Sustainability

Clean technologies for coal

To achieve a less polluting use of this energy resource, over the last years technologies were developed leading to a reduction of the environmental impact in all the stages of the coal production cycle: from extraction to processing and combustion.
These technologies reduce emissions, waste, and increase the quantity of energy that can be obtained from a ton of coal. Clean technologies today allow to reduce CO2  emissions by more than 30% per unit of electric energy produced.
For example, the “fluid bed” combustion consists of burning coal together with a mixture of salts absorbing part of the ashes and toxic gases. Thus, a smaller quantity of polluting gases is freed into the atmosphere (nitrogen oxides, sulphur oxides, carbon dioxide). 
Similar results can be achieved through underground gasification processes envisaging the injection of air and steam into the coalfields until their partial combustion is achieved. Thus, only a mixture of fuel gases with no ashes reaches the surface and is then injected into traditional pipelines.
There are also some hybrid systems that combine the best characteristics of gasification and combustion technologies, using coal in a two-phase process. The first phase consists of the gasification of most of the coal that produces steam and drives it to a turbine. The second phase is the combustion of coal residues to produce steam. With technique it is possible to reach an efficiency increase by 50%.
Moreover the co-firing can be applied to any generation system. It consists of burning biomass and waste together with coal. The advantages of this technique may include the reduction of CO2, SOX,  NOX   emissions that are produced in coal traditional plants. Moreover in this way it is possible to obtain a large energy efficiency from biomass and waste, without having to build new specific plants.
From coal gasification it is possible to obtain hydrogen, which can be used to produce energy (for example in fuels cells) at “zero emissions”.