Wednesday, November 12, 2008

Carbon Capture and Storage or has Elvis already left the building?

Excert from ZERO Greenhouse Emissions - The Day the Lights Went Out - Our Future World Chapter 4 - The Day Before

The coal industry and the political parties supporting them would have us believe they can continue with the fossilized carbon release and offer up for our comfort, the silver bullet, of “Clean Coal Technology” and “Carbon Capture and Storage—CCS.”
Digging deeper, as they also must to keep up with exports, we find the plot thickens.
First to the basics: Coal is formed in ecosystems where the remains of plants were preserved by water and mud from oxidation and biodegradation, thereby sequestering atmospheric carbon. As over time geological processes apply pressure to the dead matter, under suitable conditions, it transforms successively into peat, lignite (also referred to as brown coal), sub-bituminous coal, anthracite, and graphite.
Lignite, sub-bituminous coal and bituminous coal are used for coal-fired energy generation, with the higher grade, bituminous, also used for manufacturing, steel production, and to make coke (not the kind you drink). Coal is mostly used to produce electricity, and the world’s annual consumption is presently around 6.2 billion tonnes, with estimates that 75 percent of this figure or 4.65 billion tonnes is used to produce electricity in the world’s coal-fired power stations. By 2020, a 50 percent projected increase in global demand will put consumption up to 9.3 billion tonnes annually.
Does anyone apart from me see the correlation between coal use and escalating greenhouse emissions over the period from now until 2020? Logic suggests, if we want to stop global warming, stop coal!
China produced 2.38 billion tonnes in 2006, while also being a net importer of coal including supplies from Australia. As an aside, in January 2007 the Australian federal government committed A$100 million to a partnership resoundingly welcomed by the Australian Coal Industry, called the “Australia–China Joint Coordination Group on ‘Clean Coal Technology.’”
Just over 83 percent of China’s electricity comes from coal-fired power stations and this is on the rise. The United States consumes about 1.053 billion tonnes using 90 percent of this for energy generation.
So back to the helpful suggestion from the Australian Coal Industry Association: It’s not the use of coal that’s the problem, but how coal is used!
When coal is consumed in coal-fired power plants, it is usually pulverized and then burned in a furnace with a boiler. The furnace heat converts boiler water to steam, which is then used to spin turbines that turn generators, and creates electricity. The efficiency of this thermodynamic process of steam turbines is at best 35 percent. Many older plants presently in service are significantly less efficient. What this means at best though, is that 65 percent of the coal energy is waste heat released into the surrounding environment! That translates into over 3 billion tonnes of the 4.65 billion tonnes burned for energy generation annually being wasted! The energy density, or the heating value, of coal is roughly 24 megajoules per kilogram (3.6 megajoules = 1 kilowatt) coming out at 6.67 kilowatt hours per kilogram. When the average 30 percent thermodynamic efficiency is factored in, coal-fired power plants at best generate two kilowatt hours per kilogram of burned coal. As coal is at least 50 percent carbon by mass, then there is 0.5 kilogram of carbon in 1 kilogram of coal. This ½ kilo of fossilized carbon when combusted combines with oxygen in the atmosphere, producing carbon dioxide, resulting in a combined weight of carbon plus oxygen, of 1.83 kilograms of CO2 for each and every kilo of coal burned!
So from burning coal for energy generation alone, at present rates we add 8.51 billion tonnes of CO2 to the atmosphere each year. On average to produce 1kilowatt of electricity, a coal-fired plant will spew out close to 1 kilogram of CO2.
I guess the industry and its supporters can happily justify the green wash term, “Clean Coal,” and the projected increase in coal-fired energy generation by 2020 to producing 12.77 billion tonnes of CO2 in global atmospheric pollution annually.
When approached to justify how they can continue to promote coal use for energy generation and at the same time reduce the resultant heat-trapping carbon dioxide levels in the atmosphere, in order to return the planet to a safe and habitable world, they will trot out “Carbon Capture and Storage—CCS.”
The premise being, we can continue to generate energy from polluting nonrenewable sources by the burning of fossil fuels, as long as when we intentionally release the trapped carbon, we run around and catch it before it leaves the building!
Over the coming years there will be a great deal of investment in CCS. Billions of dollars of public funds, your money and mine, will be directed to it. Some would argue that CCS is a convenient diversion by the pro-coal lobby. Some would say the investment would be better placed to fast track renewable energy supplies and increase energy efficiencies. The European Union and the United Nations Climate Panel along with many researchers, place high hopes on the development of CCS. Indeed many of their hopes and much of their forecasting for emissions reductions over the coming years rely heavily on the success of the technology and its wide deployment. By 2020 the EU has committed to overall CO2 emission reductions of 20 percent, but plans to construct 50 new coal-fired power plants by 2013.
