|Solar Hong Kong - present applications
and future prospects
Hong Kong is a high-rise and high-density city with a subtropical climate. In mid-1999, it has a population of 6.84 millions and an area of only 1,097 square kilometres. It does not have any indigenous fossil resources and depends entirely on imported fuels, including coal, natural gas and oil, for energy generation.
At present, Hong Kong does not as yet make significant use of renewable resources to meet its energy needs. Lack of incentives and shortage of land and space are the key factors limiting the deployment of renewable energy systems (Hui, Cheung and Will, 1997). Large hydropower, traditional biomass and geothermal energy are not feasible in Hong Kong because of the local conditions and resources. Only a few projects in Hong Kong now have extensively adopted some forms of renewable energy, such as solar water heating.
Nevertheless, with growing concerns about energy and the environment,
Hong Kong has been working hard in the past decade to develop energy efficiency
programmes and to find ways to minimise the environmental impact of energy
production and use (ESB, 1998). There is a need in
Hong Kong to establish a renewable energy market so as to satisfy the local
demand for green energy and create business opportunities for promoting
renewable energy in mainland China (Hui, 1997). Solar
energy systems, such as solar thermal and photovoltaics, are believed to
be one of the potential areas for future development. Under the Hong Kong's
urban context, technologies that can be integrated into a built environment
with high-rise buildings are important. Countrysides and new towns in Hong
Kong are also potential candidates for renewable energy systems.
|2. Solar and Weather Conditions|
Table 1. Solar conditions in Hong Kong
Table 2. Average temperature and humidity in Hong Kong
Average temperature and humidity in Hong Kong are given in Table 2.
With an annual dry-bulb temperature of 23.0 oC, the heating
demand in most buildings in Hong Kong is not significant. The cooling requirements
is large in the summer period which lasts from May to October. The humidity
level remains high in months from February to September and this presents
a need for dehumidification or sufficient ventilation in most buildings
in order to maintain human comfort.
|3. Major Constraints|
Despite of the difficulties mentioned before, the Hong Kong Government
has tried to use and explore solar energy systems in their premises since
1980. The purpose is to collect performance data and build up experience
from the completed installations before the economic advantage of the solar
systems can be justified in a business environment. In recent years, a
few large-scale projects for solar thermal systems have been completed
to demonstrate the importance of such applications and to change people's
|4. Solar Thermal Applications|
Table 3. Examples of large-scale solar thermal applications in Hong Kong
||A hotel and office complex in Tsimshatsui facing Victoria Harbour (* by a private developer)||280 nos. of flat-plate collectors each 900 mm x 2130 mm
||A drug addiction treatment centre on a remote island (Hei Ling Chau)||400 m2 of flate-plate collectors and two 16,000 litre solar water storage tanks|
||A prison on Lantau Island (Shek Pik)||450 m2 of flate-plate collectors and five calorifiers of capacity 36,400 litres|
||A hospital in a new town (Tuen Mun)||96 m2 of solar panels designed to serve a hydrotherapy pool
||A swimming pool complex in a town area (Kwai Chung)||168 nos. of solar panels with total 330 m2 to support swimming
||A new slaughterhouse in rural area (Sheung Shui)||450 nos. of solar panels to provide hot water for processes
Experience showed that putting solar installation into a new building usually is more favourable than retrofitting an existing building because the cost of retrofitting in framing and plumbing may be much as the cost of the collectors for a small project. Sizing the pipework and circulating pump accurately can reduce the operating cost. To avoid waste of thermal energy, insulation should be designed properly. Proper operation and maintenance of the installation are critical to generating of energy and cost savings from the system.
Apart from government projects, a few private buildings in Hong Kong have tried to install solar thermal systems for generating hot water. Their considerations for economic justification are important and this is usually met by matching solar heat with sufficient hot water demand, such as in hotels and youth hostels.
To improve the efficiency of the system, other measures or technologies may be utilised to compliment the solar heat, such as the use of heat pump or heat recovery systems to reclaim heat from the air-conditioning plant so as to raise water temperature in the hot water system (see Figure 1). An integrated approach to designing of the building energy systems is important for achieving an optimal design solution which minimises total non-renewable energy use. A careful understanding of the cooling and heating demands is necessary for designing and matching the system components. This will help lower the capacity and initial investment of the systems.
