Energies 2010, 3, 462-591; doi:10.3390/en3030462 OPEN ACCESS energies ISSN 1996-1073 www.mdpi.com/journal/energies Review Current State of Development of Electricity-Generating Technologies: A Literature Review Manfred Lenzen ISA, School of Physics, A28, The University of Sydney, Sydney, NSW 2006, Australia; E-Mail: [email protected] Received: 3 February 2010 / Accepted: 10 March 2010 / Published: 18 March 2010 Abstract: Electricity is perhaps the most versatile energy carrier in modern economies, and it is therefore fundamentally linked to human and economic development. Electricity growth has outpaced that of any other fuel, leading to ever-increasing shares in the overall mix. This trend is expected to continue throughout the following decades, as large— especially rural—segments of the world population in developing countries start to climb the “energy ladder” and become connected to power grids. Electricity therefore deserves particular attention with regard to its contribution to global greenhouse gas emissions, which is reflected in the ongoing development of low-carbon technologies for power generation. The focus of this updated review of electricity-generating technologies is twofold: (a) to provide more technical information than is usually found in global assessments on critical technical aspects, such as variability of wind power, and (b) to capture the most recent findings from the international literature. This report covers eight technologies. Seven of these are generating technologies: hydro-, nuclear, wind, photovoltaic, concentrating solar, geothermal and biomass power. The remaining technology is carbon capture and storage. This selection is fairly representative for technologies that are important in terms of their potential capacity to contribute to a low- carbon world economy. Keywords: electricity generation; global status review; renewable energy; nuclear energy; carbon capture and storage Energies 2010, 3 463 1. Summary Electricity is perhaps the most versatile energy carrier in modern economies, and it is therefore fundamentally linked to human and economic development. Electricity growth has outpaced that of any other fuel, leading to ever-increasing shares in the overall mix. This trend is expected to continue throughout the following decades, as large—especially rural—segments of the world population in developing countries start climbing the “energy ladder” and become connected to power grids [1]. Electricity therefore deserves particular attention with regard to its contribution to global greenhouse gas emissions, which is reflected in the ongoing development of low-carbon technologies for power generation. Why the need for a new assessment of the state of electricity-generating technologies? This work does not aim to replace milestone reports such as the Energy Technology Perspectives [2], or the World Energy Assessment [1]. Its main focus is rather twofold: a) to provide more technical information than is usually found in global assessments on critical technical aspects, such as variability of wind power, and b) to capture the most recent findings from the international literature. As for the second aim, the large majority of a total of 361 references included in this report are more recent than 2004, the year with the most of references cited is 2008, followed by 2007 and 2009 (Figure 1). Figure 1. Frequency distribution of citations in this report across publication years. 120 100 80 citations 60 of 40 Number 20 0 2009 2008 2007 2006 2005 2004 2003 2002 2001 2000 1999 1998 1997 1996 1995 1994 1993 1992 1991 1990 1989 1988 1987 1986 1985 1984 1983 1982 1981 1980 This report was commissioned with the objective of providing an up-to-date snapshot of multiple criteria related to electricity generation, but not with the objective to provide a tool or a basis for multi-criteria decision analysis. It was acknowledged, however, that this study could provide a starting point for further investigation of that subject. Nevertheless, the following observations are made: a multitude of aspects play a role in societal debate in comparing electricity generating options, such as cost, greenhouse gas emissions, radiological and toxicological exposure, occupational health and safety, domestic energy security, employment, and social impacts. Decision-makers will in general Energies 2010, 3 464 weight these aspects differently, and similarly the literature deals with these issues in varying ways. Attempts to quantify the varied consequences of electricity generation in one end-point indicator in order to aid decision-making are fraught with problems, amongst which uncertainty and the discounting are perhaps the two most extremely challenging, despite the fact that relative rankings of electricity generation options did not change substantially during the course of the ExternE project (Figure 2 in [3]). First, on a purely scientific basis, and from a statistical point of view, in many cases the large uncertainties associated with impact and damage parameters preclude decision-making [4]. For example the very-long-term consequences of radioactive waste disposal are almost impossible to reliably predict, given the very long time horizons, and the lack of practical experience with operating repositories. Also the systematic incompleteness of impact pathways covered means that central values and ranges for damages can in principle not be stated. Second, whenever impact lifetimes are long such as global warming, long-term habitat transformation, or radioactive releases, monetary comparisons of future damages are extremely sensitive with regard to the discount rates assumed, leading to the complete failure of conventional cost-benefit analysis (for example, applying an even very small discount rate to time spans of the order of nuclear waste half lives would set the present value of future damages practically to 0). This is in addition to the difficulty of arguing an intergenerational discounting process, when the preferences of future humans are not even known (see the interesting contributions in the literature on discounting, such as [5–11]). It is hence increasingly accepted that a purely technical approach aiming at objective and unique assessment of risk is infeasible, and that risk has legitimate and important ethical dimensions that must be considered and managed [12]. A scientific-quantitative approach alone does not provide a basis for comparisons and decisions. Philosophy and lifestyles come into play in determining preferred energy strategies (Section 3.1 in [3]). Here, a whole range of criteria applies, such as spatial and temporal immediacy, ability to control or trust in decision-makers, fear and dread, knowledge and familiarity, risk profile (probability and magnitude). The formation of public perception is further complicated by the fact that media and political campaigns often comment more rapidly and decisively on contentious issues, thus reaching the public more effectively than sources of less biased factual information. For example nuclear energy is often portrayed and hence perceived as an invisible danger under the control of a few, and associated with military use, suppression of information, and high accident risk [13,14]. On the other hand of the spectrum, large hydroelectric dams are associated with the forceful resettlement of large numbers of people, and the destruction of archaeological heritage and biodiversity [15]. Similarly, but perhaps surprisingly, offshore wind power is at times strongly opposed for environmental reasons, often based on beliefs that are “stunningly at odds” with the scientific literature [16]. Whilst public acceptance must play a role in decision-making, it is important that the public forms their opinion on the basis of complete, transparent and balanced information. Unfortunately, in this respect, the literature examined in this report revealed examples of bias and omission. This report covers eight technologies. Seven of these are generating technologies: hydro-, nuclear, wind, photovoltaic, concentrating solar, geothermal and biomass power. The remaining technology is carbon capture and storage. This selection is fairly representative for technologies that are important in terms of their potential capacity to contribute to a low-carbon world economy. Currently, only nuclear and hydropower generate significant low-carbon portions of global electricity (Figure 2). Energies 2010, 3 465 Figure 2. 2006 regional and fuel split of world electricity generation (compiled from data in [17]). Other RoW hydro sources US coal RoW nuclear US oil US gas RoW gas US nuclear US hydro RoW oil RoW coal China coal Iran gas China oil Australia coal China hydro South Africa coal Italy gas India coal Brazil hydro France nuclear India hydro Sweden hydro Germany coal Sweden nuclear UK nuclear UK gas Russia Germany nuclear Canada hydro UK coal coal Japan Canada nuclear nuclear Japan coal Korea nuclear Russia Japan Japan oil gas Korea coal hydro Japan gas Russia hydro Russia nuclear This report does not cover supply-side and end-use efficiency and conservation measures, and it does not cover some future electricity-generating technologies such as fuel cells, wave, current and tidal power, and nuclear fusion, though it does provide a starting point for further study. Further, it deals with combined heat and power, and storage technologies only where they have a major bearing on the generation performance of the seven technologies listed above. Finally, it does not deal