Bright future: How Hong Kong can harness the potential of solar energy
Sunny Cheng and William Chung say solar energy’s time has come, and there are many ways it could work to the benefit of Hong Kong
Hong Kong is located favourably in the subtropics, with an annual mean daily solar power of about 4 kilowatt-hours per square metre per day, even after accounting for overcast days during the rainy seasons. For an average village house with a roof area of 70 square metres, that equates to about 280kWh of solar energy irradiation on the rooftop per day.
An electric vehicle typically needs about 25kWh of electricity to fully charge, and has a range of at least 120km. So, a village house rooftop solar system could fully charge an electric vehicle every day, eliminating the need for petrol, and reducing our carbon footprint. Considering that most city cars only cover about 30km a day, a full charge could last four days, or one village house rooftop solar system could meet the demands of three or four electric vehicles per day.
Land is scarce in Hong Kong, but there are plenty of “underutilised” areas. Converting closed landfills into solar farms is becoming increasingly popular around the world. We still have three big operating landfills and, although the prevalent practice here has been to restore landfills to grass and woodland, or sports facilities, two of our landfills are too far away to make them ideal for sports facilities. The total area of the three landfills is about 260 hectares, equivalent to 20 Kowloon Parks, of which most of the restored land is slopes, and thus not suitable for sports facilities. Instead, we should convert this underutilised land into solar farms. The slopes could house over 200 megawatts of solar panels, enough to power 10,000 electric vehicles.
Yet, even if we have a solar policy, we are still stuck. All our closed landfills are not intended for solar installations, and to do so would require the district council to change the use of these sites. The reservoirs are run by the Water Supplies Department, which has little or no incentive to harness the sun’s energy. Village houses belong to individual owners, but the Buildings Department forbids installations on the rooftops of all buildings. The Electrical & Mechanical Services Department carried out a study on the potential application of renewable energy from 2000-2004, but little was done because it is not a policy bureau. Our government and the people are locked in by existing rules and regulations.
One needs a “can-do” spirit to make things happen. We need Elon Musk’s attitude to make the impossible possible. Solar energy is becoming more affordable. Nobody expected Tesla to sell so well in Hong Kong, not even Musk.
READ MORE: China can ‘easily’ support all its energy demand using homegrown solar power, says Tesla’s Musk in Hong Kong
A power plant performs best when loading is constant throughout the day. But there are peaks and troughs every day, as well as seasonal changes. In the troughs, the turbine is generating more electricity than needed; at peak times, it struggles to meet demand. Small turbines are used to supply additional power to meet the surges. Under the existing scheme of control, investing in new turbines to meet demand surges is a gift to the utility companies. But in fact, surplus energy in the troughs can be stored and discharged during peak periods, reducing the need for booster turbines.
It is true that the previous administration did little in its eight years, passing on many problems to the current administration. But, in the past three years, the Environment Bureau has been underperforming. Let’s be clear: it is the bureau’s job to drive renewable energy initiatives, and it should break down departmental barriers to make things happen. Let’s not waste two years writing policy papers, an additional two years on consultations, three years to collect proposals, and another three to get something done.
Dr Sunny Cheng is an environmental consultant and Dr William Chung is an associate professor at the City University of Hong Kong