Energy Comes Together
The Integration of All Systems
Energy systems have evolved from small, local, single technologies at single locations into highly integrated, continental-scale systems that deliver energy services to our homes and businesses. Energy systems include not only renewable, nuclear, and fossil energy sources connected to electric power networks but also other fuel infrastructures such as natural gas networks, oil pipelines, as well as thermal heating and cooling networks at a variety of different scales (Figure 1). Interactions and interdependencies are increasing among these networks and across the multiple scales of the energy system. Additionally, there are notable interactions and interdependencies between energy systems and other systems such as data and information networks, transport, and water.
Energy systems integration (ESI) enables the effective analysis, design, and control of these interactions and interdependencies along technical, economic, regulatory, and social dimensions. By focusing on these energy networks at all scales, we can better understand and make use of the cobenefits that increase reliability and performance, reduce cost, and minimize environmental impacts.
The pace of integration in our energy system is being driven by many diverse factors. Traditional economic factors, such as growing economies of scale and energy waste reduction, are driving the deployment of energy technologies such as combined heat and power (CHP) that have multiple inputs (such as gas, coal, and hydrogen) and multiple outputs (such as heat and/or electricity). These multi-input, multi-output devices can increase the resilience of the energy system, which reduces concerns over the security of energy supply. The security of supply and environmental concerns combine to drive the deployment of dispersed renewable energy resources that are typically distant from the demand centers, driving the need for better coordination of the electricity network across multiple scales and within the energy systems. For example, the decarbonization of electricity can make heat loads very attractive environmentally and economically and can be used as a form of flexibility by providing energy storage.
The relatively low carbon impact of gas, its flexibility (in terms of ramping ability) in electricity generation, and its recent increased availability is underpinning a nexus of renewables, gas, and electricity over the coming decades. This physical integration is also accompanied by a strong social and market integration with global political initiatives on climate change increasing the size and coordination of energy markets and leading to more integrated energy policies and systems.
The combination of low-cost electronic monitoring and control and the integration of data and information networks with the energy system is also enabling advanced control and coordination across the energy networks and at multiple scales. In addition, improved monitoring and control, reductions in local power production costs (e.g., from cost-competitive photovoltaics and fuel cells), interactive local energy management systems, and the potential electrification of automobiles allow consumers to play an increasingly influential role in the future of energy systems by giving them the opportunity to act as producers as well as consumers of energy and provide services to the larger energy system.
ESI is fundamentally complex to a degree that is difficult to appreciate. Core technical complexity across a range of scales and physical domains is intertwined with social, political, and economic factors. Without a holistic approach, there is significant danger that local optimizations may produce a solution that is far from optimal on a global or societal scale, e.g., the engineering solution of building more electricity transmission or new gas pipeline may be halted by local opposition.
This issue of IEEE Power & Energy Magazine came about through a growing realization among many practitioners in the energy system field that integrated solutions are emerging as the best and may be preferred to isolated solutions. This issue contains six articles, three from Europe, two from North America, and one from Asia. The authors span the disciplines of electrical engineering, mechanical engineering, civil engineering, applied mathematics, computing, economics, geography, and policy, highlighting the interdisciplinary nature of the ESI field. Throughout these articles, some of the most difficult energy challenges of our time are addressed with an integrated energy systems approach.
In the first article, Jim McCally et al. use an optimization approach to discover how best to invest in energy systems of the future to achieve desired emissions while supplying low-cost energy for electrical demand, transportation, and industrial processes in the United States. The authors address three planning issues, namely longterm investment planning strategies, new planning procedures and tools, and stakeholder processes, to facilitate decision making at a national scale. The planning process examines four innovative strategies that highlight the need for integrated energy system planning including: the development of highcapacity interregional electric transmission, the development of flex-fuel polygeneration conversion stations, the development of compressed and liquid natural gas refueling stations and associated pipeline capacity, and the development of high-speed passenger rail to connect population centers.
