper wind commitment. Decisions made in 2015 will be crucial.