The world's population is growing steadily. According to the United Nations, the world's population will grow to 9.7 billion people in 2050. By 2100, nearly 11 billion people could live on Earth. This rapid population growth is accompanied by an increased degree of urbanization. While around 55% of the world's population lived in urban areas in 2018, this proportion will rise to around 68% by 2050. Cities, therefore, face incredible problems such as environmental degradation and pollution, urban immobility, and increased energy demand.
Given this, cities need to look for sustainable and smart solutions to address these problems. Smart cities, sustainability, and energy are connected concepts. They have an integrated approach to promoting the sustainability and quality of life of the population.
Due to the booming population, there is also an increased demand for electrical energy. However, the solution to meeting this need is not to expand energy production from traditional fossil fuels.
With SDG 7, the UN deals with access to a wide range of energy sources – in particular to environmentally friendly, renewable, and efficient energy sources. Accordingly, energy must not only be clean, but also affordable.
Currently, cities are responsible for 67%-76% of the world's total energy consumption and 71%-76% of energy-related CO2 emissions.
To achieve the goals of the Paris Climate Agreement to become climate-neutral by 2050, greenhouse gases must be drastically reduced. This requires a strong energy infrastructure with which large quantities of renewable energy can be reliably supplied. One way to achieve this is to revolutionize energy systems so that only sustainable and renewable energy is generated.
The first step is to save energy.
Energy conversion programs, which are gradually transitioning from fossil fuels to renewable energy sources, are not enough on their own.
The necessary tool to introduce renewable energy has long been available due to the technology. The only question is how cities use the technology and how we can minimize energy consumption and energy waste.
Future possibilities of renewable energy sources in cities
To generate energy using solar energy, there are two types of conversion technologies: photovoltaics (PV) and solar panels. PV is used to generate electricity; solar panels are used to generate heat energy.
Technical solutions include PV solar systems. These are usually installed or integrated on roofs or building facades. Proximity to the consumer is the most important technical advantage of systems for residential buildings. Transport fees and energy losses are avoided in this way. However, there are also many social and environmental benefits, such as increased resilience to extreme weather events, as well as the effects of climate change.
But there are also some disadvantages. On the one hand, the restriction of the land. Cities often lack the right land to install PV systems, or the cost to the land is too high. On the other hand, the integration of VRE sources can have an impact on grid operation and impair the urban power grid and grid stability.
Wind energy has evolved in recent years. However, it has not yet penetrated the built environment. Their size, the inability to detect turbulent flows and low wind speeds, noise and controversial aesthetic, as well as an insufficient understanding of the aerodynamics of the wind, are among the biggest problems. The performance of urban wind turbines also needs to be improved. The use of wind turbines in urban areas is mainly in the research and development phase (R&D).
Bioenergy and waste-to-energy
In bioenergy, locally available raw materials are preferred from a logistical and ecological point of view. Local biomass, which is needed for energy production, can come from agricultural and forestry areas near the city, as well as from urban waste streams. The recycling of waste has another advantage – the protection of the environment through littering. Bioenergy has some advantages. On the one hand, it offers a constant and reliable energy supply, on the other hand, it is an attractive solution for the waste management of a city. In this way, the emission of greenhouse gases, as well as other environmental pollution is reduced.
However, the sustainable supply of raw materials is not always guaranteed. The supply depends on a partly limited collection radius for forestry and agricultural waste, as well as on the waste management system. In addition, it is questionable how the public feels about bioenergy because waste incineration plants can affect air quality and therefore also the health of the public. A coupling of waste management and the energy sector is needed to be able to ensure appropriate measures.
Geothermal energy plays an important role in the electricity and heating network. Geothermal energy can provide cold, heat, and electricity. For intelligent energy systems, near-surface geothermal energy is an important source of energy. Intelligent heat and power grids are connected via underground heat storage systems. In this way, an affordable and reliable heating and cooling supply can be ensured for both urban and rural areas.
Geothermal energy is used in particular for space heating and room cooling, as well as for hot water in cities. How? By using the energy obtained, which is stored in the soil or the rock below the earth.
There are 2 technologies:
- Geothermal heat water pumps: used for individual and tertiary buildings. The heat water pumps can be used in systems of different sizes and offer water heating, low-temperature cooling, and low-temperature heating. This technology is a particularly attractive solution for new near-zero energy (NZEB) buildings and for existing buildings that are being renovated.
- Borehole Thermal Energy Storage (BTES) or Aquifer Thermal Energy Storage (ATES): used for the seasonal recovery and storage of thermal energy. The energy is stored as soon as it is available and can be used when needed.
Smart grids combine generation, storage, and consumption. A central control system optimally coordinates them with each other and thus compensates for power fluctuations in the grid – particularly due to fluctuating renewable energies. A smart grid is equipped with information and communication technology (ICT). This enables real-time communication between utilities and consumers. In this way, a more dynamic interaction in the flow of energy is created, which in turn can contribute to a more sustainable and efficient power supply.
What are the benefits of smart grids?
- More efficient transmission of electricity
- Quicker restoration of electricity after power disturbances
- Reduced operations and management costs for utilities, and ultimately lower power costs for consumers
- Reduced peak demand, which will also help lower electricity rates
- Increased integration of large-scale renewable energy systems
- Better integration of customer-owner power generation systems, including renewable energy systems
- Improved security
Smart cities, therefore, have a variety of possibilities to use renewable energy sources, saving costs and minimizing greenhouse gas emissions. However, despite having many options available, there is no one-size-fits-all solution for our cities. A combination of these innovative measures and a strong commitment to the United Nations Sustainability Goals and the Paris Agreement is essential if our cities are going to be strong and resilient in the future.
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