Forum: Rethink large-scale solar installations

An artist's impression of the upcoming floating solar farm at Tengeh Reservoir. The farm is expected to offset about 32 kilotonnes of carbon emissions each year, equivalent to taking some 7,000 cars off the road. PHOTO: PUB/SEMBCORP
An artist's impression of the upcoming floating solar farm at Tengeh Reservoir. The farm is expected to offset about 32 kilotonnes of carbon emissions each year, equivalent to taking some 7,000 cars off the road. PHOTO: PUB/SEMBCORP

As work begins on one of the world's largest floating solar farms at Tengeh Reservoir, I would like to draw attention to the less well-known side effects of large-scale solar deployments (One of world's largest floating solar farms coming up in Tuas, Aug 19).

One issue is the risk of contamination to our water supply arising from the use of plastic in constructing the floating pontoons used to support the photovoltaic panels.

Although the PUB will be using food-grade high-density polyethylene to minimise the impact on water quality, research has shown that no plastic is truly safe in this regard.

High-density polyethylene is commonly used in plastic bottles, grocery bags and cereal box liners. It is considered "safe", but has been shown to leach oestrogenic chemicals dangerous to foetuses and juveniles.

At the same time, the HDB is building enough rooftop solar capacity to power about 135,000 four-room flats over the next 10 years.

While the intent to cut back on carbon emissions is laudable, researchers have discovered that rooftop solar installations raise local temperatures by creating a solar heat island effect similar to that of industrial areas.

This is because solar panels are usually made of dark materials that promote high solar irradiance.

Such materials absorb a relatively high amount of solar energy over a given area and emit most of it back into the environment.

The studies revealed that solar farms have the potential to raise ambient air temperatures by 3 deg C to 4 deg C.

Given our tropical climate, the energy costs of counteracting this heat island effect (via air-conditioning or other energy-intensive means) may more than offset the energy generated by solar installations.

In fact, a "greener" and cheaper solution to reducing our overall contribution to global warming (and not just our carbon footprint) may be to simply paint our roofs white.

This is called a "cool roof" initiative, and has already been adopted by the United States Department of Energy to help meet its climate targets.

Peter Heng Teck Wee

A version of this article appeared in the print edition of The Straits Times on September 22, 2020, with the headline 'Rethink large-scale solar installations'. Print Edition | Subscribe