We will here discuss a possible future energy system based solely on domestic, renewable energy sources of e.g. the types discussed in chapter 2. Since the system must operate within a social framework we have simplified this as discussed in the previous chapter with a Sweden beyond the turn of the century with approximately the same structure as today. What we are discussing here is thus the characteristics of a system such as it could look in roughly 35 years. The components of the system are largely such as those we today know. Some are already in routine operation with good economics and acceptable environmental impacts, others are in various stages of research, development or demonstration. The dilemma of the discussion is as follows. On the one hand we are aware of the fact that it takes a long time in the order of decades to introduce large changes in society. It also takes a long time to prepare public opinion and to plan for such changes. Today's decisions in various sectors will have consequences far beyond the point in time that we have chosen - 2015. On the other hand a characteristic of the previous twenty years has been the rapid expansion of research and development. The revolution in knowledge that we have seen continues, but we believe that its main thrust will be in biology and the earth sciences. The consequences of this for our hypothetical energy system can be far-reaching since it is precisely within these sciences that we see possibilities for a new energy system. In spite of this we believe, particularly considering the long time needed to carry out changes, that we must discuss a hypothetical, possible system 28 in order to make its critical and characteristic features clear. We are not advocating a certain energy system or believe that it is now possible to determine how a new energy system could be shaped. What we are offering is a point of departure for a discussion of the direction of the future energy policy and development in the light of the possibilities and limitations that will be made clear in the discussion. Energy policy and energy systems previous to 1975 was largely a question of energy supply. The major issues concerned the relative importance of hydropower, oil, coal etc, and the most important decisions were made mainly by using economic criteria. Today we see a debate focused on energy use and a consensus exists on the demand for more efficient energy use. A new energy policy must go one step further and stress the links between supply and use so that an intergrated system becomes the point of interest. In that way the use of natural energy flows to meet what we consider our needs can be better understood. Whether society will follow the road we sketch remains to be seen. The uncertainties are several, both in the renewable and the coal/ breeder alternative. New ideas may completely change the situation. But we must today, with the knowledge we now have, try to analyse the situation in all its component parts in order to better understand the conditions on which future energy systems must be based. This is the way to shape our future as consciously as possible. Renewable energy sources can be utilized with different techniques. It then becomes important to observe that energy has different thermodynamic qualities. The energy which is "produced" must have at least tne same quality as the energy used. Table 4.1 gives the 1971 energy use split into different categories of energy quality. (The quality classification is not strictly thermodynamic but also user oriented). Through an effort at more efficient energy use the 1971 29 balance will be changed by 2015. This is true for low temperature When choosing an energy carrier other factors such as its characteristics with regard to transportation and storage must be considered as well as economy. We will return to this. 4.2 The energy system The following thoughts have determined the energy system. An electric grid covering the entire country is an important asset. Hydroelectric power production at present amounts to approximately 65 TWh. Several of the techniques used in Solar Sweden produce electricity; windpower, solar cells and biomass utilized for cogeneration, fuel cells and counter-pressure plants. - The use of fuel outside the transport sector is primarily in the form of firewood and not in refined form as e.g. gas or methanol. This is because of the relatively large transformation losses from biomass to e.g. methanol and because the transportation distances and consequent costs are limited. District heating has been preferred to using chips in small scale systems (e.g. burning in individual houses). The necessary heat can be delivered from power-stations which can also be fired with other fuels during the transition period to biomass production. Combined power and heating plants also contribute to the electricity supply. District heating systems also make utilization of solar heating possible if they have been planned initially for this purpose. 31 In the transport sector we assume that considerably more energy efficient transport systems have been developed (e.g. powered by electric motors). Methanol has been chosen as a fuel because it is easy to introduce, it has good environmental characteristics, it can be used both in Otto cycle engines and fuel cells and it can be produced from biomass. A major part of the energy production could take place within the consumption areas, i.e. a relatively high degree of self-sufficiency compared with today. Local electricity generation using fuel cells and combined power and heat generation give the possibilities for more efficient use of energy (utilization of waste heat). Biomass can, apart from serving as a raw material for energy production, after conversion be used as raw material in chemical industry e.g. for ammonia, plastics etc. This can be done in parallell with methanol production. If the same plant produces chemical raw materials, methanol and waste heat the organizational picture becomes more complex (e.g. how to allocate costs). Figure 4.1 shows the system with the supply on the left hand and the user on the right hand and their interlinkings. The different components are discussed in the following sections of this chapter. |