Commentary: Why hasn’t solar energy in Singapore taken off in a big way after so long?
Transitioning to solar energy will support Singapore’s climate change mitigation goals but cloud cover, space constraints and technological constraints pose challenges, says NUS Energy Studies Institute’s Philip Andrews-Speed.
SINGAPORE: In 2016, the Government issued its Climate Action Plan which included a commitment to reduce the intensity of greenhouse gas emissions by 36 per cent from 2005 levels by 2030, and for these emissions to reach a peak at around 2030.
Early last year, it made a further commitment, aiming to halve the level of peak emissions by 2050 and achieve net-zero emissions “as soon as viable in the second half of the century”.
Among other measures, this will require the country to reduce its dependence on fossil fuels, notably in the production of electricity where more than 95 per cent is produced by natural gas.
Singapore’s options for domestically generated low-carbon electricity are relatively limited.
READ: Commentary: Singapore’s dreams of becoming a solar-powered nation have almost arrived
There is insufficient wind for wind power, the rocks beneath us are not hot enough for commercially viable geothermal energy.
Tidal and wave energy have theoretical potential but Singapore’s maritime space is too busy with shipping, and nuclear energy is considered too risky for Singapore even with today’s technology
Therefore, solar energy is the most viable option and solar photovoltaics is the current prevailing technology. This why the Minister for Trade and Industry Chan Chun Sing in October 2019 identified solar energy as one of the “Four Energy Switches”.
Solar energy also improves the country’s security of energy supply as it is produced within Singapore. In contrast, all natural gas is imported.
Listen to Philip Andrews-Speed also tackle how Singapore's import of electricity from Malaysia will work and its implications on CNA's The Climate Conversation:
SOLAR IS PICKING UP, BUT SINGAPORE’S AMBITIONS REMAIN MODEST
Solar photovoltaic panels (or modules) consist of a number of cells composed of semiconducting materials that convert sunlight into electricity through what is known as the photovoltaic effect.
Although the mass production of photovoltaic cells dates back 40 years, the extensive deployment of solar photovoltaic panels around the world only really started to pick up from about 2010.
Since then the global installed capacity has risen 17-fold. One of the reasons for this recent surge of capacity is that the cost of photovoltaic panels has declined to about one-tenth of what it was in 2010.
Singapore’s deployment of solar photovoltaic panels at significant scale started in about 2009 and accelerated from 2015.
READ: Explainer: The impact of power on our environment
By September 2020, the total installed capacity was 400 MWp (MWp is the power output of a solar power system which would be achieved under ideal conditions).
But this is still only a tiny fraction of the country’s total power generating capacity of 12,600 MW. Furthermore, solar power is variable unless accompanied by energy storage and so it contributed only about 0.55 per cent of the country’s total electricity supply in late 2020.
The current objective is to boost the installed capacity of solar photovoltaics to 2,000 MWp by 2030. This would provide the equivalent of 4 per cent of Singapore’s electricity at today’s level of demand.
But, of course, the country’s demand for electricity is likely to continue growing, not least as we electrify road transport.
This leads to the question of why these ambitions are so modest.
THE PROBLEM WITH CLOUD COVER
The constraints to Singapore’s ability to host a substantial solar photovoltaic capacity arise primarily from the limited availability of two natural resources about which we can do little: Sunlight and space.
READ: Commentary: Importing electricity from Malaysia is a good thing
On top of these are a number of technological issues that can be progressively addressed.
Although Singapore’s climate is relatively hot and the weather is usually sunny, the average intensity of solar radiation across a full year is not very high. Certainly it is 50 per cent higher than that in northern Europe where solar photovoltaic plays a significant role, notably in Germany.
However, it is significantly less than that in northern China, and 30 to 40 per cent less than in the deserts of North Africa, the Middle East and Australia where vast solar photovoltaic arrays are being constructed.