CCS, while technically feasible, according to industry experts (can we trust these guys?), is expensive, while decreasing the average efficiency of power plants by up to 20 percent, and so far globally there are only a smattering of small “demonstration projects.” In Norway they are demonstrating they can capture and store a million tonnes of carbon dioxide per year. Do the numbers add up? 12.77 billion tonnes of CO2 from coal-fired energy generation by 2020? Retrofitting the over fifty thousand coal-fired power stations presently operating globally—and rising? Various scenarios put forward by its supporters suggest that CCS could account for between 15 and 55 percent of the reduction of greenhouse gases by 2100.
The International Energy Agency estimates that world energy demands will soar by 60 percent from current levels by 2030, with 85 percent of that being from the burning of fossil fuels. It reports that Germany is planning twenty new plants in the coming decades while China is expected to install a further 800 gigawatts of new electrical power capacity by 2015, of which, 90 percent will be from coal. The IEA highlights that 800 gigawatts is equivalent to all the power capacity installed throughout the European Union member countries since 1945.
So how do we catch Elvis before he leaves the building? Some researchers studying CCS point out themselves that their models and scenarios in many respects are based on insufficient factual foundations, unrealistic assumptions, and major oversimplifications. One report by Anders Hansson of Linkoping University Sweden states: “In full scale this technology only exists in the imagination of the people developing it and that it is overly optimistic to place such great faith in CCS considering all the uncertainties found in current scientific literature.” Is it a diversionary tactic by those with vested commercial and political interests wishing to continue down the fossil fuel burning path? By the coal industry lobby and suppliers, who will benefit while we blindly follow them down this well-trodden proven path of pollution? Is it politically easier to offer hope to us that a solution may be found, so that all of us can keep the energy consumption drug we are addicted to? Do the numbers add up? To live up to the hopes placed on CCS requires the storage of billions of tonnes annually, meaning carbon dioxide would become the world’s largest transported good.
But there is another complication. Some may suggest that it means that CCS, even if successfully developed and deployed to all the coal-fired power stations in the world, would save such a minuscule amount of the CO2 pollution resulting from the process of extraction and burning coal, that it is a thorough waste of time and of the billions that will be spent in coming decades.
It again comes back to externalities. It is the hidden environmental consequences resulting from the very process of getting the coal out of the ground.
If we revisit the basics: coal is formed in ecosystems where the remains of plants were preserved by water and mud from oxidation and biodegradation. Over time geological processes apply pressure to the dead matter and under suitable conditions, it transforms into coal.
The fact is that coal mining doesn’t just dig up the coal. Mining the volumes now consumed around the world means that most coal today comes from opencast–open pit coal mines. As we know, methane, carbon dioxide, and carbon monoxide (the stuff that kills the canary!) is released in the process. These emissions start as soon as the layers above, called the overburden, are stripped away.
The damage starts right then.
Conservative estimates from experiments going back as far as the 1960s and reported by Brame and King in Fuel, show that these gases alone account for about twice the emissions of the burning of the coal that has been mined. In other words, for every 1 kilogram of coal burned, producing 1.83 kilogram of CO2, a further 3.66 kilograms of CO2-e emissions result.
And again, back to the basics; not all that is disturbed, or dug up, is coal. In fact, around 98 percent of what is mined is not coal. A large portion, on average 25 percent or ten times the amount of coal that is extracted, will be shale and mudstone, with a carbon content of 50 percent of that of coal, in other words, the carbon content by mass of 250 grams per kg. So 1 kilogram of successfully mined coal (50 percent carbon by mass or 0.5 kilogram of carbon), has an externality in unwanted mudstone and shale of around 6.25 kilogram of carbon. This shale and mudstone cannot be burned due to its high ash content, but it still oxidizes if exposed to air, producing CO2. These along with other unwanted workings are tipped as part of the mining process waste. Again, conservative estimates give this carbon source the potential to emit three to four times as much CO2 as the mined coal.
So if we revisit the question as to the value of investing in carbon capture and storage at the power station, we see that if successful these would account for a result of between 5–10 percent maximum of the emissions attributable from the process of working/mining and burning coal. Personally, I think Elvis has left the building!