There is a force without a source

Alternative energy: The energy transition can be achieved with these sources

Fossil fuels still provide most of the world's energy needs. From an economic point of view, however, the extraction of these raw materials is becoming increasingly expensive. Alternative sources have to be developed in order to sustainably secure the supply and the growing demand.

Photo: panthermedia.net/violetkaipa

What is alternative energy?

Energy is life: every living being is part of the energy cycle and needs it in order to exist. This energy is not lost, but is returned as part of the whole in a different form. By interpreting the law of conservation of energy, humans are able to develop mechanical and technical systems to convert energy as required. In addition to medical supplies, clean drinking water and food, energy in the form of electricity, heat and fuel is a matter of course today. The required performance grows with the respective demands. For a long time, fossil fuels have been the main fuel of the energy industry. However, progress demands alternative energyin order to meet future requirements, because raw materials such as coal, uranium, oil and gas are exhaustible resources.

Researchers and developers around the world are working on the implementation of innovative processes for generating energy without having to resort to fossil fuels. Energy carriers can come from finite as well as from inexhaustible sources. The alternative energy deals with both forms of starting materials. The technical term is to be delimited here Renewable energy or regenerative energy. This uses only CO2-neutral primary sources such as wind, water and solar energy. This group also includes biomass and geothermal energy (geothermal energy). This essentially includes all deposits that are inexhaustible. Furthermore, switching to alternative sources will be cheaper than their fossil counterparts in the near future. Various options for regenerative energy generation enable the optimal use of existing, natural sources, exactly where maximum potential is possible.

Due to the rethinking of the population, it is now considered good form to grow your own vegetables in the garden in order not only to relieve the household budget, but also to contribute to the ecological balance in a certain way. State subsidies give homeowners the option of installing a solar system on the roof. The electricity generated can be used outside of the hours of sunshine with the help of an electricity storage system. The photovoltaic system is able - depending on its size - to supply the entire household with energy in a decentralized manner. Using your own solar collectors can cut electricity costs by more than half. As a result, the purchase of such a system pays for itself after around two years.

This contribution is intended to serve as the basis for a comprehensive overview of the topic of alternative energy with a focus on renewable energy sources.

Historical facts about alternative energy generation

Alternative energy forms an integral part of today's energy generation and can be found everywhere - whether solar collectors on roofs or wind turbines that characterize the landscape. The electricity that flows through the network and is drawn from the socket by the end user contains a certain percentage of the energy that comes from alternative sources. Bioethanol is even added to fuels such as gasoline in order to optimize the ecological balance. This could create the picture that the development of alternative energy generation can be attributed to the modern era. The fact is, however, that humans have been using the elements for much longer than one might think.

For a good 5,000 years, positional and kinetic energy have been used to drive mechanical constructions such as sawmills or grinders with water wheels and wind turbines. The natural warmth of the sun has always been incorporated into the architecture of buildings in order to have a positive influence on the indoor temperature. Geothermal energy has been used since ancient times to heat bathhouses.

With electrification, people opened up new possibilities in production and technology. The next logical step was to generate electricity from natural resources. In 1839, Henry Becquerel discovered the photoelectric effect, a method to generate electrical energy from two electrodes using solar radiation. Werner von Siemens invented the electrodynamic generator in 1866. Hydropower plants have been generating commercially used electricity since 1880. The first wind turbine followed at the end of the 1880s. Electricity was generated from geothermal energy as early as 1904. From Becquerel's research on solar energy, Charles Fritts developed the first functional solar cell in 1954. In 1961, the first tidal power plant opened up the tidal range as a source of energy.

These are just a few milestones on the way into the age of alternative energy generation.

Diverse possibilities of energy generation

Primary energy can usually not be used directly by the consumer. In most cases, this is converted into secondary energy or refined using various processes. Unfortunately, only a few forms of alternative energy generation are capable of base load, as not all energy sources guarantee a constant supply. For the optimal use of the available energy, there are various energy sources that are used depending on the location, such as

  • Wind energy
  • solar power
  • Hydropower
  • Geothermal energy
  • and energy from biomass.

