Materials for Sustainable Energy Applications

Conversion, Storage, Transmission, and Consumption

David Munoz-Rojas, Xavier Moya

• Verlag: Jenny Stanford Publishing
• Jahr: 2017
• ISBN:
  9781315341316
• Auflage: 1
• Thema: Physical Sciences
• Thema: Organic Chemistry

The impending energy crisis brought on by the running out of finite and non-homogenously distributed fossil fuel reserves and the worldwide increase in energy demand has prompted vast research in the development of sustainable energy technologies in the last few decades. However, the efficiency of most of these new technologies is relatively small and therefore it needs to be increased to eventually replace conventional technologies based on fossil fuels. The required efficiency increase primarily relies on the ability to improve the performance of the functional materials which are at the heart of these technologies. The purpose of this book is to give a unified and comprehensive presentation of the fundamentals and the use and design of novel materials for efficient sustainable energy applications, such as conversion, storage, transmission, and consumption. The book presents general coverage of the use and design of advanced materials for sustainable energy applications. Thus, the book addresses all the relevant aspects, such as materials for energy conversion, storage, transmission, and consumption.

PART 1

INTRODUCTION

Chapter 1

Energy in Transition

Pedro Gómez-Romero^a and David Muñoz-Rojas^b

^aCatalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology, Campus UAB, Bellaterra, 08193 Barcelona, Spain

^bLaboratoire des Matériaux et du Génie Physique (LMGP), University Grenoble-Alpes, CNRS, F-3800 Grenoble, France

[email protected]

An introductory chapter is a good way to start a technical book. It provides a broad overview of the field, announces the general intention of the authors, describes the structure of the book, and outlines its contents. It should not be taken, however, as a mere summary or a highlight instrument—after all this is certainly not an executive summary. Instead, we believe this introduction could go beyond the conventional goals mentioned above and provide also an account of the reasons why it is worth working on energy materials, a vision of how research and development can contribute to the due re-evolution towards a sustainable model of generation, storage, distribution, management and consumption of energy and a hint of what are the major scientific, technical and social challenges ahead.

1.1 Introduction

On Wednesday December 5, 2012, at a press conference during the Fall Meeting of the American Geophysical Union in San Francisco, NASA and NOAA scientists unveiled the latest of a series of satellite views of Earth at night. The spectacular composite photograph was assembled from cloud-free shots acquired by the visible infrared imaging radiometer suite (VIIRS) installed at the Suomi NPP satellite. The VIIRS detects light in a range of wavelengths from green to near-infrared and uses filtering techniques to observe dim signals such as city lights, gas flares, auroras, wildfires or even reflected moonlight and is sensitive enough to detect the light from a single ship in the sea. This image is already a global icon, as it was the first “Earth at Night” released in 2004 and the daylight images that conform the Blue Marble project [1].

Figure 1.1 NASA-NOAA composite view of Earth at Night, 2012.

A mere glimpse at this image immediately conveys its many wonders. Our global nature, the asymmetry of our world, the tiny light from our own hometown, the cradle of civilizations like the Nile river, the darkness of human-free sanctuaries are sensed right away. But the most striking feature, in contrast with the daylight view of Earth, is the human footprint in the form of man-made lights.

It is not language, nor the use of tools, nor the social nature of our species. What makes us different from any other living species on Earth is our use of energy. We are the only ones making use of exosomatic energy, namely, that used to sustain activities external to our own biological metabolism. In our modern technological society this social energy has been estimated to be two orders of magnitude larger than the somatic energy necessary to keep our bodies alive. That means a consumption of ca. 200,000 Kilocalories per person and day [2].

A decade and a half ago, when the world was mesmerized by the Y2K Millennium bug, most of our global exosomatic energy was extracted from fossil fuels. Coal, oil, and natural gas accounted for a total 80–85% of it, a figure that fluctuates a bit depending on whether and how the biomass used by Third World countries is accounted for. Fifteen years later, Information and Communication Technologies have evolved so wildly that our forgotten fear to a mere change of formatting dates might seem childish. However, not much has changed concerning our sources of energy. Our fossil fuel share is still 80–85% depending on estimates of biomass consumption in the Third World, and coal consumption has even grown.

