Exploring bioenergy potentials of built-up areas based on NEG-EROEI indicators

Abstract

The production of bioenergy is dependent on the supply of biomass. Biomass production for bioenergy may cause large land use conversions, impact agricultural production, food prices, forest conservation, etc. The best solution is to use biomass that does not have agricultural or ecological value. Some of such unconventional sources of biomass are found within urban spaces. We employed Geographic Information System (GIS) and quantitative Life Cycle Assessment (LCA) methodologies to identify and estimate bioenergy potential of green roofs and other bioenergy options within urban areas. Net Energy Gain (NEG) and Energy Return on Energy Invested (EROEI) were used as indicators to assess the bioenergy potential of urban spaces within the Overijssel province of the Netherlands as a case study. Data regarding suitable areas were geometrically extracted from available GIS datasets, and used to estimate the biomass/bioenergy potential of different species with different yields per hectare, growing under different environmental conditions. We found that potential net-energy gain from built-up areas can meet 0.6-7.7% of the 2030 renewable energy targets of the province without conflicting with socio-ecological concerns, while also improving human habitat.

The Role of Renewable Energy in the Promotion of Circular Urban Metabolism

“…The development represents between 0.6% and 7.7% of the regional objectives for 2030. However, in this case, the production is not environmentally sustainable, since the relationship of input/output of energy is not efficient [52]. Even so, this author considers that this condition could be reversed in developing countries that require less demand for energy.…”

“…The residual biomass obtained from the operation of urban pruning can be used in industrial applications for the production of steam, power generation or transport [65,81]. Biomass for energy may cause severe environmental damage or impact on the provision of food, while biomass coming from urban area waste is an alternative, because urban waste would have less ecological value or agricultural importance [52]. The maintenance of gardens provides an added value to this activity, because debris can be used for energy purposes [60].…”

“…It is not clear what the best option is from the technological, social, environmental or economic point of view. The choice also depends on the available resources, on intended benefits or the decrease of externalities [51,52]. Eicker et al [53], for example, consider that photovoltaic solar energy has a greater possibility to supply urban areas, while biomass, wind or hydroelectric power outside the city can supplement the demand.…”

“…Arodudu et al [52] calculates the energy potential of biomass from rooftops, parks, waste from gardens or food and seasonal leaf drop in the region of Overijssel (The Netherlands). The exploitation is based on anaerobic digestion for biogas production.…”

Integrated ecological indicators for sustainable urban ecosystem evaluation and management

“…A general energy accounting scheme and its derived set of indicators is then analyzed to examine the basic assumptions and energy transformation process using the flow-fund representation originally developed by Georgescu-Roegen. Arodudu et al (2014) combine GIS with life cycle assessment methodologies to identify and estimate bioenergy potential of green roofs and other bioenergy options within urban areas. Net Energy Gain (NEG) and Energy Return on Energy Invested (EROEI) are used as thermodynamic indicators to assess the sustainability of bioenergy sources within urban built-up spaces by comparing their energy efficiencies and their contributions to set renewable energy targets in one frame.…”