Is burning coal for energy a step backwards from going green?
Singapore’s Non-Constituency MP Sylvia Lim raised that concern in Parliament recently, noting that other countries were moving away from coal because of its environmental impact.
Coal is often thought of as a dirty fuel, releasing excessive amounts of carbon dioxide, sulphur dioxide and other pollutants when burnt. Yet the city-state’s Senior Minister of State for Trade and Industry S. Iswaran, responding to Ms Lim’s question, emphasised that technologies for burning coal were becoming cleaner.
“Precisely because the technology is evolving, I don’t think it is necessarily a step back to consider this as a possible option for ourselves,” he said.
In January, the Economic Strategies Committee had recommended importing coal as an energy source to boost Singapore’s energy security.
The recommendation seemed to clash with the country’s target of trimming its carbon dioxide emissions by 2020 by 16 per cent below the level it would have been if no steps had been taken to cut CO2.
As it is, coal is responsible for a significant share of man-made carbon dioxide emissions around the world. International Atomic Energy Agency figures show that burning coal emits nearly twice as much carbon dioxide as burning natural gas, which Singapore currently relies on for most of its power. (Only about 20 per cent of Singapore’s electricity comes from fuel oil.)
Burning coal for energy produces between 790g and 1,017g of carbon dioxide and equivalents per kilowatt hour (kwh), compared to 362g to 575g per kwh for gas. These figures do not include emissions from transporting the fuels.
But in terms of energy security, however, importing coal for electricity makes sense. It is the cheapest and most widespread fossil fuel, with nearby sources in Indonesia, Australia and China.
And as the Economic Strategies Committee report put it, “advances in combustion technologies are reducing the environmental impact” of coal.
The report did not elaborate on the technologies, but generator technology that converts water to steam under high pressure – supercritical steam generation – is more efficient than ordinary power generation and saves on fuel use, whether it be gas or coal.
In addition, Tuas Power’s upcoming coal and biomass-fired power plant on Jurong Island will use technology that burns low-ash, low-sulphur coal at lower temperatures than normal, which will reduce the amount of sulphur dioxide and nitrogen oxide emitted.
However, even such technology is still not able to reduce the total amount of carbon dioxide released. For this reason, “carbon capture storage technology is still being developed and we may explore the viability of its application in the future”, said a Tuas Power spokesman.
But scholars say carbon capture is an expensive, energy-intensive process, and there is no proven way to store carbon dioxide with no leakage or ill effects.
“Carbon capture and storage, the way it is promoted now, is mainly a myth,” said Energy Studies Institute researcher Hooman Peimani.
He explained that waste carbon dioxide injected into the ground or water will eventually leak back into the atmosphere. Other ideas on the table include using carbon dioxide to grow algae that can then be turned into biofuel, putting carbon dioxide into cement for building, and using enzymes to turn carbon dioxide into bicarbonate. But all these ideas are still in the realm of speculation.
Others, like Energy Studies Institute scholar Michael Quah, believe coal should not be ignored just because carbon capture and storage has not been proven to work. On the contrary, Dr Quah said, that provides more incentive for Singapore to do research into better technology.
“I believe this is one area where we could truly take the lead,” he said.
Instead of capturing all carbon dioxide emissions from coal, Dr Quah argued, Singapore should work on reducing coal emissions so that they are on a par with those from natural gas – the so-called natural-gas parity.
The cost of doing this would be far less than full-blown carbon capture and sequestration, and would not use technologies still being evaluated, he explained. That would in turn buy Singapore some time to increase energy efficiency and eventually transition to renewable energy over the long run, impelled by the price of carbon.
The energy landscape must be viewed as a whole, Dr Quah urged, rather than piecemeal, fuel by fuel.
But in all the discussion of clean coal technology, one thing has perhaps been overlooked: the very process of extracting coal and other fossil fuels is polluting. Their polluting impact does not derive solely from the carbon dioxide released when they are burnt for use.
Coal mining, for example, itself releases the greenhouse gases carbon dioxide and methane, and can contaminate water sources with acid runoff and heavy metals. In Indonesia’s coal-rich South Kalimantan, for instance, strip mining causes erosion and land degradation.
So to truly assess fuel sources as a whole, one must look at their impact throughout their life cycle, from extraction or production to burning.
By that consideration, natural gas can be as destructive as coal. It is extracted from natural gas fields, or as a by-product from oil fields or coal beds.
In the United States, oil and gas companies using the deep-drilling technique to extract gas, called hydraulic fracturing or fracking, have come under government scrutiny for the toxic chemicals used: They can pollute groundwater.
As Dr Peimani put it: “The effort should be made globally to decrease, and eventually phase out fossil energy as the main source of energy, not to switch to more pollutive types of fossil energy.”