This book pursues the fundamental idea of using renewable energies in a rational and economic way in order to develop a climate-friendly electricity supply. As the most cost efficient solution, an electricity network for the whole of Europe and parts of Africa and Asia must be found. The sources of renewable and partly decentralised electricity generation could be connected in a comprehensive power supply to meet the electricity needs of an entire region. Czisch examines different scenarios for a CO2 neutral electricity system under different political, technological and economic conditions for Europe and its closer surroundings. The aim is to find in each variation the economically optimal solution, whereby the supply area embraces approximately 1.1 billion inhabitants and an electricity consumption of roughly 4000 terrawatt-hours per annum (TWh/a).
Inspec keywords: power generation planning; power stations; renewable energy sources; power generation scheduling; power consumption; electricity supply industry
Other keywords: wind power; electricity supply scenarios; hydrogen energy; hydropower; fossil-fired power plants; fusion power plants; power plant scheduling; electricity supply; cost-optimised variations; renewable energy; downdraught energy towers; biomass utilisation; power plant planning; electricity consumption; geothermal energy utilisation; solar energy
Subjects: Power utilisation; Energy resources; Power system management, operation and economics; Energy resources and fuels
This book focuses on electricity supply, a component of energy supply that is becoming increasingly important and can be seen as a key to sustainable energy supply. It examines options for a largely CO2-neutral electricity supply for Europe and its neighbouring regions. It explores the question of how the electricity supply should be structured so that it can be obtained in a cost-effective manner based on techniques currently available on the market. The effect on the future electricity supply structure of utilising some of the new technologies that are still being developed is also examined using a number of examples.
The most important result of the scenarios is that electricity can be provided from renewable energy sources alone and that this can be accomplished in an economically feasible manner. Electricity costs in the reference scenario, which are based solely on currently available technologies and costs of electricity, are relatively low at 4.65 €ct/kWh, which includes the cost incurred in electricity supply and all transport expenses to the high-voltage network of the demand regions. With (a) natural gas price amounting to 2.4 €ct/kWhth (2.4 euro-cents per thermal kilowatt-hour), which was the mean price for industrial customers in Germany in 2002, and (b) 55% efficiency for new combined-cycle gas turbine (CCGT) power plants, the cost of natural gas of 4.4 €ct/kWhel would likewise be relatively high. When the remaining capital and operating costs are added to the aforementioned costs, the cost of electricity for new CCGT power plants would range from 5 to 6 €ct/kWhel (even in the event of high power plant capacity use), which is substantially higher than in case of the reference scenario.
This chapter presents research efforts in Europe and its neighbor on future energy supply. It gives an overview of energy researches in various European and neighboring countries such as the solar, wind, and hydropower in Germany, the renewable energy generation in Austria, and the solar thermal power plant in North Africa.
Direct utilisation of solar energy presents the greatest potential of all renewable energy sources due to the global radiation supply, which is equivalent to around 7,000 times the current worldwide primary energy demand. This supply is characterised by a very marked geographical dependency, both in terms of quantity and temporal structure. For example, the annual global radiation in central Europe, northern Morocco/southern Spain and in favourable locations in Africa around the 15th parallel north is approximately 1,000, 1,800 and 2,500 kWh/(m2a), where the average radiation in each of the months with the lowest radiation amounts to approximately 17%, 27% and 77% of that in the month with the highest radiation. There are also large local differences in the proportions of direct and diffuse radiation. In the three regions mentioned above, the annual average ratio of diffuse to global radiation is stated as 55%, 30% and 25% of global radiation on a horizontal surface.
