City-integrated renewable energy for urban sustainability

Abstract

To prepare for an urban influx of 2.5 billion people by 2050, it is critical to create cities that are lowcarbon, resilient, and livable. Cities not only contribute to global climate change by emitting the majority of anthropogenic greenhouse gases but also are particularly vulnerable to the effects of climate change and extreme weather. We explore options for establishing sustainable energy systems by reducing energy consumption, particularly in the buildings and transportation sectors, and providing robust, decentralized, and renewable energy sources. Through technical advancements in power density, city-integrated renewable energy will be better suited to satisfy the high-energy demands of growing urban areas. Several economic, technical, behavioral, and political challenges need to be overcome for innovation to improve urban sustainability.S ince 2007, a greater percentage of the global population has been living in urban areas than in rural areas. Increased urbanization is expected to continue, with two-thirds of the world's population projected to live in urban areas by 2050, a net urban influx of 2.5 billion people (1). Cities today are generally not equipped to address dramatic urban growth and strain on existing infrastructure in a sustainable way, especially with respect to their energy systems.To be sustainable, cities must themselves, or in the resources that they command, become lowcarbon, resilient, and livable (2). Although there can be considerable variation in methods for evaluating the emissions footprint of cities (3), with 54% of the population living in urban areas, it is estimated that cities are currently responsible for 60 to 70% of anthropogenic greenhouse gas emissions (4). The two main strategies for transitioning to a low-carbon city are to shift from fossil fuels to cleaner energy sources and to reduce urban energy consumption levels. The low-carbon transition can be accomplished through energyefficiency measures, behavioral interventions, and incorporating carbon sinks such as urban parks. Cities and their energy systems should also be resilient to natural and human-made threats (2). The energy systems of cities are increasingly vulnerable to the effects of climate change and extreme weather, including storms, flooding, and sea-level rise, and also to natural and humaninduced disasters. In addition, urban energy systems directly affect the well-being and happiness of urban inhabitants. Health conditions, economic competitiveness, cultural appeal, and social, gender, and racial equality are influenced by high-energy sectors such as transportation, food production, and water quality.Here we evaluate some of the more promising recent technological advancements that could help urban areas become sustainable cities. Many opportunities exist, but focusing on city-integrated renewable energy-defined as distributed, nonfossil fuel energy generated locally in urban areas-has the potential to help cities meet several sustainability needs. Many of these renewable sources increase regional ener...

A Dynamic Analysis to Evaluate the Environmental Performance of Cities in China

“…However, it is difficult to identify environmental factors of a city specifically because of the characteristics of system integration, multi-stakeholders, and complexity [11]. The general solution…”

City-integrated photovoltaics sustainably satisfy urban transportation energy needs

“…Not only has the installed price of solar energy dropped by as much as 50% since 2010 [4], but the power densities have increased dramatically. In the most solar-rich places in the world, using the mostefficient laboratory tested multi-junction solar cells, the power density of photovoltaics could exceed 120 W/m 2 [5]. Since the solar resource is highly varied, 87 cities from 43 countries are considered to study the feasibility of using city-integrated photovoltaics at a commercially available 15% efficiency to satisfy all urban transportation energy needs.…”

An analysis of thermodynamic properties in both traditional and enhanced geothermal systems to compare thermal efficiencies

“…These are cracks within the earth that allow for a geothermal fluid (usually water) to be injected through a rock fracture system [4]. Because of this, it is theorised that EGS's could operate with similar efficiencies at as little as half the of the temperature at which GS systems operate [3].…”

“…In the mid-20th century, many influential governments around the world including China, India and the United States began to recognise the need for an increased renewable energy infrastructure to sustain the growing demand and increased consumption of electricity [3]. Technological mining developments in drilling, allowing for extended drill depth capacity in the 1970's and progressive research into geothermal engineering processes provided a solution to overcome the restrictions and limitations of traditional geothermal systems.…”