# Biomass District Heating Systems Based on Agriculture Residues
## 1 Introduction  
One of the key factors to control global warming is to improve the energy efficiency at residential areas, one of the large energy consumption sectors. Buildings are responsible of above 40% of the total energy demand, mainly covered by fossil fuels, with the associated greenhouse gases emissions. Even though technology evolution produces more efficient energy systems, the global energy consumption is continuously increasing [1]. The improvement in the quality of energy distribution is one of the great challenges facing today's society for future decades [2]. On this goal, the replacement of existing low efficiency heating systems by high efficiency district heating and cooling (DHC) facilities based on renewable sources is of the highest interest [3]. Their implementation can generate significant fuel and cost savings, reducing significantly greenhouse gases emissions [4; 5]. On the other hand, despite their high interest, it is necessary the development of adequate regulatory and financial frameworks to support the large scale implementation of advanced district heating networks. It should also be noted that the development of new DH systems involves the displacement of existing heating technologies and it implies infrastructures development in public areas [6]. In Europe, the Energy Efficiency Directive (EDD-2012/27/EU) [7] establishes a common framework on measures to promote energy efficiency in the European Union. According to EED-2012/27, DHC cogeneration systems deployment is a promising pathway for reducing primary energy consumption. However, DHC technologies are largely untapped. One of the key points addressed in EDD-2012/27/EU is that the potential for the implementation of district heating networks should be evaluated. DHC systems will have quite different design and performance characteristics depending on their location and local resources availability. There will be different requirements to fulfil from social, legal and economic points of view depending on location that will affect to their viability and sustainability. On this sense a first general classification for DHC systems can be done in terms of the implantation area: urban, rural and industrial. Each of these types usually has common characteristics and specific requirements for viable and sustainable District Heating and Cooling systems development. Usually they have different ranges of population density, heat demand density, space availability, infrastructure development constrains, gas natural supply, local regulations development, air quality constrains, etc. Therefore, different methodologies are required in order to an adequate evaluation of their potential implantation [8]. On this purpose, previous research works have studied the potential for DHC [8; 9]. In [8], a methodology is established to evaluate the potential of a large scale implementation of Combined Heat & Power District Heating (CHP-DH) systems in urban areas with natural gas network availability. The application to the continental region of Spain results in a quite efficient of CHP-DH, simultaneous thermal and electrical generation system. In [9], a procedure is established and applied to evaluate the massive implementation of DH networks in rural areas. For this case, and focused on rural areas where there is no natural gas network for continuous supply of natural gas, biomass district heating systems (BioDH) are evaluated. The use of biomass as fuel in these areas implies the use of a resource fully integrated in their environment and with capacity for reducing greenhouse gases emissions and with potential to improve the economy of the region [10]. Depending on the location, an usual situation is that rural municipalities have not all the forest biomass resources required by the BioDH systems in their own territory [9]. So, supply from neighboring municipalities is required to achieve the required biomass supply for the development of BioDH. It involves challenges in the management of the forestry biomass resource [6].