The energy future and the role of renewable energy

Figure 1.16 shows a very large difference between the energy use of the leading countries or leading persons within countries, as compared with the least energy-using inhabitants of poor countries. This feature is currently changing, as the level of global interaction increases and every world citizen becomes aware of the kind of lifestyle that is "possible". However, the current development does not seem to indicate a diminishing ratio of the energy use of those using most and those using least energy. This is also true of other commodities related to living standard.

Energy use and resource depletion does not, of course, constitute the primary goals of any society or individual within a society. For example, average Europeans or Japanese use about half as much energy as the average North American, but have a living standard, which certainly is not lower than that of the North American citizens. This underlines the fact that the living standard and welfare depends on having primary (food, shelter, relations) as well as secondary standards of individual preference fulfilled and that this can be done in different ways with different implications for energy use.

The relationship between economic activities and social welfare has been debated for a considerable period of time, as has the possibility of physical limits to growth in material exploitation of the resources of a finite planet. The answer of conventional economists to this is that the inventiveness of man will lead to substitution of the materials threatened by exhaustion with others, in an ever-ongoing process. Recognising the finiteness of fossil and nuclear energy sources, this leads to the general prediction that renewable energy sources must take over at some stage, and the only debate is on how soon this will happen.

Most current geologists believe that oil and natural gas production will peak sometime in the next two decades. After that prices are bound to rise, thereby easing the introduction of alternative energy sources. Accepting a higher price of energy, it is also implied that energy must be used more efficiently, in order to prevent the belief that the higher energy cost slows down the development of human welfare.

This development in energy use is linked to another problem that may serve to accelerate the energy transition, namely, the increased awareness of the negative implications of environmental impacts of energy production and use. Early man was capable of causing environmental disturbance only on a very local scale. However, extensive burning of forests, for example, to provide land for agriculture, which would later be abandoned when overexploitation diminished the crop or grazing yields, may have been instrumental in creating the desert and semi-desert regions presently found at low latitudes (Bryson, 1971). This is already an important example of a possibly man-made climatic change. Recently, man has reached a technological level enabling him to convert energy at rates which can be maintained over extended areas and which are no longer small compared to the energy fluxes of solar origin that are responsible for the climate.

The average heat flux of anthropogenic origin (i.e. from fossil fuels) in an industrial and urban area such as the Los Angeles Basin (about 1010 m2) was estimated in 1970 to be 7 Wm-2 (Lees, 1970). The global average value around 1970 was 0.015 Wm-2 (see section 2.4.1), and the average solar flux absorbed by the Earth-atmosphere system is 240 Wm-2 (see Fig. 2.86). For comparison, a forest fire, which would burn down an area of fertile, tropical forests in one week, would release a heat flux of about 1000 Wm-2. Yet the average heat flux from forest fires in all continental regions, the average being over several years, is less than the average anthropogenic heat flux. The nuclear weapons arsenal built up during the last 50 years is somewhere in the range of 104-105 megatons (Feld, 1976), with the higher figure corresponding to about 4.4 x 1020 J. If these weapons were detonated within a 24-hour interval, the average energy flux would be 5 x 1015 W, and if the target area were 1012 m2, the average heat flux would be 5000 Wm-2. The destructive effects would not be confined to those related to the immediate energy release. Radioactive contamination of the environment would cause additional death and decay, and would establish further mechanisms for climatic disturbance (e.g. destruction of the stratospheric ozone shield), in addition to the difficulty presented to human survival as the dominant species on our planet.

It has been suggested that fusion energy constitutes an alternative to renewable energy as the long-term solution. However, as elaborated in section 3.7.3, it is not clear at present whether fusion energy on Earth will ever be come a feasible and practical source of controlled energy supply. It will create nuclear waste in amounts similar to those of fission technologies and will counteract the development towards decentralised technologies characterising the present trend. It is probably an exaggeration to imagine that the introduction of one kind of energy technology rather than another will determine or solve such institutional problems. What may be true, though, is that certain types of technology are more suitable for societies organised in a particular way and that the kind of technology imagined in connection with the use of certain renewable energy resources fits well both with the needs of sophisticated, decentralised societies based upon information technology and with the needs of the presently underprivileged regions.