Wind energy

The generation of electricity by means of wind power is the most important use of wind energy today. In large systems, the kinetic energy of the wind on rotors is translated into torque and converted into electrical current in electrodynamic generators. Modern systems use rotor blades that are in the wind according to the principle of lift, like an airplane wing. Under optimal conditions, these systems could even use up to 59 percent of the pure wind power to generate energy. Whole “wind parks” on land or offshore, at sea, provide clean, carbon dioxide-neutral electricity. However, the majority of the plants are on land. Estimates assume that the expansion in the offshore sector will only reach 20 percent in the coming years. The plants built so far have a nominal output of just under 540 gigawatts, which is just under four percent of the world's electricity demand. However, this nominal power does not indicate the actual yield. Air density, wind speed and rotor area determine the performance of the wind power plant. The systems have to be shut down when the wind is too strong and generate less electricity when the wind power is too weak. This inconsistency does not guarantee constant profitability. Another aspect is the location factor of the plant. On the flat land, where the air flow is not distracted by elevations or vegetation, the yield is much more continuous than in the mountains. There the air is thinner and the currents less predictable. For these reasons, wind power cannot be used as a base load.

48.9 percent of all of the alternative electricity generated in Germany in 2017 came from wind energy.

Solar energy

The sun, the energy provider of our planet, is by far the most important source of energy. Starting with photosynthesis and the climate, without them, no life on earth would be possible. It supplies us with oxygen and food through the plants. Their heat heats the surface of our planet and drives ocean currents and winds, which are essential for our stable climate. The energy of the sun, which is absorbed by the earth's surface, would be sufficient to meet the world's energy needs ten thousand times over. The generation of solar energy is based on two pillars. One is the simple heating of water using solar thermal systems, for example on the roofs of homes or solar farms. The hot water is used to heat the domestic water. Electricity is generated by bundling the sun's rays in solar thermal power plants, which consist of complex mirror systems. These heat a central absorber and generate electrical energy with the help of a heat transfer medium and steam turbines. The second is the electrochemical conversion of radiation into electricity. Solar cells capture the radiation and semiconductor technology transforms it into electricity. These systems are often found on large roof areas, such as apartment buildings or industrial plants, as well as on fields. In principle, solar energy is available everywhere. Unfortunately, it is also subject to daily and seasonal fluctuations. In our latitudes, solar systems rarely have an optimal level of efficiency. At night, when the sun is not shining, no energy is generated either. If the system is dirty, covered by snow, or the angle of incidence is too steep or too flat, this lowers the energy yield. Complex control and storage systems are required for solar energy from solar cells. In 2017, all solar systems worldwide had an output of 390 gigawatts. That is around two percent of the world's electricity generation. Estimates assume that the share of solar energy could grow to 13 percent by 2030.

Within the processes for alternative energy generation, the share of solar power in Germany was 18.3 percent in 2017.

Hydropower

Hydropower means using the flow of water to generate electricity using turbines in generators. There are different forms of hydropower plants. The most common representatives are pen power plants. Like water wheels, these belong to the run-of-river power plants and use the pure flow force of the water. You are standing in an artificial bay on the edge of a river. Due to the construction, the natural course of the flowing water is not narrowed and floods can flow away unhindered. In run-of-river power plants with threshold operation, the river water is dammed up in weirs or reservoirs. During load times, the water is passed through turbines, which on the one hand leads to optimal utilization due to the difference in height and on the other hand covers the increased electricity demand. Storage power plants store a large amount of water in large reservoirs or dams so that it can be fed through turbines if necessary. The construction of storage and run-of-river power plants with threshold operation differs only slightly. Due to the large flow, storage power plants serve more to cover peak loads, run-of-river power plants usually only accumulate for the purpose of greater head. When there is an excess of electricity, pumped storage power plants pump the water from a lake into a reservoir at a higher level, so that it can be fed back through the turbines if necessary.

The tidal power plant uses the movement of the water between ebb and flow to drive the turbines. At locations with marked differences in height between the tides, turbines built into dams through which the water masses are directed are driven at every tide. The salt water damages the turbines. There are only a few suitable locations and the inflexibility of the tides make this form of energy generation uneconomical.

The power of water is basically reliable, is well suited as a storage medium and can be called up within a very short time if necessary. Therefore, hydropower plants can be used to cover base loads and as a supplement to peak load times or in the event of failures.

In 2017, 9.1 percent of all alternative electricity generation in Germany came from hydropower.

Geothermal energy

Geothermal energy refers to the generation of heat and electrical energy from the heat of the earth's core and from the decay of radioactive elements in the earth's crust. It is roughly classified into near-surface and deep geothermal energy. Since the earth's crust is not influenced by seasonal temperature fluctuations, the inlet temperature in geothermal systems is always constant. The near-surface geothermal energy is defined with boreholes of up to 400 meters. It is used to drill into the upper crust of the earth. The temperature, which increases by around 3 degrees Celsius per meter, is made usable by means of geothermal collectors, geothermal probes, groundwater wells or concrete components in contact with the ground (“energy piles”). These systems are well suited, for example, to supplying homes, industrial buildings or apartment buildings with inexpensive hot water or heating systems. There are areas with geological peculiarities, such as near-surface magma layers or thermal springs. Here the temperature can be sufficient to drive steam turbines to generate electricity.

