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Friday, 3 July 2009

The case for coal?

An interesting piece by the aspiring MMD presidential candidate Clive Chirwa on Zambia’s alternative energy sources:

Our country is well blessed with enormous quantities of a variety of natural resources. Unfortunately, oil is not one of them. Specialists in oil prospecting say that Zambian reserves are in very small pockets making its production difficult and in economic terms commercially unbeneficial. Others argue that the oil basins, if exist, are just too deep for current equipment to detect and therefore will never be brought to the surface for many decades to come.

Whether we have oil or not we really have to look at a cheaper alternative that can work for us today as the cost of oil from the Middle East creeps up while our revenue diminishes.

The choice is the Underground Coal Gasification (UCG). This converts coal in-situ into a gaseous product commonly known as synthesis gas or Syngas through chemical reactions. Advantages of UCG are that the whole process is carried out underground. This eliminates the mining operation costs, damage to the environment, and no surface gasification systems are needed, hence, capital costs are tremendously reduced. The process itself relies on the natural permeability of the coal seam to transmit gases to and from the combustion zone. As a result gasification converts hydrocarbons into syngas at elevated pressures and temperatures and can be used to create many products namely electric power, chemical feedstock, liquid fuels, and hydrogen.

Zambia has a lot of coal, especially the low grade reserves that can be used in UCG. We need to quickly start using this method. Currently, South Africa uses the surface gasification system for some of its power. This is more expensive than underground coal gasification because of the industrial plant needed to be built on the surface. In principal the process is not very different from what we currently use in making our “malasha” charcoal. Only that we built an artificial kiln on the surface pump it with wood, create a combustion and chemical reactions are attributed therewith. Our experience coupled with what other countries have had can help us quickly tap into this cheap energy generation process.

The USA has over the years from 1975 to now carried out over 30 pilot tests on bituminous, sub-bituminous and lignite coal. The pioneers though are the Russians who have over 50 years of experience in UCG and have had very successful working commercial projects, the biggest being the electric power plant in the now independent Angren, Uzbekistan. China has also jumped on the band wagon and has executed at least 16 test UCG projects for chemical and fertiliser feedstock. In year 2000, Australia began a large pilot UCG plant at Chinchilla which produces syngas. Current developments show that Canada, India, New Zealand and South Africa have signed up to develop UCG so that they can produce liquid fuel and synthetic natural gas. This is what we need to do in Zambia and on the back of syngas even have electricity. This process kills two birds with one stone so to say. On one side, we get the liquid fuel we need and on the other also get electricity from the same operation.

The economics of UCG are extremely promising for Zambia. The capital expenses of UCG plants are substantially less than the equivalent plant fed by surface gasifiers currently used in South Africa for example. Similarly, operating expenses are much lower because of the lack of coal mining, coal transportation, and significantly reduced ash management facilities. Even for configurations requiring a substantial environmental monitoring programme and additional swing facilities, UCG plants retain many economic advantages.

In addition, what we need to understand is the risk assessment in UCG. Environmental risk assessment for UCG has unique aspects, requiring consideration of a complex array of changing conditions, including high cavity temperatures, steep thermal gradients, and stress fields obtained during and after the burn process. In the context of the site stratigraphy, structure and hydrogeology, risk models must evaluate the permeability changes from cavity development and collapse. If controlled, there is no problem.

In Zambia, the UCG appears to be commercially ready in many context. We can join the hundreds gasification plants constructed around the world producing the equivalent of 50,000 MW (thermal) of syngas. Our national economy is growing steadily, limited only by the availability of energy and current infrastructure. So far have insignificant power consumption from coal despite having huge reserves. We can use the low grade coal around Mumbwa region that gives us between 30-35 per cent ash content. Indeed the UCG is appropriate for our deep unmineable coal seams and are potentially well suited for producing synthetic gas for power generation and liquid fuel for propelling vehicles.

In addition our coal using this same process can be a source of hydrogen production, especially in the light that future engines will use hydrogen as propelling fuel. The proposition of a hydrogen economy relies on affordable hydrogen with significantly reduced near-zero emissions. UCG is a proven technology, albeit only in the initial stages of commercialisation outside Russia that has used it for over 50 years with very few problems to write home about. We too can benefit.

5 comments:

  1. Has there been any thorough exploration in Zambia with respect to oil and coal resources for Chirwa to reach these conclusions? It will be helpful if he were to give us the data. What is the quantity of oil in these 'small pockets'? I am sure the 'specialists' he has alluded to must have the numbers. And where exactly are these pockets? My take on this is that we simply do not know.
    Lastly, Prof Chirwa must have a very good sense of humour! Quote: "Others (oil specialists)argue that oil basins, if exist, are just too deep for current equipment to detect and therefore will never be brought to the surface for many decades to come" Lol. Prof Chirwa seems to be suggesting two contradictory things i.e Zambia either has oil in small pockets and/or in the event that Zambia has oil then it is too deep to be drilled. Conclusion: The Prof does not know what he is talking about!

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  2. Frank,

    lol!

    Well observed. I was equally puzzled on how he had reached the conclusions on oil.

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  3. Speculations on the size and location of oil deposits aside (the whole industry is a gamble from what I can tell), the proposed alternative use of coal beds for underground gasification rather than traditional mine extraction and combustion is intriguing given that the country is pushing the limits of how fast hydropower can grow. Of course we should not be persuaded into thinking that this is "clean coal", nobody has gotten there yet, but it is certainly "cleaner" and predictably more expensive than traditional electricity provided by coal.

    The US is very keen on this technology, being as the country has some of the largest coal reserves in the world, so here's the page from the Department of Energy site devoted to the subject (these are state projects, not federal, so the political aims of research and/or reporting may be different in some cases, salt recommended.). US public research on gasification.

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  4. Oh and I almost forgot! The arbitrary Blogger.com limits on comment length are both unnecessary and annoying!

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  5. This is not mature technology and therefore has a high risk profile. I would suggest to go with conventional coal mining and ordinary coal power station.

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