1.1 Introduction
The industrial growth and the increasing desire of growing population to improve quality of life have led to the increasing demand on energy. Energy is extremely important for any economy to generate wealth and it is the key component for GDP growth. It is estimated to grow from 549 quadrillion British thermal units (Btu) in 2012 to 815 quadrillion Btu in 2040, 48% increase in 28 years. The energy demand could have more than doubled without efficiency gain and suitable energy mix. The non-Organization for Economic Cooperation and Development (non-OECD) countries are the major contributor in this drastic energy demand. In these countries, energy demand will rise by 71% from 2012 to 2040 in contrast with only 18% in developed countries in same time span. An average GDP growth of 4.2% per year is estimated between 2012 and 2014 in non-OECD countries as compared to 2.0% per year in OECD countries as estimated by IEO2016. In terms of energy consumption by sectors, industry is leading followed by residential and transport. This trend persists from 1971 to 2014, and overall industrial consumption doubled during this period. Power plant sectors consume 35% of global energy, and it is estimated to grow due to urbanization in developing countries. Global electricity demand is expected to increase over 65% from 2014 to 2040, 2.5 times faster than overall energy demand [1,2].
The competition among countries for the industrial development has severe impact on the environment in terms of CO2 emission. Every drop of fuel pollutes environment and intensity depends on process efficiency. Global CO2 emission measured as 40 gigaton (Gt) per year in 2016 is almost double as compared to 1980 emission level. Energy sector is the major contributor, 68%, in CO2 emission and power generation sector sharing 42% in energy sector emission followed by transport 23% and industry 19%. A systematic diversification of the global energy mix and technology improvement driven by economics and climate policies almost flattens the CO2 emission rate in 2014, only 0.8% increase, as compared to 1.7% in 2013 and 3.5% in 2000. During 2012–2014, the moderate increase in CO2 emission, 0.8%–1.7%, is remarkable when global economic growth rate was 3% as compared to 4% emission annually with GDP growth rate of 4.5% in last decade. In other words, partial decoupling of economic growth and CO2 emission has been observed in 2012–2014 due to shift in energy production and consumption, power generation, technological improvements, and policy implementation. In 2015, the milestone year, 170 countries signed an agreement at the 21st Conference of the Parties (COP21) in Paris for climate action. The Paris Agreement is the first international climate agreement extending mitigation obligations to all developed and developing countries representing over 90% of energy-related CO2 emissions and approximately 7 billion people. The agreement aims to achieve CO2 emission peak as soon as possible to cap the increase in the global average temperature to below 2°C. In addition, it also aims to pursue extra efforts to limit the temperature increase to 1.5°C. Business as usual scenario, as most of the countries followed, can lead to over 5°C temperature increase [1,2].
Going forward, along with reduction in carbon emission, affordable cost, commercial viability of technology, and equal access of energy by both urban and rural communities are important drivers for the energy industry. There has been a recognition by the energy industry in recent years that there are ten sources of energy in the world: coal, oil, gas, biomass, waste, nuclear, solar, wind, geothermal, and water. As pointed out in my previous book [3] that none of these sources satisfies completely all the requirements of energy production. Their availability also varies significantly across the world. In order to capture renewable source, particularly non-dispatchable sources like solar and wind, energy storage has become very important. In the past hydropower storage captured about 95% of storage market although at smaller scale, batteries have captured the most attention. Just like multiplicity of energy sources, there are also multiple types of storage devices; like batteries (both non-flow and flow), capacitors (including super capacitors), mechanical storage devices like compressed air and flywheel, magnetic storage device like SMES, thermal storage like, molten salt, ice bricks, phase change materials, thermochemical heat, etc., bulk gravitational storage devices which include technologies such as pumped hydro and gravel in railcars and hydrogen storage. As shown in my previous book [3] that none of these storage devices individually meets all the requirements of the storage needs [3].
In the past, electricity was mainly supplied by macro level utility grids with power generated from centralized large-scale fossil fuel (coal or natural gas) or nuclear energy power plants. These large-scale power plants follow the economy of scale and did not require additional storage devices due to their spinning and nonspinning reserves. While they served well-urban communities, they did not serve rural and isolated communities where utility grid was not accessible. In recent years, the desired access of renewable sources changed this paradigm. Unlike large-scale fossil fuel and nuclear-based power plants, renewable sources are of low density and more distributed. In order to capture these distributed generation sources, a new grid structure, microgrids, is developed which can be connected to utility grid or can operate in islanded mode at medium-to-low voltages more near customers. Furthermore, in order to serve rural and isolated communities, off-grid structures of minigrids, nanogrids, and stand-alone systems are developed which are not connected to the utility grid. These different grid structures are also outlined in my previous book [3]. Thus, just like sources of generation and nature of storage, grid structure has also become hybrid in order to capture distributed renewable energy sources and serve the rural communities.
