No solution to ecological havoc in Hofra z-Zghira

No solution has so far been identified for the impending ecological threat posed by the hourly flow of 43,000 cubic metres of warmer water into the Hofra z-Zghira outflow from the new power station at Delimara.

A proposal to reverse the direction of the intake and discharge of cooling water at Delimara has been shot down in a report presented by Enemalta, as the works required would disable the power station for 12 to 16 weeks.

Presently, cold water from Marsaxlokk Bay, which is used to cool the power station’s turbines, is being discharged in the environmentally sensitive Hofra z-Zghira cove.

The Malta Environment and Planning Authority’s integrated pollution prevention control (IPPC) committee had asked Enemalta to consider reversing the flow, so that the water is discharged in an area in Marsaxlokk bay where the adverse effects will be limited.

The Hofra z-Zghira cove presently receives 29,500m3 of cooling water every hour, which is 8ºC above the average water temperature in the area. With the proposed power station extension, the amount of warmer water will increase to 43,000m3 every hour.

The water from Marsaxlook is treated with a biocide agent to maintain the plant’s operational efficiency. But the new 144MW extension requires an additional 450 litres every week of sulphuric acid and 450 litres per week of Biocaf (a brand of biocide), which will ultimately end into the sea.

The discharge from this increased flow of warm water and biocides is expected to have a negative impact on sea grasses and corals.

Increased sea temperature is expected to result in reduced oxygen in the water, which could affect fish physiology, including spawning, egg hatching and development, feeding, digestion and growth.

No solution in sight

The latest report by engineer Anthony Bartolo from consultants AIS says that reversing the flow back from the Hofra z-Zghira outflow to Marsaxlook would entail repositioning of pumps, screens, filtering devices and their associated foundations and other civil works.

But the works would take up to 16 weeks to implement and Delimara power station would even have to be shut down during this period. And in the absence of an alternative power supply such an option cannot be even considered.

The report also claims there isn’t enough space to fit the cooling water pumps at Hofra z-Zghira.

An earlier report last March had also discarded three other options to solve this problem.

One solution used abroad is to dispose the water into an artificial cooling pond.

But this was excluded because a power plant like Delimara would require a pond with a cooling surface of around 3.6 square kilometres – that’s around 75% of Marsaxlokk, including the Delimara Peninsula.

Another solution is to build a cooling tower that reduces the water’s temperature to ambient water temperature before discharge. But to cater for the flow, the draft tower would have a 900m² footprint and be almost 30 metres high, taking up valuable space in Delimara. 

The other option would be an outfall pipeline way out into the sea, but this in itself would cause a disturbance to the marine environment.

The best solution, according to the March report, was to combine a smaller cooling tower with a shorter extended outfall and a reduced water flow.

But the latest report shoots down this proposal, because the outfall extension must be anything between 100 to 500 metres long to achieve any significant reduction in cooling tower size.

“A cooling tower, even if used in conjunction with a greatly extended outfall pipeline, would necessitate a very large footprint and this is not available at the Delimara site,” the report states.

The report also says a cooling tower would consume energy from the plant and increase its carbon footprint, apart from putting employees at risk of contracting Legionnaire’s Disease from droplets emerging from the cooling tower.