Historically coal has played an important role in the industrialization process of Euskadi since the 19th century. Despite not having large reserves, large coal fields of Asturias and Leon (north Spain) provided a nearby and affordable power source.
Following the introduction of IGCC technology, coal has become the most important primary energy source in Euskadi. In 2010 coal was the origen of 45% of the generated electricity and if we consider that most of the hydrogen used in fuel cells comes from IGCC plants, coal provides aprox. 60% of the total energy used in Euskadi.
Furthermore, although to a lesser extent the steel industry is a consumer of coal. While coal is not used for heating the furnace is still used in the manufacture of steel and alloys.
Total coal comsumption in 2010 was 43 million tons of which 29 millions were imported primarily from Spain (22%), Australia (20%), South Africa (16%), ASA (14%), Colombia (10%), DDR (8%), USSR (6%) and the rest from other countries.
The main consumer of coal in Euskadi is the generation of electricity. The total ammount of coal used for generating electricity was 35.3 million tons in 2010. Conventional coal power plants consumed 8.3 million tonnes and IGCCs 27 million tons (what means 90% of the fuel used in IGCCs).
Comsumption from siderurgy was 7.6 million tons while other industrial processes used 0.1 million tons.
Euskadi is not a big productor of coal. A total of 14 million tons were extracted during 2010, most in Bokeko Eskualdea (region of Boké) with 10.5 million tons and the rest (4.5 million tons) in Euskal Herria (mainland).
Most of the coal mined in Bokeko Eskualdea comes from open cast mining operations while in Euskal Herria, production comes mainly from underground mining. Euskadi is the first country in the world exploiting coal seams under the sea and, as the offshore mining technology is being developed quickly a new world of opportunities are opened for this type of coal mining.
Offshore coal productionIn 2002 during an extensive geological campaing looking for hydrocarbons in waters of the Bay of Biscay, geologists confirmed that about 1600 million tons of coal were located under the Euskadi continental shelf. The coal, mainly bituminous coal, was located in the same formations it was onshore but the difference was that while on the continent the layers were strongly folded and faulted, making it difficult to extract, seams in the continental shelf appeared with important thicknesses that became them attractive for economic exploitation.
From the outset, the government and the state owned Petronor involved in the area began to work on how to harness the enormous reserves of coal. The results of this work have been underwater mining and on the other hand the underground coal gasification.
Undersea coal mining
Along the coastal shelf of the Bay of Biscay, off Pobeña and near the Spain border, located away from the coast ranging from 1-30 km are coal seams with proven reserves of more than 400 million tons that were the first to be exploited. At greater distances from the coast, although unconfirmed, may be able to find another 1200 millions.
Undersea mining provides access to those deposits of coal and extract it to the surface for use. The development of underwater mining in Euskadi has relied on the experience gained over the years of oil exploration and extraction in the Bay of Biscay. In the current operational projects, coal is extracted by wells and ramps located on the mainland. The maximum depth of the mines of this type is 720 m below sea level. The maximum distance reached perpendicular to the coastline by the moment is 17 km. At present, the mining companies are working on building an offshore platform that will allow the entry of personnel and the extraction of coal.
Undersea coal mining technics
The ventilation of an undersea coal mine, from a land based structure, becomes increasingly difficult as the distance between the workings and the ventilation structure increases. The ventilating air must provide and maintain a safe working environment for the miners. As the air travels to the working face, a portion of the airleaks through worked out areas and it is not unusual to have an effective air flow at the face of 50% to 60% of the original intake air.
Increasing fan pressure on the surface will marginally increase the effective air at the face but this will also increase air leakages. This possible solution therefore requires tightening up all sources of leakages (which should be done in any case). A more effective solution is the addition of booster fans which, while increasing total fan pressure, distributes the pressure along the circuit thereby minimizing excessive large pressure differences across ventilation doors and stopings near the surface.
In both cases, however, power costs are increased.
Controlled recirculation is one more method used to solve the problem of the long distances air must travel from the surface to the workplace and back. The concept of controlled recirculation is that a controlled portion of the air returning from the workplace is reintroduced back into the intake airways at some point underground on the return side of a booster fan. The success of this concept depends upon an acceptance of a certain level of methane in the intake air being fed to the work- place.
In order to reach the maximun level of security, the final solution was the construction of auxiliary ventilation offshore structures to solve the problem of ventilation in the mines currently in operation. There are small offshore platforms that drill the ocean floor by inserting a pipe through which air is introduced under pressure. The circuit is completed with the air being extracted by the well or main ramp. (Located on the mainland.)
However, as the distance to the coastline increases is necessary to find new solutions that provide access to the mine from the sea. Currently, Petronor Coal is finishing an "artificial island" from which they expect to access through a shaft to the coal seams located 400-900 meters below the seabed. The sea depth at this point is 74 meters. This will be the first of the next generation undersea mines. In 2010 undersea mining produced 3.8 millions metric tons of coal and it is expected to increase the production in the comming years.
Underground coal gasification
Underground coal gasification (UCG) is an industrial process, which converts coal into product gas. UCG is an in-situ gasification process carried out in non-mined coal seams using injection of oxidants and bringing the product gas to surface through production wells drilled from the surface. The product gas can be used as a chemical feedstock, as fuel for power generation. The technique can be applied to resources that are otherwise unprofitable or technically complicated to extract by traditional mining methods and it also offers an alternative to conventional coal mining methods for some resources.
Actually there are two operational underground coal gasification operations in Euskadi. The first is associated with the traditional mining operations that EHSA has in Salinas de Oro while the second one is made offshore by Petronor.
Applied to the exploitation of underwater coalbeds, this method provides an alternative for those layers that are in deep water or too far from the coast. In the continental shelf, oxidizing gases are introduced into the layers of coal from existing offshore oil platforms and the resulting gas is extracted by the same way. The gas is refined and separated in the platform so that the CO2 and other polluting gases are injected again to the reservoir. (See:Carbon capture and storage). Once the Syngas is separated it is sent to the coast by the existent pipelines. The equivalent of 1.75 billions cu m of gas were produced by this way in 2010.
As domestic production of natural gas will be increased in coming years the importance of coal as primary energy source in Euskadi will fall from current high levels. However, and looking for a balance in the energy mix, it is expected that coal will continue to supply about 35% of primary energy used in Euskadi in the mid term.