Water vs Power: Can dams solve 2 major crises?

Posted at 06/06/10 11:46 PM

MANILA, Philippines – On normal days, the Angat dam in Norzagaray, Bulacan releases an average of 50 cubic meters per second of water, initially passing through penstock and turbines to produce a maximum of 246-megawatts (MW) of electricity.

After hurdling the turbines, water takes on two separate routes: one is piped through Metro Manila’s ancient water channels and into faucets of around 15 million homes; while the other takes the lesser complicated route across farmland pipes to irrigate 31,000 hectares of rice fields in the provinces of Pampanga and Bulacan.

Since it started operation in 1967, the Angat reservoir had become the main supplier of Metro Manila’s daily water needs. The Water Code has also maximized its use to include irrigation and power generation depending on available water supplies in the reservoir.

Water from Angat dam is also source of ancillary power by the National Grid Corporation of the Philippines. If power producers fail to supply requirements in the Luzon grid, Angat is expected fill the gap.

This responsibility, though strategic in the midst of dwindling power supplies, doesn’t sit well with critics since the dam should be prioritizing household consumption needs — especially during dry spells. 
Vital role

Water from dams are mainly for domestic consumption, but during black-outs and when other power plants cannot deliver their allocated supply, hydro-electric power plants are commonly utilized to plug the shortfall.

“This is the vital role of hydro,” Gregel Redublado of the Dams Reservoirs and Flood Forecasting department of the National Power Corporation (Napocor)told abs-cbnNEWS.com.

Redublado said that water from dams is often used to block-start the whole grid system if there are sudden shortages, or in cases of an accidental total shut-down.

The reason is simple, hydro plants can produce huge energy supply in a short period of time by releasing large amounts of water that will in turn move the turbines.

Similarly, larger hydro plants can be utilized for 2 to 3 hours as start-up, giving enough time to send electricity to other power plants and stabilize the grid.

Ancillary power

The crucial role of hydro plants makes it an effective last recourse measure in balancing energy shortages.

Electricity from hydro power facilities are sold at the Wholesale Energy Spot Market (WESM), which serves as a trading ground for electricity in the Luzon grid.

At WESM, each plant has a required allocation based on the day-to-day demands of the grid. When one power plant fails to deliver the electricity, the power has to be taken from ancillary sources.

Most often, hydro plants are tasked to provide additional energy capacities because of easy start-up.

According to Redublado, NGCP recommended Angat as an ancillary source of power for 3 reasons: the water source is easy to refill through rainfall, water is cheaper than other energy sources, and Angat is at the center of the Luzon grid.

“If there are discrepancies in the system, we have to adjust the dispatch to the grid. Power has to be sourced from other plants. Angat has to provide ancillary power sometimes so we have to release more water,” said Redublado.

Drying water reserves

The release of more water for additional power would have not caused the ire of critics were it not for the El Niño phenomenon that had been drying up water reserves, and effectively creating a tug-of-war between domestic use and power generation.

With reserves going below critical levels, releasing additional water for power generation means less supply of potable and irrigation water.

In February, water concessionaires and consumer groups complained of the seemingly inconsiderate manner that Napocor has been releasing additional water for power generation.

With water levels teetering at 196.08 meters, near the critical level of 180 meters, these groups feared the situation will worsen if Angat continues to supply additional power to the Luzon grid.

The water shortage also coincided with dwindling fuel resource in the 650-megawatt Malaya thermal plant in Rizal, and the delayed entry of the newly-privatized Limay gas turbine that strained the grid.

“Given the current water levels in our dams, (the energy secretary) must ensure that water is no longer used to generate power and that government must look into other power sources instead,” the Consumer and Oil Price Watch said in a statement in February.

In Mindanao, where a spot market has yet to be established, electricity remains largely dependent on hydro sources. This dependency has triggered rotational blackouts earlier this year that last between 4 and 12 hours daily.

The biggest player in the Mindanao grid is the 7-unit 727-MW Agus Complex in Misamis Oriental and Iligan City. With additional power from the 255-MW Pulangi 4, the two plants provide 57% of the island grid’s daily power needs.

Engineer Pablita Encabo, Napocor operations superintendent in Pulangi 4, said that when water levels hit 282.15 meters, silt will enter the turbines and ruin the cooling system.

“When waters go below 282.15 meters, we don’t draw water anymore. We reduce load to lessen the entry of foreign materials. For every centimeter loss in water supply, we reduce the power load,” Encabo told abs-cbnNEWS.com.

By mid-March, power demand in the grid has reached a whopping 700-MW, but Agus and Pulangi were only producing 50-MW and 30-MW respectively, less than 10% of their usual capacities.

Unlike the Angat situation in Luzon, there is no excess water that can be drawn from Mindanao reservoirs.

“The El Nino deeply affected us because we cannot supply the energy demand of the system even if we want to,” Encabo said.

Water or electricity?

In the tug-of-war between power and water, which should be prioritized?

The Presidential Decree 1607 or the Water Code, spelled it out: the priority should be household and irrigation use rather than power generation.

“Water is a basic need and it has to be always prioritized than electricity," said Redublado.

For water concessionaires Manila Water and Maynilad, the shortage could have been prevented if there was more careful and deliberate power planning.