Hong Kong has, for decades, been a majestic international city, thriving and shining on the southern tip of China. Its success can be partly attributed to a world-class electricity supply system, one of the most sophisticated and reliable infrastructures in Asia, if not the world.
As global and local communities aspire and work towards a more sustainable and low-carbon future – and with a population of over 7.3 million living within only 1,105 sq km but consuming over 43 terawatt-hours of power in 2015 – what are the realistic options for Hong Kong when we look to 2030 or even 2050? Undoubtedly, our aspirations must be visionary and yet realistic.
Wind and solar technologies have improved significantly in recent years in terms of cost and performance. Solar panels on land and rooftops are surging by the millions globally. Wind turbine technologies for land-based applications have also matured. The key question is, how viable is it to build solar and/or wind facilities in Hong Kong?
Based on wind and solar resources data from US space agency Nasa, and taking into consideration today’s commercially available technologies, the percentage of land area required to displace all local generation in 2015 would be 54 per cent for solar and up to 270 per cent for wind. Alternatively, if 5 per cent of local generation is to be displaced by solar, we will need about 30 sq km (roughly 2.7 per cent of land in Hong Kong or half of Sha Tin District) of unobstructed space.
Land requirement for power generation is measured by the power density, that is, how much power can be produced in a unit area (watts per square metre or W/m2) by a given generation means. Coal-fired power is around 1,400-2,500 W/m2, gas-fired power about 5,900-14,000 W/m2 and nuclear around 1,100-3,700 W/m2. Solar and wind generation are around 4-16 W/m2.
The numbers probably speak for themselves. With such orders of magnitude of difference, if we want local generation while our land areas are scarce, we will have limited choice. This is one reason why gas-fired generation is considered a viable transitional option, as its carbon dioxide emissions are about half those of a similar coal-fired facility and yet it has a power density higher than coal.
Wind and solar generation are inherently uncertain and intermittent. To maintain a continuous and reliable system, we need the grid connection or local energy storage to back up renewable generation.
For grid connection, often taken for granted, we rely on a supply system that must be highly controllable and yet economic to maintain the power balance. Fossil-based generators are by far the most practical and affordable means unless you have many hydro plants like in Norway. Storage by means of pumped-hydro is by far the most popular and practical. However, it requires the coexistence of suitable terrain, abundant energy at times and available water resources (river or sea).
Today, battery technology for bulk storage is still expensive. According to the International Energy Agency, battery investment cost in 2015 was about US$400-US$500 per kilowatt-hour. Even if we go to 2025, the projected cost will be no less than US$200 per kWh. Innovation and major technological breakthroughs must take place to make batteries the holy grail.
But before such breakthroughs do happen, when we think of wind and solar, we must also think of the times without them. How should the backup system work to ensure continuity of service, high reliability and low cost?
Installing distributed and small-scale solar and wind facilities has also received much attention globally. Existing meters, at least in most residential units, are traditional electromechanical devices with simple capabilities. If widespread installation of solar (or wind) facilities takes place, smart meters with the necessary intelligence would be needed to accommodate the feed-in tariff, which will pay for renewable energy at a higher price.
Some may argue that financial support for feed-in tariffs can come from existing “energy subsidies”. While the energy sector in Hong Kong in general does not receive direct financial transfers or preferential tax treatment, we have yet to understand whether such subsidies really exist in Hong Kong or are calculated fairly. More importantly, we must carefully study what should be a fair feed-in tariff and how often we should revise it; what should be a fair rate of grid connection; and, how building codes should be amended to incorporate more solar rooftops.
The UN-accredited World Energy Council defines a sustainable energy system as one that considers three core dimensions simultaneously: energy security, energy equity and environmental sustainability. These goals constitute a “trilemma” and one must strike a balance among these three goals to ensure a sustainable energy future.
Each year, the council publishes an Energy Trilemma Index report and Hong Kong has always ranked quite high – it was in the top 30 among 130 jurisdictions rated in 2015. We are also within the top five in the Asia-Pacific region. In particular, Hong Kong was ranked eighth globally in terms of energy equity, meaning that we are not only maintaining a good balance in the overall trilemma assessment, but we also excel in making energy affordable and accessible to our citizens.
Energy is a unique industry and is fundamental to the very fabric of society. Our history, culture, available resources, economic strength, technological know-how and social needs are also unique in Hong Kong. We must ensure all stakeholders are reasonably aware of the impact and implications of any policy changes and subsequent developments.
Therefore, our energy vision, road map and targets should also be designed and implemented to strike a balance among the trilemma, considering past global experiences and the future direction of the Chinese mainland.
Dr John W. M. Cheng is general secretary of the World Energy Council – Hong Kong, China, and CLP Research Institute’s senior manager