In the second article, John Holmes discusses the European Union’s targets and policies to establish a European energy system that is sustainable, enhances Europe’s competitiveness, and improves the security of energy supplies to its citizens. A key part of Europe’s strategies to achieve these goals is to establish a more integrated energy system for Europe in which there is a well-connected and competitive market, particularly for gas and electricity. This article summarizes the ESI issues addressed in four studies undertaken by the European Academies Science Advisory Council (EASAC) over the last four years and distills some cross-cutting conclusions on the challenges associated with the analysis, design, and operation of integrated energy systems and how they may be met. The topics include the development of an integrated European electricity network, concentrating solar power and its integration into the European electricity network, biofuels and the interface with the food system, and the possible need for a CO2 network to facilitate carbon capture and sequestration.
The third article is a detailed case study of Denmark, which arguably has the most advanced integrated energy infrastructure in the world. In this article, Peter Meibom et al. describe the current revolution in integrated energy systems in Denmark and the plans to achieve 100% renewable energy by 2050. Currently, the Danish electricity system is supplied 30% by wind energy, the highest in the world, and to reach the 100% target, the proportion of total energy in the form of electricity is expected to grow dramatically as is flexibility from demand, a key enabler. The further integration of electricity, heat with demand side, renewable-based gas, and a transport network is seen as the source of the required flexibility in the future. As with several articles in this issue, the importance of appropriate and new modeling tools and computational methods is highlighted.
The fourth article, written by Chongqing Kang et al., looks at the current integrated energy situation in China. China’s expansion of its energy infrastructure is arguably the most rapid and dramatic in the history of mankind, and the centralized approach to energy planning contrasts with the situation described by McCalley et al. in which a detailed stakeholder process is required to get consensus on energy infrastructure. The Chinese government has made significant efforts to increase the amount of renewable energy and build CHP and other required infrastructure to increase the efficiency of energy systems. However, despite the rapid development of the electricity network infrastructure, the speed of development combined with the inflexibility of the CHP and policies have resulted in difficulties in integrating variable renewable energy, in particular wind, resulting in a significant curtailment. This is in stark contrast with the Danish experience, where flexibility in CHP coupled with a functioning market and substantial interconnection has allowed the integration of wind with virtually zero curtailment. Significant further development of renewables, ultra-high voltage transmission, pumped hydro, carbon capture, and sequestration and policy evolutions are planned to meet increasing energy demand and higher levels of renewables. however, a more integrated and holistic approach is envisaged that would increase flexibility and help accommodate more variable renewable energy sources in China.
The fifth article describes work undertaken by the national renewable Energy laboratory and their colleagues at general Electric and in hawaii on the island of maui. as an island, maui is a wonderful laboratory in which to observe and test new paradigms and enhance our understanding of energy use and the potential for EsI. Currently, a large amount of wind power produced on maui is curtailed because it cannot be accommodated by the existing power network. this article analyzes changes in electrical network operations to reduce wind and anticipated solar curtailment and investigates synergies between electricity and transportation sectors to allow for higher penetrations of these variable energy resources.
Finally, the sixth article examines the integration of energy networks and the modeling of these interconnected networks at a buildings and district scale. researchers at the University of leuven in Belgium describe the advantages of EsI for electrical modeling and assessments. their work can assess the integration, interaction, control, and feedback of energy in buildings and district systems and includes the electrical network to which buildings, loads, and distributed generation units are connected. By taking into account the limitations of the electrical network, this research makes it possible to assess the impact of all the energy systems on these networks and investigate the possible interactions with the complete energy system. this article is also closest to a specialist area of EsI that is promoted by Chris marnay in his “In my view” contribution.
We believe that these six articles represent the emergence of a fundamental shift in our energy system from one where there were well-defined boundaries within the energy system and between the energy system and other systems (such as data, transport, and water) to a future where all systems are integrated. these articles underpin the concept that, by examining energy system in a holistic manner, great improvements can be made in the overall system efficiency, resilience, reliability, and environmental sustainability. We hope you enjoy diving into these articles to understand the EsI revolution that is happening around the world. the next time you consider a possible solution to an energy problem, you may want to look outside the narrow confines of one energy system and consider a solution that involves not only other energy systems but other interdependent infrastructures.