Hydropower at L’Ormarins
The climb to the top of the mountain behind L’Ormarins Wine Estate in Franschhoek is strenuous. You’re gaining over 300m in altitude in a distance of 1.2km, which makes the gradient rather steep, but this is what provides the 300m head which powers the 2.3MW of hydropower generating capacity installed at the behest of estate owner, Johann Rupert.
The pipe track, which delivers water to the turbines, can be clearly seen coming down the mountainside from the weir above.
If you do make the trek up the mountain, you’ll get to see the cleverly constructed weir, invisible from below, that splits the water flow out of the mountain between the pipeline that channels the water down to the turbine house, and the predetermined fixed minimum reserve flow to the beautiful waterfall that cascades down the mountain side.
Inside the turbine house it is quiet, save for a faint hum of electronics from the cabinet against the wall, which houses the control equipment for this fully automated system. The rainy season is yet to come and once it does, L’Ormarins will enjoy about eight months of green energy, which it banks for the dry season by feeding it back into the Eskom grid.
A small bank of solar PV panels on the roof of the turbine house, charges a bank of deep-cycle batteries, to provide back-up power to ensure the system remains fully automated.
The massive Ossberger turbines and their associated generators are silent, waiting patiently for the flow of water down the pipeline to hit 35 litres per second, at which point the first turbine will automatically start to spin up. After a minute or two, the generator will synchronise and connect to the grid and electricity will begin to flow.
The Ossberger turbines and their associated generators startup automatically, one after the other, when the flow rate of water from the weir high on the mountain, hits 35 litres per second.
Once the flow increases such that the first turbine reaches 90% of capacity, the second turbine will start up, and once synchronised, will begin to generate electricity as well and feed it into the grid. And all of this happens automatically, with no human intervention.
The power supply for the control equipment is backed up by a bank of deep-cycle batteries, and on the roof of the turbine house sits a series of solar PV panels for charging the back-up batteries in case Eskom power fails. The system is truly self-sufficient.
The weir on top of the mountain 300 metres above the turbine house, constructed of rock-filled gabions, ensures a constant flow of the water to the pipeline, which delivers it to the Ossberger turbine generator sets, in the turbine house far below.
“It took us 48 months from start to finish to put in this plant,” says farm manager Bob Hobson. “Aside from the two main turbines, we have a smaller one, 0.3MW in size, just down river,” he says, pointing at a mini-replica of the main turbine house, “which is started remotely by cellphone when the flow rate through the pipe exceeds 40 litres per second.”
The installation was designed and project managed by Ian de Jager, of I&F Engineering, a Cape-based company that specialises in hydropower systems. “Eskom allows farmers to ‘bank’ excess generated power. In the winter rainfall Cape, it happens during the high-demand period to June to August, when energy is double the cost it is in the summer months,” says Mr De Jager. “They can then draw power from that “bank” during the summer months.” During the June 2016 commissioning cycle of the plant, output peaked at 2.1M, which means that L’Ormarins will bank enough power during the winter months to cover its entire energy requirement for the year, plus a surplus which it will sell to Eskom.
This graph reflects the actual output of the 2 300kW hydropower plant at L’Ormarins, during the commissioning phase in June 2016. Output peaked during the third commissioning run, on June 27, at 21 000kWh. Source: I&F Engineering cc
kWh generated during the commissioning phase of the L’Ormarins hydropower plant in June 2016 (Blue - Commissioning), suggests the extent of potential output in kWh (Red - 2013 rainfall) that could have been achieved, if recorded rainfall in June 2013 in the catchment was repeated in June 2016. Source: I&F Engineering cc
“There is no way Johann Rupert would have put in this plant if the business case wasn’t solid,” says L’Ormarins managing director Gary Baumgarten. “One of the toughest tasks was getting NERSA (National Energy Regulator of South Africa) approval and negotiating a feed-in tariff,” he adds. “But we succeeded and were granted a 15-year operating license by NERSA. We’ve run interference for anybody who wants to follow our lead.”
The Western Cape is blessed with high rainfall in certain of its mountain ranges during winter, and all of this water must flow down towards rivers and dams. Elevations range from 200 to 600 metres, which makes it ideal for the development of hydropower for energy generation.
“A farmer who has any water flow – from 5 to 10 000 litres per second – from high elevation to low elevation – anywhere between 5m to 600m – can install a hydropower system. The combination of the head and flow will result in the power to be generated, depending on any loss in efficiency of the turbine and generator,” Mr De Jager says. “The cost mainly depends on the available water flow rate – which determines the size of the turbine - and the head, or pressure to be developed, which determines the type of turbine.”
“Many farmers and municipalities use valves at the end of existing pipelines to reduce pressure before releasing water into dams or rivers. This is the best place to install a turbine as most of the project is already complete. Instead of dissipating energy at the valve, the turbine can generate useable electrical energy,” says Mr De Jager.
This in in keeping with the draft sustainable hydropower generation policy, gazetted for public comment by Minister of Water and Sanitation on May 28 2016. The draft policy spells out the important role that hydropower plays in the sustainable energy mix, which is expected to deliver 6.9GW by 2030, one third of the target set in the National Development Plan. The draft policy spells out the need for simplifying licensing procedures, and it commits to engagement with independent power producers (IPPs) who wish to implement hydropower installations from pico (up to 20KW) to large (over 10MW) installations, which clears the way for farmers to capitalise on any suitable water resources they may have on their land.
Mr De Jager is currently engaged in six hydropower projects in the Western Cape with 9 730 kW generating capacity, which will generate up to 35 123MWh per annum (See figure below).
These six hydropower projects, ranging in capacity from 700kW to 3 400kW are currently in various stages of completion. The graph indicates their combined power generation capacity (9 730kW), and their potential individual and combined (35 123kWh) output, based on historical rainfall, over a 12 month period. Source: I&F Engineering cc.
“There are hundreds of possible projects ranging in size from 5 kW up to 3 400 kW,” he says, “I believe we can easily generate 20 MW on farms in the area. Hydro is normally viable from 57 c/kWh with an internal rate of return of about 20%. The average cost from Eskom is 76 c/kWh in summer and 95 c/kWh in winter, with municipalities up to double that, depending on the tariff structure.”
Anybody who wishes to visit L’Ormarins to view its hydropower installation can contact Gary Baumgarten on (021)874 9052 or email@example.com
Ian de Jager of I&F Engineering may be contacted on 082 577 0677 or firstname.lastname@example.org
The Western Cape Government and City of Cape Town launched the Energy Security Game Changer in 2015 in order to ensure that the Province has a reliable, diverse and low carbon supply of energy. This is being achieved through creating an enabling environment for the uptake of rooftop solar PV, encouraging energy efficiency and the installation of efficient water heaters, and promoting a diversity of energy sources in the province, including wind, solar, and natural gas. The Province is challenging every person in the Western Cape to contribute to an energy-secure, greener future.