Science and technology literature contains a range of suggestions for handling future energy demands. In the past, some of the technologies thus brought forward as "technically feasible" have actually been developed to commercial viability, and others not, for a variety of reasons. Renewable energy has over the last decades passed from the level of technical feasibility to a level of cautious introduction into the marketplace and not least into long-term government planning. One reason for the slow penetration is that some influential funding institutions, including the European Commission, have continued to use a large fraction of their R&D funds, as well as loan and aid money, on fission and fusion, ignoring the unattractiveness of the long-range radioactive waste problems and hoping to obtain short-term industry advantages in export of outdated fission technology to former East-block and developing nations. If funds were wholeheartedly aimed at a rapid transition from the fossil to the renewable era, the progress could be much faster. This has been demonstrated by a number of recent scenario studies, some of which will be described in Chapter 6. The general question of who controls technology development has been discussed by Elliott and Elliott (1976) and by Serensen (1983; 2001a). During recent decades, a number of "grassroot" movements have advocated use of renewable energy, and it can be hoped that these preferences are preserved as that generation of people make their way into decision-making positions.

Renewable energy sources are typically characterised by a theoretical maximum rate at which energy may be extracted in a "renewable" mode, i.e. the rate at which new energy is arriving or flowing into the reservoirs associated with many of the renewable energy flows. In some cases, the additional loop on a given renewable energy cycle, caused by man's utilisation of the source, will by itself modify the rate at which new energy is arriving (for instance, utilisation of temperature differences in the oceans may alter surface evaporation rates and the velocities of ocean currents; in both cases the mechanisms for establishing the temperature differences may become altered, cf. section 3.5.1). The geothermal energy flux from the interior of the Earth is not a renewable resource, since the main part of the flux is associated with a cooling of the interior (cf. section 3.5.2). On the other hand, it is a very small fraction of the heat which is lost per year (2.4 x 10-10), so for practical purposes geothermal energy behaves as a renewable resource. Only in case of overexploitation, which has characterised some geothermal steam projects, renewability is not ensured.

In Chapter 2, the nature and origin of renewable energy sources are discussed in what may resemble an odyssey through the sciences of astrophysics, atmospheric physics and chemistry, oceanography and geophysics. The importance of connecting all the pieces into an interlocking, overall picture becomes evident when the possible environmental impact of extended use of the renewable energy sources in the service of mankind is investigated in Chapter 7.

Chapter 3 provides, for each renewable energy source, an estimate of the size of the resource, defined as the maximum rate of energy extraction, which on an annual average basis will become renewed, independently of whether it is possible to extract such energy by known devices. Also issues of power density and variability are discussed in this Chapter.

Chapter 4 opens with some general features of energy conversion devices and then describes a number of examples of energy conversion equipment suitable for specific renewable energy sources.

Chapter 5 gives an overview of various methods of energy transport and storage, which, together with the energy conversion devices, will form the ingredients for total energy supply systems discussed in Chapter 6.

Chapter 6 discusses the modelling of the performance of individual renewable energy devices as well as whole systems and finally scenarios for the global use of renewable energy, with consideration of both spatial and temporal constraints in matching demand and supply.

In Chapter 7, renewable energy resources are first placed in the framework of current economic thinking, as a preliminary effort to quantify some of the considerations which should be made in constructing a viable energy supply system. Then follows a survey of indirect economic factors to consider, which leads to the description of the methodology of life-cycle analysis, which together with the scenario technique constitutes the package for an up-to-date economic analysis. It is then used in concrete examples, as a tool for systems assessment.

Chapter 8 offers some concluding remarks, notably on the renewable energy research and development areas most important for the near future.

Getting Started With Solar

Getting Started With Solar

Do we really want the one thing that gives us its resources unconditionally to suffer even more than it is suffering now? Nature, is a part of our being from the earliest human days. We respect Nature and it gives us its bounty, but in the recent past greedy money hungry corporations have made us all so destructive, so wasteful.

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