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

PUBLISHED : Thursday, 04 February, 2016, 5:47pm
UPDATED : Thursday, 04 February, 2016, 5:52pm

We must give credit to Elon Musk for bringing up the issue of solar energy in Hong Kong. We should have a solar policy; when so many people here use sunscreens all year round, common sense tells us that there must be plenty of solar energy to harness.

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.

Yet, we are not using renewable energy from the sun wisely. The sun heats up the roof and we burn fossil fuels to power air conditioners to cool the room below. Even though the efficiency of converting solar energy into electricity is about 10 per cent, in practice, solar panels atop a village house could generate 840kWh of energy a month, worth some HK$1,000.

A village house rooftop solar system could fully charge an electric vehicle every 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.

City Hall car park offers another opportunity for installing rooftop systems. Car owners do not want to park on the top floor in summer because of how hot their cars can get. If we put raised solar panels on the top floor, we could harvest the solar energy for charging electric vehicles and reduce the heating of cars parked below the panels. Parking revenue would also increase.

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.

Japan, meanwhile, is building a solar farm on water, covering the Yamakura Dam reservoir (around 18 hectares) with 50,000 solar panels, generating 13.7MW of power when complete. Singapore is considering doing the same. We have two huge reservoirs which could house large floating solar farms. If we look hard enough, we can always find places for solar installations.

Reservoirs are run by the Water Supplies Department, which has little or no incentive to harness the sun’s energy

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.

A solar energy project would bring new hope and opportunities. It would provide a stimulus to creating high value-added green industries (solar energy, energy storage and management, green transport), providing new jobs for our youth and making full use of our underutilised land. Electric vehicles would reduce air pollution. Turning a neighbouring landfill into a green energy park would bring pride back to a community, and eventually higher property values.

READ MORE: China can ‘easily’ support all its energy demand using homegrown solar power, says Tesla’s Musk in Hong Kong

So, how can we make this happen? The existing scheme of control agreement between the utility companies and the government will expire in 2018 and is under review. It provides a 9.99 per cent permitted rate of return on average net fixed assets other than for renewable energy fixed assets, for which the permitted return is 11 per cent. Thus, if the utility companies were to invest in renewable energy, they would be able to set higher tariffs. Instead, the government should consider allowing third-party renewable electricity generators to supply to the grid.

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.

Solar farms, combined with the latest battery storage systems, are becoming very popular for such “demand shift” applications. The cost of battery storage is decreasing rapidly, and will become very affordable shortly. Metering and power purchase agreements between independent renewable energy generators and the utilities could encourage more solar power investments, reducing peak demand and therefore the need for new 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