Singapore’s problem is cloud cover and humidity, as it is across much of Southeast Asia. In addition, the consistently high temperatures reduce the efficiency of photovoltaic cells.
SINGAPORE DOESN’T HAVE ENOUGH SPACE
Space is the second key constraint. Singapore lacks vast open spaces in which to build large solar arrays. Much of the land here is occupied by buildings, roads and protected green spaces.
Today about one third of the country’s solar energy capacity sits on the rooves of residential buildings, while most of the rest is on public space developed by town councils and grass root units. Industrial buildings account for only just over 10 per cent of this capacity.
Last year saw the publication of an updated roadmap for solar photovoltaic energy produced by a consortium led by the Solar Energy Research Institute of Singapore (SERIS).
This detailed analysis concluded that the total usable space for solar photovoltaic panels amounted to just under 37 sq km.
Of this, 62 per cent would be on buildings, both roof space and facades. The balance would be shared between temporary land-based installations (temporary because the land is zoned for other uses), floating installations on reservoirs and unused near-shore sea areas, and panels installed above land, canals and roads.
Costs will vary between the options, and none are cheap compared to installing arrays on large tracts of unused, open land. This is an important consideration given that Singapore runs a competitive electricity market. However, as the national price of carbon rises, the commercial viability of these options will improve.
The three technical constraints relate to cell efficiency, energy storage and grid integration. The efficiency of commercially available photovoltaic cells currently lies in the range 15 to 21 per cent.
What is also important is that some of the more efficient technologies lose less efficiency as temperatures rise. Looking to the future, we should expect new cell designs to have higher efficiency.
As the total capacity of solar photovoltaics grows, energy storage becomes important. This is because solar energy varies during the day as well as from day-to-day.
Although demand for electricity in Singapore is high from 9am to 5pm when the sun is at its highest, there is also a lower peak of demand in the evening when people return home from work and turn on their air conditioners and other electrical devices.
READ: Commentary: Air-conditioning – the unspoken energy guzzler in Singapore
Batteries and other forms of energy storage will be increasingly needed as the country’s use of solar energy rises to provide electricity in the evenings.
Energy storage will also help with integrating the solar power into the electricity grid. The variability of solar energy, from minute-to-minute as well as from hour-to-hour, can pose challenges to maintaining grid stability as the amount of solar power generated rises.
This should not be a problem in Singapore due to flexibility of the gas-fired power stations, especially if they are backed up by energy storage systems,
LIFESPAN OF SOLAR PANELS, EFFECTS OF CLIMATE CHANGE KEY UNCERTAINTIES
Looking to the longer term, two other issues are relevant. First, the life span of solar panels is generally 20-25 years, if well maintained.
This compares to 40 years for a gas-fired power station. The panels will then need to be replaced and the materials recycled.
Less easy to manage will be possible effects of climate change. Temperatures in Singapore may continue rising which will lower the efficiency of the cells, cloud cover and humidity may increase, and the frequency of powerful storms may escalate.
In summary, there are severe limits to Singapore’s ability to generate significant quantities of electricity from renewable sources, and this will not come without a cost.
READ: In The New Map, author Daniel Yergin takes on energy, climate change and the slow but sure shifts in big power relationships
Nevertheless, the Government is determined to make this effort. However, if the country wants renewable energy to supply a substantial share of its electricity, then this will have to be imported either from mainland Southeast Asia or from Australia.
This takes us back to the announcement in October 2020 by Mr Chan that Singapore would import electricity from Malaysia, starting with a two-year trial.
While this is a nice start, access to substantial quantities of renewable energy will require drawing in hydroelectricity from Laos. Plans also exist to build a cable to bring solar energy from Australia to Singapore.
As a result, Singapore will become increasingly dependent on imported renewable energy rather than natural gas for its electricity supply, though gas is likely to remain important for any years.
Philip Andrews-Speed is Senior Principal Fellow at the Energy Studies Institute, National University of Singapore.