Figure 1.2 shows this distribution and the trend during a period of 10 years by including percent values for years 2012 and 2002. It is interesting to note that the share of each fossil fuel changed significantly in that decade, both concerning total primary energy and electricity generation, but in both cases the overall fossil fuels share remained practically unchanged.

The development of emerging countries, in particular China, is frequently claimed as one key factor contributing to our present situation and to the forecasting of ever-growing global energy consumption in years to come. Unfair as it is to blame a country with lower consumption of energy per capita than ours, the fact is that China stands as the first producer of coal in the world, accounting for almost half of the world production (and yet, still a net importer) [3]. This supports the claims that China has based its recent growth on burning coal and has boosted global fossil fuels consumption. But China is not the only culprit in our global energy status quo. The First World overconsumption model is at the heart of the present situation, with archaic sun in the form of fossil fuels feeding our wasteful society. Indeed, the initial perception of an advanced technological world that comes with the view of Earth at night in Fig. 1.1 quickly vanishes when we realize that the overall efficiency of making those shiny technological flares is just a single-digit figure close to 5%.

Figure 1.2 Left: world total primary energy supply in 2012. Distribution by sources (%). Right: world electricity in 2012 by sources. Figures in parentheses indicate the same values, from the same source for year 2002, for comparison (data from International Energy Agency (IEA), Key World Energy Statistics, 2014) [3]. It should be noted that in these graphs, peat and oil shale are aggregated with coal.

How have we come to develop such a wasteful technosphere is not easy to understand, but at the risk of oversimplifying we could mention a couple of technological revolutions which contributed significantly to massive energy consumption. The first came about with the conjunction of the Great Britain, coal, the Steam Machine and the railroad in the XIX century. The second one was boosted by the USA, oil, the internal combustion engine and roads during the XX century. Cheap energy was at the heart of both. Cheap energy that—now we know—comes with hidden (a.k.a. non-internalized) but very high environmental, social, and public health costs.

Our energy model is bound to change. As a matter of fact, it is already gradually changing, towards a new sustainable model that will change the way we generate but also the way we distribute, store, manage, and use energy. This categorical assertion is not only based on the growing evidence for our contribution to global warming but also on the self-evident fact that any non-renewable resource will get eventually depleted if its consumption is not phased-out. Oil, for instance, will be the first fossil we will stop burning, leading our cars to quit smoking and allowing our lungs to breathe cleaner air. The future of oil as a fuel is very clear; it will be P.O. (Phase Out) or P.O. (Peak Oil). Therefore, the question is not whether we will quit burning fossils as our predominant way to get energy but when will we.

Certain energy analysts with shortsighted vision and/or with vested interests have celebrated the advent of non-conventional oil and gas as a new era in which miracles like the USA becoming a net exporter of oil could take place. But let us be clear, the very fact that the same multinational companies that have exploited easy-to-get oil during the last century are now bothering to invest heavily in oceanic deep-water prospections and in fracking (at the expense of higher oil prices and higher environmental costs) is the proof that the fossil fuel era (in particular oil) is approaching its end.

The time has come, therefore, to set the basis for the transition to a sustainable energy model. A transition that will not take place instantly or automatically. A gradual transition that nonetheless will require of proactive actors, including citizens and entrepreneurs, scientists and engineers, financial and industrial corporations and, of course, last but not least, policy makers.

Governmental support to new or strategically important technologies is not new. Whether in the form of legislation or direct subsidies every heavy industrial sector has benefitted from very generous public help, from coal to nuclear, from electrification to the car industry. Why the big fuzz then concerning the subsidies to renewables or legislation penalizing CO₂ emissions?