Deep geothermal energy is divided into two processes. With the hydrothermal method, groundwater reservoirs are connected to the system at a great depth at the appropriate temperature. The petrothermal method uses the heated bedrock as an energy source. These two systems are mainly used for district heating systems that supply entire villages or city districts. In addition, higher temperature levels are reached in deep boreholes, which makes the generation of electrical power by steam turbines significantly more effective and cost-effective. In 2015, plants with a total thermal output of 70,270 megawatts and an electrical output of 12,590 megawatts were installed worldwide. In addition, geothermal heat production reduces the need for fossil fuels. In 2015, it replaced over 52 million tons of crude oil and reduced CO2 emissions into the atmosphere by 148 million tons. The continuity of geothermal energy makes it a good source of clean energy, especially in the form of district heating.

Since Germany unfortunately does not have good locations for generating electricity using geothermal energy, this only made up around 0.1 percent of Germany's total alternative electricity generation in 2017.

Energy from biomass

Biomass is one of the most flexible alternative methods for generating energy. This includes all organic substances that generate energy through fermentation or combustion. Methane gas is obtained from vegetable and animal waste. This can be converted into electricity and heat by gas turbines, and transported further by local or district heating. The electricity generated in this way is fed into the grid. The intermediate storage of methane gas takes place in large tanks. The methane gas is fed into the natural gas network in the form of biogas or used as fuel for gas-powered vehicles. Combined heat and power plants (BHKW) burn solid materials, for example wood waste, to generate heat. Through a combined heat and power system, electrical energy is generated at the same time and the waste heat is used for local and district heating. On a small scale, miniature CHP units or wood pellet heating systems in basements provide CO2-neutral heat in private homes or apartment buildings. Biomass is obtained directly from renewable raw materials or indirectly from waste from farms. Plants, for example, bind carbon dioxide in the course of their life. Animals produce a comparable amount through their excretions, which is released again when the manure is burned. The incineration or fermentation is climate neutral compared to fossil fuels.

The share of biogas in alternative electricity generation in Germany was almost 15 percent in 2017. These solid fuels took up 4.9 percent in this ranking and only 0.2 percent came from the liquid biogenic fuels.

Fuels from alternative energy sources

The primary goal of alternative energy generation is currently the generation of electricity in order to counteract the decreasing amount of fossil fuels. It can also be used to heat up domestic water and to control the temperature of buildings. In road traffic and in industry, large amounts of conventional fuels have also been required so far, which is why the use of alternative options is also being targeted here. For this reason, research is looking for methods to produce environmentally friendly alternative fuels in this segment too, such as

  • Biofuel
  • and hydrogen.

Biofuel

Biofuel is obtained from biomass. This can result in pure alcohol. Cellulosic ethanol is made from green parts of plants, bioethanol from sugar beet. From a chemical point of view, both products are identical. Biodiesel is produced by esterifying methanol or ethanol with fatty acids. Alternatively, due to its properties, rapeseed oil can also be used directly as fuel. These fuels can power the engines of vehicles, machines and power generators, for example.

hydrogen

Hydrogen is in the first main group of the periodic table and is considered to be the most reactive element. When it reacts with oxygen atoms, it releases enormous amounts of energy. For this reason, hydrogen is ideally suited to power vehicles and machines. In natural occurrences, however, this is bound to other elements, but can be separated from other substances by two processes. It is either separated from the molecular chains of crude oil as a by-product of crude oil refinement or obtained from natural gas or coal. However, these processes do not make the production of hydrogen climate-neutral.

Biomass offers an alternative to fossil fuels. Hydrogen can also be extracted from it by heating it.Biomass consists for the most part of carbohydrates and other compounds containing hydrogen and carbon. The oxygen required for the reaction is also already contained in the energy source.

The other common method is to split water molecules into hydrogen and oxygen using electrolysis. If the electrolysis is implemented with alternative energy sources such as wind or solar energy, the hydrogen produced is also climate-neutral. The hydrogen can thus serve as a storage medium for other alternative energies if there is an excess of energy. The hydrogen is mixed with oxygen in a fuel cell. The reaction of the two elements releases energy, which is converted into usable direct current by an electron-conducting membrane.

Other methods of producing fuel are the extraction of energy from sewage and landfill gases as well as the direct recycling of edible fats, which are used, for example, as fuel for public city traffic.

