Multi-Criteria Decision-Making Methods for Biomass Energy Systems: A Review

Introduction

Industrialization and motorization are increasing all over the world. Energy demand is increasing in proportion to these developments, and 80% of this need is met from fossil fuels. Despite the rapidly increasing energy demand, the effort to meet these demands with limited fossil fuels has accelerated the searching to introduce new energy sources in the coming years. One of the main motivations in these studies is that the environmental damage caused by fossil fuels is becoming challenging to reverse. Increasing energy consumption causes an increase in GHG emissions; therefore, environmental damage increases. In order to meet the energy demand in the coming years, the world has accelerated the search for environmentally friendly, renewable, efficient, and cost-effective alternative energy sources instead of fossil fuels, which are gradually decreasing and causing an increase in GHG emissions. While countries are creating their energy policies, they are taking initiatives to supply their energy demands from cheap, reliable, and sustainable alternative sources. Alternative energy is a concept that expresses the substitution of other energy sources for the need for crude oil and thus reducing the environmental damage brought about by climate change. Alternative energy sources include solar, wind, geothermal, and biomass energy. When considering renewable energy sources, solar and wind energies are the first ones that come to mind. However, from the first human to this day, many people have used wood, fertilizer, and coal as fuel while fulfilling their daily routines such as cooking. Considering the increasing population, mostly living in rural areas, especially in developing countries, the use of these resources is undeniable.

Fuelwood consumption has increased by 250% since 1960. This fact shows us that this energy, which we call biomass, is an important element of renewable energy sources. Today, biomass energy has a share of 14% in primary energy sources. Every year, several million tons of agricultural waste are destroyed in different ways, such as incineration, land applications, and landfilling. As a result, high potential bio-renewable energy sources cannot be used. Biomass energy meets 35% of the energy needs of developing countries. It is predicted that by 2050, 90% of the world population will live in developing countries. Therefore, biomass energy is of great importance for these countries where agriculture is an important source of livelihood (Pathak, Chaudhari, & Fulekar, 2013).

The world population continues to increase rapidly. Today’s world population is twice that of 1960 and is expected to approach 9 billion by 2050 (Perea-Moreno, Samerón-Manzano, & Perea-Moreno, 2019). The increase in the world population brings an increase in energy demand. Studies show that this increase in energy need has an annual acceleration of 2% (Zahid, Tahir, Khan, & Naeem, 2021). Developing countries account for 99% of this population growth, and this increase is observed as 50% in urban areas. While the share of global energy in cities was less than half of the energy produced in 1990, today, this rate constitutes two-thirds of the total energy. Fossil fuels are still used as the primary energy source in cities, and they constitute 70% of CO2 emissions, which is one of the causes of global warming. Air pollution in urban areas reaches significant levels. According to the World Health Organization (WHO), 90% of those living in urban areas are exposed to levels of environmental pollution that exceed recommended limits. 90% of all urban areas are located on the coastline. Rising sea levels make some cities vulnerable to danger in developing countries. (Perea-Moreno et al., 2019)