Figure 1. Solar thermal system integrated with heat pump chiller for hot water generation
A pilot scheme on a PV system for lighting has been carried out in the
Kowloon Walled City Park which is a public park located in the middle of
the city. Other PV applications are being investigated in some research
projects of the local universities. Unlike western countries, PV applications
on rooftop and open space are limited in Hong Kong, except for a few rural
areas. Effective strategy and technology are needed to apply PV in the
urban environment so that high-rise buildings in Hong Kong could benefit
from renewable energy supply.
A weather station powered by photovoltaic panel
PV research at a university in Hong Kong (Photo: H X Yang)
The concept of building-integrated photovoltaic (BIPV) system is believed to be a potential area for solar applications in Hong Kong because it can fit PV cells or panels into the building components such as building facade, shading device and roof. By combining the functions of the PV panels, the overall investment of the system can be reduced significantly. To put this concept into practice, the Hong Kong Government is planning in the year 2000/2001 to install PV systems on two government office buildings which have curtain wall construction in their building facades. The electricity from the PV panels will meet part of the electrical energy demands of the buildings.
As the costs and space for battery storage often create difficulties
to PV system design, pilot research is being carried out to investigate
how grid-connected PV systems can be used in Hong Kong to eliminate the
need for battery storage. Connecting PV or other renewable energy systems
to the electricity grid requires the cooperation of the power companies.
Current electricity regulations and the control scheme between the Government
and power companies will have to be reviewed so as to arrange for effective
power generation, distribution and purchasing. The possible control problems,
local pollution and the effective use of land have to be considered when
making the final decision.
|6. Government Policy|
Among the various agenda items, renewable energy is one of the key issues
that most people agreed to pursue unanimously. The major question at this
point is to investigate the most suitable renewable energy for Hong Kong
and build up skills and experience for its development, design and operation.
Bear in mind the social and economic conditions of Hong Kong, it is important
to recognise that solutions to the energy problems are not simply a matter
of applying technology and enforcement through legislation. It requires
public awareness and participation as well. Therefore, measures to promote
public awareness and education are crucial for the implementation of the
renewable energy policy.
|7. Relationship with Mainland China|
It is clear that China is keen to develop renewable energy (Lindley, 1998). For example, in the coming years, the largest solar product manufacturing plant in China will be built in Shenzhen (through joint venture with a French company). If Hong Kong could play an active role in promoting renewable energy development in mainland China, such as by serving as a financial intermediary and an information and technology gateway, then good business opportunities and industrial development may be generated.
An interesting example of such collaboration is a "solar-powered air-conditioning"
project in Jiangmen City, near Guangzhou in southern China (Wolin,
1998). A university professor from Hong Kong has been the project leader
working with colleagues at Guangzhou Institute of Energy Conversion to
design and implement this innovative project.
|8. Future Prospects|
In medium to longer term, solar thermal and photovoltaics should play a more important role in meeting Hong Kong's energy demand. Opportunities in other renewable areas such as wind energy, small hydro, solar hydrogen, and biomass should be evaluated to identify potential niche markets for their application. Knowledge and skills about the renewable energy systems is useful for promoting them in mainland China, even though they might not be applied in Hong Kong.
Another related area is the Asia's largest refuse incinerator that the Hong Kong Government is planning to build in the coming years. Although the purpose of the incinerator is to reduce the volume of waste in Hong Kong, useful heat/electricity can be produced by the waste-to-energy facilities.
Experience in USA and Europe indicates that the role of utility companies
is quite important for renewable energy deployment. With a world-wide trend
for utility deregulation, it is necessary to review and redefine the role
of Hong Kong's utility companies so that, instead of creating barriers
to private renewable generation, they could make active contribution to
the "solar business" in the energy market.
Interesting suggestions for using solar systems have been raised in
the community. For example, it was suggested to build solar and wind energy
systems in the "Hong Kong Disneyland"; a holistic approach for designing
solar systems in the new towns was proposed; highways and tunnels may be
lit and ventilated by a renewable source of energy; solar-powered streetlight
systems may be widely adopted. More research and innovation are needed
to examine and identify suitable design options. Partnership between Hong
Kong and mainland China will open up a new era for achieving sustainable