The use of wind energy has become increasingly important in recent years. Since the 'modern' use of wind power for electricity supply started in Denmark and the United States at the beginning of the 1980s, installed capacity worldwide has risen to more than 39 GW at the end of 2003, with Germany and Spain also being responsible for growth in the last decade to a significant degree. At the beginning of 2004 around 77% of the global capacity was installed in these four countries. Use of wind power was characterised by significant growth during both these decades. The worldwide installed capacity of wind energy converters, commonly referred to as wind turbines, doubled around every 32 months in the two decades from 1983 to 2003 and grew annually by around 30% on average,1 both in the first and second decades. This rate of expansion was achieved by a rise in the annual growth rate of new instal lations averaging 15% between 1983 and 1993, and further increasing to 33% between 1993 and 2003. At the same time there was a constant increase in the rated capacity of individual wind turbines. In Germany the larger proportion of newly installed capacity is at present provided by powerful wind turbines with rated capacities over 1,000 kW. The megawatt class wind turbine with rated capacities of 1-2 MW continually gained ground after its commercial introduction at the beginning of 1995, attaining a share of the rated power of more than a third of new installations by the start of 1998, and had apparently passed its zenith in Germany in 2002 at more than 70%, 'ousted' by even larger turbines. A long side turbine capacity the hub height (HH) has also increased from around 30 m at the beginning of the 1990s to an average of almost 80 m in 2002, which helps increase yields due to greater wind speeds. With technical development, the costs of wind energy have fallen sharply. When the wind industry started to develop in California in the early 1980s, electricity from wind energy cost 38 USct (cents) per kilowatt hour. Since then, costs at the best sites have fallen to USct or less, and some long-term supply contracts have been signed for USct per kilowatt hour. If these figures and the global installed wind turbine capacity are applied, cost reductions of 24% are achieved for a doubling of the output of all installed turbines. The development of wind energy yield therefore follows a very dynamic course, both from a technical and an economic angle.
The energy content of the annual global formation of plant biomass is estimated to be around 800,000 TWh, of which the largest portion of 42% occurs in wood land, 38% in the oceans, 9% in grassland and only 5% in arable areas. This corresponds to around seven times the worldwide primary energy consumption or 0.1% of the solar radiation that penetrates the atmosphere. Various sources give relatively similar results for the global new production of biomass. However, things look different when it comes to energetic utilisation. Very different figures are given even for the assess ment of current biomass utilisation. S. Swinehardt (1994) compared various literature sources of which four gave figures on the energetic utilisation of biomass for 1990. The values lie between 9,400 and 21,000 TWh. Even with commercially traded biomass, measurement of the quantities appears to be beset with problems, so that the figures cited from three sources differ widely, with values between 1,700 and 4,800 TWh.
Hydropower is a significant contributor to global electricity production. In 1995 hydropower was responsible for 19% of the total net electricity production, accounting for 22% of the 2,950 GW of power plant capacity installed worldwide. For Western and Eastern Europe (including the former Soviet Union), these figures amounted to 21% and 19% of the net electricity production (approximately 500 and 270 TWh), respectively. Russia accounted for the majority of Eastern European electricity production from hydropower, whereas just under 110 TWh, or approximately 65%, was generated in the Asian part of the country. At 2.3% p.a. between 1980 and 1995, the average global increase in electricity production from hydropower lagged behind the 3.1% p.a. increase in electricity production overall. It was anticipated that by 2010, there would have been a further 2.4% p.a. increase in electricity production from hydropower, whereas global electricity production was only expected to rise by 2.8% p.a. Only a relatively small rise in the use of hydropower of approximately 1% p.a. is anticipated for Western Europe.
High temperatures prevail inside the Earth's core: 99% of our globe is hotter than 1,000 degrees and only 0.1% is cooler than 100 degrees C. For this reason, a continuous heat flow penetrates to the (cold) surface through the Earth's crust. It is not the author's intention to decide whether or not it is meaningful to term exploitation of the geothermal deposits beyond the natural heat flow as renewable. As a consequence of very strict criteria, only use of the natural heat flow is termed 'renewable' in the scenarios. However, in this case, selective and temporary exploitation of the stored energy is included, with periodical return to the regenerated former locations.
The use of downdraught energy towers (DETs) is a very promising possibility of generating electricity from renewable energies, although it has so far only been theoretically investigated. As no DET has yet been built, the intention is only to include its use in the speculative part of this study, and thus only in appropriate scenarios. A DET uses solar energy stored in the atmosphere to generate electrical current.
If electricity production is based to a large extent on the use of wether dependent generation systems and if the different dynamic behaviour of these systems does not bring the required balance in production, then it is necessary to adapt to the fluctuating behaviour of the energy source used by providing sufficiently large backup-reserves. This function may be taken over by storage systems. The storage facilities must be dimensioned according to the time con stants that dominate the fluctuating behaviour of the energy source to be used. One possible way of storing energy is by the use of hydrogen. Hydrogen, with a share of 15.8%, is the third most common element, after oxygen and silicon, occurring in the Earth's crust, oceans and atmosphere. However, it is found in its free form in the air as H, with only an infinitesimally small share of less than 0.001%. So hydrogen in its pure form does not directly exist as a natural resource and can merely be obtained from various substances as a secondary energy carrier and by expending energy. Of course, each such process, like all real processes, involves losses; that is to say, the educts contain more energy than the product hydrogen does subsequently. This disadvantage, however, may in some circumstances be taken into account if the utility value of hydrogen is higher than that of its precursors. The storability of hydrogen speaks in favour of its production and future use in electricity supply, which is why it is potentially suitable for use in electricity supply for backup purposes. This way of using chemically storable energy carriers is sometimes also considered necessary to enable large proportions of renewable energies to be used in the electricity supply. Theoretically, relatively high efficiencies can be anticipated in the production of electricity from hydrogen, which, where appropriate, may make up in part for the disadvantage of other energy losses in the hydrogen chain. At any rate, hydrogen is suitable for energy storage and is a transportable energy source.
