|Simplified UCG process. Click to enlarge.|
The Government of Alberta, Canada, through the Alberta Energy Research Institute (AERI), is providing C$8.83 million (US$7.0 million) toward a $30-million underground coal gasification (UCG) project with Swan Hills Synfuels of Calgary. Swan Hills Synfuels expects the project to demonstrate the ability to manufacture synthetic gas from Alberta’s coal resources, with the future potential of utilizing the coal seams for carbon capture and storage.
The project in north-central Alberta aims to develop a commercial operation that produces clean, synthesis gas for power generation. The deep formations could also store carbon dioxide after the coal is turned into gas. Underground coal gasification has been used commercially outside of North America for close to 40 years with minimal surface impact when compared to traditional coal mining and production.
In 2007, BP and Lawrence Livermore National Laboratory (LLNL) have signed a technical agreement to work cooperatively on the development of UCG technology for the in-situ conversion of coal deposits into fuels and other products. (Earlier post.)
The project with Swan Hills Synfuels LP is the first of its kind in North America to demonstrate coal gasification at depths greater than 1,000 meters below the surface.
In 2008, Swan Hills Synfuels proposed a UCG project at a cost of C$400-600 million with a nameplate capacity of 3910,000 m3/d of syngas and 2,000 t/d of CO2. The facility is targeted to be at Swan Hills, 250 km north of Edmonton, and near the oil sands projects that are scheduled to demand 1 billion ft3/day or more of gas for fuel. Start-up is planned for 2012. The pilot project consists of a single well pair (injection and production).
Underground coal gasification (UCG) is an in-situ process using injection and production wells drilled from the surface, and enables the coal to be converted into a syngas. (Earlier post.) The process is flexible in operation and is capable of producing commercial quantities of gas to be used like natural gas, such as for home-heating chemical feedstock or as fuel for clean power generation.
The syngas produced by underground coal gasification is amenable to efficient pre-combustion carbon dioxide (CO2) capture, producing a high-purity CO2 byproduct. It may also be feasible to sequester captured CO2 in coal seams depleted by underground coal gasification.
Underground coal gasification does not use fresh water in its operation and is significantly different than other in situ processes, such as those used in oil sands development. Underground coal gasification is used at depths where conventional coal mining is not economic or currently possible.
We have centuries of coal supply beneath our feet and it’s important to examine better ways to use this resource. Alberta has had success with coalbed methane and cleaner coal technology is part of our overall climate change strategy.—Advanced Education and Technology Minister Doug Horner
Linc Update in Australia. Separately (and almost antipodally), Linc Energy Limited in Australia provided an update on its Third Underground Coal Gasification (UCG) generator trial at Chinchilla. (Earlier post.) The project began in August 2008 and has now been operating continuously for almost seven months, making it one of the longest-running western world UCG trials to date.
The operation is air-blown and produces gas at a pressure of approximately 10 atmospheres. No steam or water is currently required to be injected into the process although this can be accommodated if required. The main objective of this trial was to demonstrate the supply of synthesis gas of sufficient quality and quantity for utilization in the Gas to Liquids (GTL) demonstration plant over a lengthy period.
During its almost seven months of operation, the generator has operated very stably, according to Linc, producing gas of consistent quantity and quality. Gas has been produced with a typical composition (on a nitrogen-free basis) of H2 32%; CO 17%; and CH4 18%. The H2/CO ratio of 1.81 is ideal for Linc Energy’s GTL process. Since commencing operation of the Third UCG generator, Linc Energy has gasified approximately 2,000 tonnes of coal, producing more than 5 million Nm3 of synthesis gas.
The information that has been gathered from Generator 3 to date has been used to gain further understanding of the UCG process in order to validate the technology models being developed by Linc Energy and to enable it to predict the performance of commercial scale UCG generators while also enabling the operating conditions of the generator to be effectively controlled.
The extent of the technology modelling taking place includes physical modelling of the generator cavity growth that allows Linc Energy to accurately predict the coal consumption rate over time and link the physical dimensions of the generator with the gasification model, the hydro-geological model and with other physical parameters.
Linc says that it is well advanced with the engineering of Generator 4 that will see commercial scale production rates of up to 5 PJ/annum per UCG generator installed. The most recent learning and technology will also be applied to the design of the reactor and above ground facilities for a Vietnam pilot project.
Work continues to progress on the Vietnam UCG trial project which is a collaboration between VINACOMIN (Vietnamese State Owned Corporation), Marubeni Coal Pty Ltd (Japanese Private Equity Company) and Linc Energy. The site for the trial has now been selected and is approximately 60 kilometers southeast of Hanoi within the Red River Delta.
It is intended that Stage 1 of the program that includes sixty days of gas production will be completed within twelve months. The purpose of this stage is to determine the suitability of the Red River Delta coal for underground gasification. If successful, the companies will move into Stage 2 of the program; being the development of a commercial UCG field to provide syngas for much needed power generation in Vietnam.
Linc Energy now also holds a 74% majority interest in Yerostigaz, a joint stock company located in Angren, Uzbekistan. Yerostigaz has operated continually since 1961, producing syngas for use in the Angren Power Station.
The Yerostigaz UCG operations were commissioned in 1961 and by the end of 1965 it was producing approximately 160,000 m3 of gas an hour (i.e. in less than 4 years the production capacity of 1.4 billion m3 of gas per year was achieved). All gas produced was supplied to the Angren Power Station.
Currently Yerostigaz is meeting its production targets by producing and delivering 1 million m3 of UCG syngas per day, equating to 30 million m3 of UCG syngas per month for the Angren Power Station.