Carbon sequestration, also known as geosequestration, seems like a good deal. "Have your carbon cake and eat it too." In principle, it works this way: You capture CO2 emissions at the source before they are released into the atmosphere, compress them until they become liquid and then inject them in deep underground holes. What could be simpler? It certainly sounds like a good tool to fight global warming while enjoying the Earth's huge coal reserves.
I used to think that it would indeed be one of the many solutions used to save ourselves from catastrophic climate change, but not anymore. In fact, I now think that it might be a counter-productive red herring. What has made me change my mind? What's the problem? Read on, please.Tim Flannery, in his highly recommended book The Weather Makers, dedicates a chapter to engineering solutions to global warming. In it, he gives an overview of carbon sequestration technology, the problems that have to be solved before it can work, and what the coal industry has been doing so far.
Here are the problems in order:
First, from the smokestack:
The stream of CO2 emitted there is relatively dilute, making CO2 capture unrealistic. The coal industry has staked its future on a new process known as coal gasification. These power plants resemble chemical works more than conventional coal-fired power plants. In them, water and oxygen are mixed with the coal to create carbon monoxide and hydrogen. The hydrogen is used as a fuel source, while the carbon monoxide is converted to a concentrated stream of CO2. These plants are not cheap to run: around one-quarter of the energy they produce is consumed just in keeping them operating. All indications suggest that building them on a commercial scale will be expensive and that it will take decades to make a significant contribution to power production.
So about 25% of the energy they make is used just to keep them operating, they are more expensive and it will take decades (an amount of time we don't have) before they make a significant contribution. Meanwhile, old coal power plants have an average lifetime of 60 years.
Let's assume that some plants are built and the CO2 is captured. For every tonne of anthracite [coal] burned, 3.7 tonnes of CO2 is generated. If this voluminous waste could be pumped back into the ground below the power station it would not matter as much, but the rocks that produce coal are not often useful for storing CO2, which means that the gas much be transported. In the case of Australia's Hunter Valley coal mines, for example, it needs to be conveyed over Australia's Great Dividing Range and hundreds of kilometres to the west. [pipelines cost about $1 million per mile, more when terrain is rough and uneven.]
Once the CO2 arrives at its destination it must be compressed into a liquid so it can be injected into the ground--a step that typically consumes 20 per cent of the energy yielded by burning coal in the first place. Then a kilometre-deep hole must be drilled and the CO2 injected. From that day on, the geological formation must be closely monitored; should the gas ever escape, it has the potential to kill. [...]
The largest recent disaster caused by CO2 occurred in 1986, in Cameroon, central Africa. A volcanic crater-lake known as Nyos belched bubbles of CO2 into the still night air and the gas settled around the lake's shore, where it killed 1800 people and countless thousands of animals.
Okay, so even more energy is lost by compressing the CO2 to liquid form and we must monitor for leaks. What else?
Earth's crust is not a purpose-built vessel for holding CO2, and the storage must last thousands of years so the risk of leak must be taken seriously.
Even the volume of CO2 generated by a sparsely populated country such as Australia beggars belief. Imagine a pile of 200-litre drums, ten kilometres long and five across, stacked ten drums high. [1.3 billion drums] Even when compressed to liquid form, that daily output would take up a cubic kilometre, and Australia accounts for less than 2 per cent of global emissions! Imagine injecting 50 cubic kilometre of liquid CO2 into the Earth's crust every day of the year for the next century or two.
If geosequestration were to be practised on the scale needed to offset all the emissions from coal, the world would very quickly run out of A-grade reservoirs near power stations and, especially if the power companies are not liable for damages resulting from leaks, pressure would be on to utilise B, C, D and E grade reservoirs.
Okay, so burying it in the ground is not so simple or safe - as the oil industry likes to remind us, drilling is expensive - and it's not a long-term solution since we will run out of convenient places to sequester the liquid CO2. Anything else?
All of this suggests that the best case scenario for geosequestration is that it will play a small role (at most perhaps 10 per cent by 2050) in the world's energy future.
Because action is needed now to combat climate change, both the public and the marketplace need to see proof of geosequestration's potential. Big coal should already be building trial coal gasification plants with geosequestration as a test of the economic and technological viability of their approach. Yet, despite offers of government assistance, very little is happening with geosequestration. [...] Imagine the cost of building the new generation coal gasification power plants, the separation, storage, pipelines, compressors and injection wells.
So they're not even rushing to test it and make it happen?
Politicians have been seduced by the coal industry's spin. [...] the Australian government set up [behind closed doors] a $500 million research fund for low emission technologies, precisely tailored in its brief to accommodate geosequestration. That's half a billion dollars that will never be fairly shared between all energy options to ensure the best outcome for the nation. [...]
What is at stakes is [...] that Australia must increase its power production by more than 50 per cent by 2020 (a slow rate of growth compared with China [the biggest coal user in the world]), and the coal industry would like to secure as large a share of the cake as possible.
All this talk of carbon sequestration can basically be seen as a delaying tactic, as a way to get government support and to keep the operation and construction of coal power plants more socially acceptable. It's the equivalent of saying: "Don't bother us, we're working on it!"
But even if we suppose that big coal starts to build the expensive gasification plants soon and that they can solve most of the technical problems with geosequestration, they are not saying that they want to replace old, extremely dirty plants with the new ones; they want to build new ones and keep the old ones. They almost certainly won't bear the liability of CO2 leaks from underground storage, so that's an extra cost for taxpayers, not to mention that the electricity coming from coal gasification plants that do carbon sequestration will be more expensive because a lot of energy is lost in the process of running the plants, in the actual sequestration operating, and the huge costs of building the pipelines, the plants, drilling the holes, maintenance & monitoring, etc, will be passed on to the customers (or they'll ask for subsidies - same difference).
So it'll take decades which we don't have, be extremely expensive, probably won't work that well, and we'll run out of good burying sites before long. Meanwhile, the clean energy industry (solar, wind, wave, geothermal) will keep growing very fast at exponential rates, their costs will keep going down and the efficiency of their production units (wind turbines, solar panels, hydrokinetic buoys, Gorlov helical turbines, geothermal heat pumps) will keep going up.
The fastest and cheapest way to close down coal plants soon is probably investments in efficiency. Remember, it's a lot cheaper to save a watt of electricity than to produce one.
society civilization species, we must back the right horse and stop being misled by the coal industry's delaying tactics. There's a big opportunity cost in time and resources to going down the wrong path. Each new power plant big coal builds means decades of fat profit for it, but for the rest of us here on Earth, it's just bad, bad news.
Read: The Weather Makers by Tim Flannery.