Feeding electricity into the commercial network

The infrastructure of the power grid makes it possible to feed in any form of electrical power, whether it is generated electricity from fossil fuels or alternative energies. That is why the electricity that we draw from the socket consists of a combination of all types of generation. Billing is easy. The operator of the plant is paid a certain amount per kilowatt hour. This varies between 8.44 cents and 12.20 cents depending on the size and type of the system. In the event of network-related shutdowns, a certain percentage is paid out as a replacement service. Basically, a distinction is made between three options - these include

  • pure feed
  • Self-consumption and feed-in
  • as well as self-sufficient systems or island systems.

Pure feed

Photovoltaic systems now make a significant contribution to positively influencing climate change. This is achieved because the conversion process does not emit any greenhouse gas into the atmosphere. If the purchase is not worthwhile for your own energy needs, it still makes sense to think about installing such a system on your own roof. Not only large system owners with power plants, wind farms or large-scale solar systems can benefit from the pure feed into the commercial power grid. The systems are connected directly to the local energy supply and contribute to the density of energy availability. The owner of the photovoltaic system continues to cover his own energy consumption through the energy supply company. The electricity fed into the grid can then be sold at a profit.

Self-consumption and feed-in

First, the alternatively obtained energy from the existing systems is fed into the private network, where it is freely available to the owner of the system. The electricity generated is usually able to cover the base load. When consumption is higher, energy is taken from the commercial power grid. If, however, more electricity is generated by the system than the owner needs at the moment, there is a surplus that can be transferred to the public grid. A special configuration of the electricity meter is required for accurate billing. In contrast to conventional electricity consumption, a separate meter is required for a feed-in, which records the fed-in energy in kilowatt hours. This allows the self-consumption and the electricity provided to be calculated. This calculation is regulated on the basis of the Renewable Energy Sources Act (EEG). Another possibility to use unused electricity at a later point in time is to store it in accumulators. These enable electricity to be drawn even when no energy is being produced in the system.

Autonomous systems / island systems

A whole range of small devices, such as clocks, pocket calculators or garden lights, which, for example, ensure their energy supply through their own solar cells, lay the foundation for so-called island systems. Uncomplicated access to the energy supply network is not possible everywhere, so this solution is used in various areas. A portable solar collector can generate electricity almost anywhere in the world. This can be used directly on site or excess energy can be stored in an accumulator. Larger systems even supply mountain huts, weather stations or toll bridges on motorways, for example. At fixed locations, wind or water power, such as a simple wind or water wheel, can be used. Probably the most important criterion of self-sufficient systems is that they are not able to feed excess energy into the grid. This is why an energy storage device is necessary that stores this excess until it is needed. Probably the most concise example of island systems are satellites that are supplied by their solar panels.

Advantages and disadvantages of alternative energy

The great potential to save environmentally harmful emissions, which alternative energy sources offer, grants a multitude of advantages compared to fossil fuels as an energy source. Of course, not only the positive characteristics become visible, but also the negative aspects. This includes questions from the following areas:

  • environmental Protection
  • Effectiveness and amortization of alternative energy sources
  • Base load coverage
  • Peak load coverage
  • Energy storage

Alternative energy in terms of environmental protection

Reducing environmentally harmful emissions through conventional energy generation is the only option to continue to maintain planet earth as a habitable habitat for fauna and flora. Greenhouse effects from the burning of fossil fuels have already warmed the earth by 0.8 degrees Celsius compared to the pre-industrial age. At first glance, this value appears harmless, but on closer inspection it can be seen that even minimal changes can permanently change the ecological balance in a negative sense. This creates chain reactions that can have catastrophic effects on ocean currents, climate and weather phenomena. The generation of CO2-neutral electricity, heat and energy is definitely in the interest of environmental protection, but on closer inspection this is also characterized by negative aspects.

Solar cells require rare raw materials for their production. These are mostly promoted and processed under inhumane conditions in countries in Africa or China. In the extraction or refinement of materials in these countries, the handling of environmentally harmful chemicals is characterized by improper safety regulations. On the other hand, a relatively large amount of energy, mostly from conventional energy sources, is required in production. In most cases, a solar module only pays for itself after a period of use of between nine months and three years. Only then is the electricity supplied environmentally friendly. The location of the plant can also have an impact on the environment. On roofs, the surface is almost harmless to nature. Therefore, these systems are less important. The open spaces next to traffic routes or on areas not used for agricultural purposes, however, which are occupied by the modules and high fences, must be viewed critically. Vegetation is changed, the soil is compacted. The habitat can then no longer be used for many native animal and plant species. Although other species can repopulate the habitat, the species shift has far-reaching effects on the ecological cycle.