In recent years, energy industry has been going through major changes. It needs to address issues such as (a) carbon dioxide emission reduction, (b) more balanced use of all energy sources, (c) affordability for all customers, (d) accessible to both urban and rural or isolated communities, (e) more efficient in generation, storage, and distribution, and (f) more balanced between distributed and centralized mode of operation. Rapid development of new nanotechnologies makes industry to be more flexible and adaptable. These desired changes also force industry to operate in more modular form.
The pressure on energy industry to reduce carbon dioxide emission has resulted in the adoption of multiple strategies which all lead to lesser and more efficient use of fossil fuels and more insertion of renewable sources in the overall energy use mix. Low efficiency of large-scale power generation processes by coal, gas, and nuclear energy has forced to use hybrid energy systems like cogeneration or combined heat and power (CHP) to improve their efficiency. Cogeneration and CHP processes are, however, more easily implementable at smaller scale. This has also led to the development of small modular nuclear reactors.
Energy industry has recognized that the best way to respond to the required changes is to make generation, storage, and transport processes more heterogeneous. The insertion of renewable sources in hybrid grid structure is an evolving process and will require power and heating and cooling requirements to be satisfied by multiple generation sources. The evolving storage requirements will also have to be heterogeneous in order to satisfy the needs of a variety of applications such as electric car, portable electronics, hybrid grid structure, etc. The development of stable and workable off-grid structure will require significant use of multiple renewable sources which include one or more energy storage devices. Even if in long term renewable sources completely replace fossil fuels, their use will require backup devices like storage or diesel fuel. More hybrid energy systems will be required to make many systems more efficient. Thus, the energy system will become hybrid in one or other form. It appears that hybrid energy systems are the important parts of the future energy industry.
In recent years, significant efforts are made in the development of fuel cells. They are being made more affordable and durable at both large and small scales and for both static and mobile applications. Fuel cell can be either power generating or storage device. While this carbon-free device has a strong future, it also has low power density and some other limitations and will generally operate best in a hybrid form which includes another source of generation or storage. The successful development and use of fuel cells will also help decarbonize energy industry.
Going forward, energy industry has adopted following strategies to serve its needs in an environmentally acceptable way:
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Improve efficiency of all energy conversion processes. In particular, for conversion of thermal energy to electrical energy by converting waste heat to other power, fuel, or heating/cooling needs (CHP or cogeneration approach) by unique hybrid energy systems; in this regard, small modular nuclear reactors will find unique place in the future overall energy mix. Waste heat is also very prominent in industrial processes and in mobile industry.
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Reduce the use of fossil fuel by combining its usage with other forms of low carbon nuclear and renewable technologies for power and heating and cooling needs.
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Replace fossil fuels by biofuels for the production of raw materials for various chemicals, materials, fuels, and fuel additives.
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Replace fossil fuels with multiple sources of renewable energy particularly in rural and isolated off-grid communities.
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Insert renewable energy sources in utility power plants and utility grid.
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Make more efforts to harness distribute energy sources using microgrid platform.
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Make use of hybrid energy storage systems to improve efficiency of energy use in various applications.
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Convert CO2 to chemicals, materials or fuels by additional hybrid chemical or biological processes. This subject is discussed in great details in an excellent national academy of engineering report by national academy of science, engineering, and medicine [4]. This is also the theme of my next book on treatment strategies for carbon emissions.
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Make more use of hydrogen (carbon-free) base technologies.
In my previous book on hybrid power-generation, storage, and grids, the importance of hybrid energy, hybrid storage systems, and hybrid grids for power industry was delineated in detail. The book showed that for growing power industry the hybrid power is the future and it offers many positive values toward decarbonization of power industry. The book pointed out that no single source of energy satisfies all the criteria for sustainable energy. The book also pointed out that no energy storage device alone provides all the required characteristics of energy storage, such as energy density, power density, cycle life, etc. Present utility grids are not effective for harnessing distributed energy sources and they are not accessible in the rural and remote areas. Thus sources, storage devices, and grid transport all need to be hybrid and multifaceted to serve the future needs of electric power. The criteria for sustainable energy including (a) reliability and flexibility, (b) affordability, (c) accessibility, (d) high efficiency, and (e) durability and long-term sustainability are all best satisfied by the hybrid power.
In the present book, we extend the applications of the concept of hybrid energy systems to ten major industries: coal, oil and gas, nuclear, building, vehicle, manufacturing industry, computing and portable electronic industry, district heating and cooling industry, water industry and hydrogen production, and illustrate that the concept of hybrid energy systems also helps decarbonize these industries. The book illustrates various methods used to apply hybrid energy systems in these industries. For each industry, the use of power and heating and cooling needs is considered.