Damage to the economy is frequently argued as a factor against CO₂ penalties, from fossil fuels burning to concrete manufacturing. However, this primary and simplistic accounting approach has been demolished by more rigorous analyses by economists like Stern [4]. Indeed, one of the main conclusions of the Stern review is that the overall costs of climate change will be equivalent to losing between 5% and 20% of the global gross domestic product (GDP) each year, now and forever. When compared with the 1–2% of the global GDP per year that would need to be invested to avoid the worst effects of climate change, it becomes clear that the benefits of strong, early action on climate change would outweigh the dreadful future costs. But even if we stay in the realm of economic and strategic orthodoxy there are very strong arguments in favor of an ordered shift towards low-carbon and renewable technologies. These will reduce the heavy burden of non- internalized costs, derived from our way to produce energy but accounted for in other spreadsheets: health problems derived from smoking cars, cleaning costs of environmental pollution, from black tides to nuclear, or oil-war costs. Renewables will also definitively reduce our energy supply dependency from producers based on unstable territories. Renewable industries and new manufacturing players closing the circle or circular economy in all industrial sectors will be the main actors of a much-needed new productive economy. Finally, early re-evolution towards sustainability will give a competitive advantage to the societies collectively adapting themselves to the inexorably forthcoming sustainable model. Note that we have written societies, not industries or corporations. This is so because the energy conundrum is so complex and tightly intertwined with our ways of life that only an integral and collective change will suffice.

Energy, Environment and Economy are three threaded E-word concepts strongly intertwined, which can push and pull each other in complex feedback cycles (Fig. 1.3). They can configure a vicious circle of wasteful overconsumption as witnessed during the 20th century. But they can also converge into a virtuous feedback circle leading to environmental, social and economic sustainability as it will become increasingly apparent in the 21st century.

Figure 1.3 The three threaded E’s.

What primary energy will be feeding this virtuous feedback cycle in our present century is no secret. As a matter of fact, it will be primarily the same that led to our successive industrial revolutions in the 19th and 20th centuries: solar energy, of course. Except that instead of using million-year-old canned solar energy in the form of coal, oil or natural gas, we will eventually be just using contemporary solar energy. Directly or in the form of biomass, hydropower, and wind power, solar energy will dominate over non-solar (geothermal and nuclear) (See Fig. 1.4).

Figure 1.4 Graphical comparison of the current annual energy consumption of the world to (1) the known reserves of the finite fossil and nuclear resources and (2) to the yearly potential of the renewable alternatives. The volume of each sphere represents the total amount of energy recoverable from the finite reserves and the energy recoverable per year from renewable sources. Solar energy received by emerged continents only, assuming 65% losses by atmosphere and clouds. From reference [5].

The technologies for harnessing solar power are very diverse. Some have reached a maturity level that makes them stand very close to direct economic viability even without subsidies. That is the case of Thermal-solar electricity plants for instance. Other technologies are nonetheless in its infancy, like solar-driven photocatalytic reduction of CO₂. All of them will contribute to take advantage of the massive prevalence of solar energy on our blue planet.

Indeed, the solar system depicted in Fig. 1.4 is actually a graphical account of the energy available from the Sun (every year for the next 5000 million years) in comparison with estimated finite total reserves of various “primary” sources. It also depicts the annual global energy consumption by humans, presently standing at 16 TW· year and expected (by linear extrapolation) to reach 28 TW· year by 2050. The energy granted by our yearly solar bath, even after atmospheric filtering, is three orders of magnitude larger than our yearly energy needs and two orders of magnitude larger than that available from the total of estimated oil reserves. No matter how far off the latter could be, the energy we could ever get from all fossil fuels will never be comparable to the free energy provided by the sun every year.

With all this in mind, it is not difficult to forecast that solar energy, in all its forms, will have to be massively developed in order to cover our energy needs in a coming world of shrinking fossil power. Conversion of solar radiative power into electrical, chemical (and biochemical) or thermal energy will have to be mastered before we could abandon our fondness for cheap-n-wastefull energy “generation” methods.

But in addition to primary sources, we will have to worry about the setting up of a new mo...