It has not yet been possible to assume that the use of fusion power plants (FPPs) will be viable. However, due to the enormous energy potential that could be tapped through them, this possibility is being actively explored. One technology that has been developed in this regard is plasma fusion, in which a plasma of heavy and superheavy hydrogen (deuterium and tritium) enclosed by magnetic fields is heated up to the temperatures necessary for fusion. Along with the huge potential, one advantage of plasma fusion compared to the conventional use of nuclear energy is seen in the relatively short half-life of the radioactive materials generated, which is said to be only 1-5 years and the radio toxicity of which, depending on the power plant's design, is said to decay to the upper values of normal coal ash from coal-fired power plants after only a few centuries. At present, efforts in plasma fusion research are aimed at generating more energy in the plasma than is required to heat it up so that once this stage is reached, a net surplus can be achieved which enables electricity production. Surplus production should be successful for the first time in the planned international thermonuclear reactor (ITER) with an envisaged thermal capacity of Cth = 1.5 GWh. FPPs are expected to achieve production maturity around 2050, according to information from research establishments involved in its development.
In some scenarios, the use of fossil-fired power plants is permitted for backup purposes or for producing limited fractions of the electrical energy. Although such power plants are not the point of considerations in any of the scenarios, in this chapter the basic assumptions about these power plants will be a determining factor for the outcome of power plant usage and selection planning in these scenarios. For this reason, the aim of this chapter is to look briefly at the power plants and the fuels used.
As shown in the previous chapters, networking electricity consumption and generation via a large-scale high-capacity 'supergrid' would have a positive impact on the use of weather-dependent generation units and all grid storage components. Such a supergrid would also allow for the achievement of beneficial electricity consumption equalisation effects.
This chapter discusses power plant scheduling and selection planning.
This chapter discusses, by means of various scenarios, the impact of various framework conditions and restrictions on the structure and use of the resulting optimal fleet of power plants.
This study shows that the renewable energy potential is more than adequate for establishing an electricity supply system that is solely based on renewables. This statement explicitly not only applies to the potential generation, but also takes into account the availability characteristics. It was therefore logical to ask how a renewable electricity supply system should be configured in order to make it as cost-effective as possible. This is where the optimisation approach for power plant usage and selection planning comes in, which provides a number of solutions for a wide range of scenarios.
This Appendix shows the calculation methods used for: solar energy utilisation; wind energy; producing the time series of allocated heat demand in biomass power plants; downdraught energy towers; and geothermal energy utilisation. It also shows how the time series for electricity consumption was created.
The scale of the optimisation problems that have to be solved for the scenarios makes it necessary to implement a systematic formulation and to automate it as far as possible. For commercially available solvers that are suitable for linear optimisation problems, the formulation of the optimisation problem requires the creation of a so-called MPS file that contains all equations and inequations for the respective optimisation problem. MPS is the standard format for such a file. The approach described in this Appendix was used to simplify the creation of the MPS files for the various optimisation problems in the different scenarios.
The optimisation problem for the power plant usage and selection planning procedure must be mathematically characterised in such a way that it can be solved using the defined optimisation method. This Appendix (a) provides a rough overview of the optimisation problem formulations that were used to elaborate the various scenarios, and (b) describes the key principles that were applied to modelling of the linear optimisation problem.
This Appendix shows seven maps: (1) segmentation of the supply area of the 19 regions; (2) population centres and centres of photovoltaic generation; (3) power plant usage and selection planning and envisaged HVDC feed-in locations; (4) centres of onshore wind generation; (5) centres of offshore wind generation; (6) approximate locations of parabolic trough power plants; and (7) centres of generation from energy towers. Also supplied is a table showing the allocation of countries to the various regions.
This Appendix gives three tables of symbols that are used in this book: (1) a list of Latin symbols; (2) a list of Greek and other symbols; and (3) a list of indices (subscripts to the symbols).
This section lists terms used in power engineering.
