干旱区生态环境知识资源中心

World economic growth has been made possible by the ability to harness the energy of fossil fuels. From the Industrial Revolution to the present, the atmospheric concentration of carbon dioxide has increased by about 30% (IPCC in Changes in atmospheric carbon dioxide, methane and nitrous oxide. 2016), and these environmental changes have led to significant climate change effects, such as rising temperatures, water shortages, soil loss and the 'intensification of the process of desertification. Western societies are characterized by high energy consumption and, with the population growth and economic growth in emerging countries, the effects will tend to be increase more and more. Current patterns of production and consumption have proven unsustainable, and we need radical changes to escape this vicious circle affecting humanity. But, it is necessary first of all to realize that constant economic growth and the indiscriminate us of the energy sector are physically impossible on a planet of finite size and limited resources. In the encyclical, Laudato Si', Pope Francis fully embraced the message of environmental economists defining the environment as a "good that the market mechanisms are not able to defend" (paragraph 190). The Pope appears to be in tune with what has been stated by the scientific literature about the possible roads to take to resolve the problem: "the consumption of fossil fuels must decrease without delay" (165), simultaneously, "the transition from the use thereof to renewable energy sources should not be hindered, but accelerated "(26). It is necessary to adopt a circular pattern of production to ensure resources for everyone by using, in particular, renewable energy progressively, thus reducing dependency on fossil fuels. In this sense, the agricultural world, thanks to renewable resources and the adoption of advanced practices such as anaerobic digestion, could play a role of fundamental importance to an economy based on sustainable use of resources and circularity. The chain of biogas, in fact, is based on a natural biological process which, starting from the residues of agricultural activities, can produce electricity, heat or biomethane, in addition to the digestate, a byproduct of the anaerobic digestion process, which can be used in agriculture to improve soil fertility through the continuous recycling of organic substances. This paper aims to show how the creation of an anaerobic digestion plant on a farm might be the answer for the attainment of an advanced agricultural model, competitive and sustainable, both in environmental and economic-tale: the perfect example of a circular economy.