Mine debris rotting Venezuela’s hydropower plants

Mercury-laden tailings from hundreds of wildcat gold mines along the Caroni River are destroying Venezuela's vital hydroelectric assets that account for almost half of the country's generation capacity, according to five officials from the electricity ministry and state-owned utility Corpoelec.

The tailings and sediment that cascade through Corpoelec's hydropower plants on the strategic river are damaging turbines, sluicegates and surrounding concrete bases, the officials say.

The structural erosion of the assets highlights the risk of more blackouts and the massive challenge of rebuilding the crippled power grid , a key component of the political opposition's national plan for economic reconstruction.

Corpoelec maintains officially that its Caroni hydroelectric plants are not vulnerable to damage from mine tailings and related clay sedimentation. But according to an internal Corpoelec report dated March 2019, at least eight of 20 turbines at the 10GW Guri hydroelectric complex shut down indefinitely between 2013 and 2018 because sedimentation caused cracks and other damage to turbine impellers and related components.

Corpoelec on paper claims to have 34GW of generation capacity nationally including hydro, thermal and wind assets, with over 46pc concentrated on the Caroni River in Bolivar state. Since the early 2000s, Corpoelec's hydro plants supplied up to 60pc of Venezuela's national electricity demand, making up for thermal plants that were impaired by a lack of maintenance, spare parts and natural gas or diesel feedstock.

Now the hydro plants are breaking down too. Corpoelec has 52 hydro turbines with a combined capacity of 15.74GW installed at three locations on the Caroni, including the 10GW Simon Bolivar (Guri) complex with 20 turbines, 12 more downriver at the 2.6GW Caruachi complex and 20 at 3.1GW Macagua. Two-thirds of that capacity is already out of service, a Corpoelec official at Guri said.

Corpoelec reported about 7.5GW of operational generation assets nationally as of mid-June, of which 6.2GW or 83pc came from the Caroni plants, an electricity ministry official said. Prior to the first national blackout on 7 March, the river had only 10GW of operational hydro capacity, of which about 8GW was generated at Guri.

The electricity ministry has longstanding orders from President Nicolas Maduro to maximize hydro generation to compensate for the collapse of its thermal plants over the past year, including the nearly total shutdown of its 1.38GW Termozulia complex in Zulia state where only 45MW was operational as of yesterday, and the complete shutdown since first-half 2018 of the 2GW Planta Centro complex in Carabobo state near state-owned PdV's 140,000 b/d El Palito oil refinery.

Corpoelec's operational plan to boost hydro dispatch consists of accelerating water volumes flowing through its remaining operational turbines, the Corpoelec official at Guri said. The inherent danger of this strategy is that raising the velocity and volume of water flowing through the Guri, Caruachi and Macagua complexes also increases the flow of clay and tailings, further straining the turbines which have not undergone proper maintenance for more than a decade.

There is also no guarantee that pushing more water through the plants would boost electricity supply to the rest of Venezuela because critical 765kV and 400kV substations and related transmission systems are in precarious shape, the Corpoelec official at Guri said.

"The Caroni River is generating up to 6.2GW this month, but we cannot transmit all of that electricity across the country because the substations and transmission lines are not in good condition," he explained. As a result, Corpoelec is permanently rationing up to 5GW of electricity throughout Venezuela, except for Caracas which is officially exempt from the supply restrictions.

Even so, Caracas residents report dozens of daily outages since March resulting from breakdowns at substations, transformers and transmission lines.

A second internal Corpoelec report dated 24 June says Venezuela has suffered over 15,000 local electricity outages nationally since the first major blackout in early March, a catastrophic event that was quickly followed by a string of others into early April. The duration of the more recent local outages lasts from as little as an hour to up to 40 hours, particularly in western Zulia state and the Andean region.

A Corpoelec executive in Caracas acknowledged that Venezuela's electricity crisis would be "significantly worse" if not for the country's economic collapse and mass migration.

In recent years, illegal mining for gold, coltan and other minerals in Bolivar state has proliferated into a significant source of revenue for the Maduro government and criminal groups that support him, partially compensating for a steep drop in revenue from the national oil industry, which relies on the impaired grid for most of its operations.

The US and more than 50 other countries no longer recognize Maduro as Venezuela's president, but he is still supported by Russia, China, Turkey and other countries. The US-supported opposition of National Assembly president Juan Guaido is pushing for a peaceful political transition in which US financial and oil sanctions would be lifted, allowing for a reconstruction effort backed by what they hope is a type of Marshall Plan, the US economic aid package that rebuilt Western Europe after World War 2.

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