Hydropower plants influence the ecosystem of water. Fish and birds close to the water or direct water birds are directly threatened by the turbines and impellers. The structural alteration of river banks or courses to channel the water flow interferes with the natural habitat of the animals. Reservoirs destroy the habitats of land creatures. The straightening of the watercourse, as well as obstacles in the form of power plants, favor the creation of floods, which can only flow away under difficult conditions due to these interventions.

Geothermal energy interferes with the nature of the earth's crust. Geological features are further destabilized. The drillings, especially in large-scale deep geothermal projects, lead to a perforation of the earth's crust. This can favor earthquakes.

Wind turbines, on the other hand, threaten the habitat of the birds. Many of them die every year on the rotor blades of the wind turbines. Of course, this also includes endangered species of birds. In addition, the soil around the foundations is compacted, which changes the vegetation. Furthermore, natural habitats are being destroyed by the access roads.

Biomass consists of raw materials of vegetable and animal origin. The production relies on high starchy plants, the cultivation of which has a negative effect on the ecosystem. The massive demand for energy leads to a competing use of land between conventional agriculture and the cultivation of biomass-compatible fuel. Perennial monocultures made from corn or fast-growing woods leave the soil sterile. Further areas have to be developed, which in turn endangers the biodiversity and habitats of native animals.

Another difficulty is the storage of the electricity generated. Accumulators, with their highly environmentally harmful carrier materials, are problematic even during manufacture. Recycling turns out to be even more difficult. They also have a short service life and little storage capacity compared to their manufacturing costs.

Nonetheless, alternative energy generation methods represent a clean and comparatively environmentally friendly counterpart to the utilization of fossil fuels

Effectiveness and amortization of alternative energy

The acquisition of such systems is costly. Geothermal energy or photovoltaic systems for end users can quickly cost tens of thousands of euros. The savings compared to the purchase of fuel and electricity, as well as the profits from the sale of the PV electricity, offset these acquisition costs over time. The amortization period is the time it takes for the system to generate investment costs and profits. The acquisition costs as well as ancillary costs and interest are included. In the case of photovoltaic systems, this is between 11 and 15 years, depending on the financing model and purchase price. Another three years are added for the energetic amortization. Solar collectors for hot water preparation and to support heating pay off after about 15-20 years. In comparison to gas heating, geothermal heat pumps for homes pay for themselves after ten years - with oil heating after five. Large systems are often built in the most favorable locations, which shortens the time until the initial expenses are covered by the resulting income. The energetic amortization of large wind turbines is around three to seven months, the economic amortization around ten years. In the case of small systems, this can be estimated at around 20 years due to the lower yield. Hydropower plants are rarely used in the private sector. They are associated with high acquisition costs. Because these exist in various designs and sizes, it is simply not possible to state the amortization. The advantage, however, is the long service life of these power plants, which in individual cases far exceeds their economic efficiency.

Base load coverage

Base load refers to the load on a power grid that is not undershot during a day. This is preferably provided by sluggish, difficult-to-control run-of-river power plants and coal or nuclear power plants. Due to their low fuel costs but comparatively high fixed costs, the latter are forced to constantly generate energy under full load in order to be able to operate economically. Modern reactors are able to regulate the power in load following operation. However, this process takes two hours or more, and even 12 hours if the system is completely switched off.

In the case of coal-fired power plants, controllability is associated with even higher costs and time expenditure. Driving back is achieved by adding less fuel. If the temperature level falls below a certain value, it is no longer possible to generate energy. A complete shutdown is necessary. Starting up shutdown coal-fired power plants usually takes more than 12 hours.

The largest part in the alternative energy sector is made up of photovoltaic and wind power systems. This can lead to a so-called wind hole in good wind conditions or a cloudless sky. In this case, the electricity produced exceeds the base load, so other power plants have to be cut back. At night, when consumption is lowest, the base load is defined solely by continuously producing industrial plants, street lighting and permanent consumers. The slow throttling of conventional base load power plants increases the purchase price of electricity disproportionately. For this reason, the base load of energy supply companies can be artificially increased by creating additional electricity requirements during off-peak times through night storage or pumped storage power plants.

The base load in Germany was around 45 gigawatts in 2017.

Peak load coverage

However, by covering the base load alone, a stable power grid cannot be maintained. More energy is required during the day than at night. Photovoltaic systems, storage power plants and, in the event of energy bottlenecks, also pumped storage power plants absorb these medium to peak loads. PV systems, run-of-river power plants with threshold operation and storage power plants are used for the medium load. Modern PV systems have an inverter that allows central control or shutdown if too much electricity is produced. This does not detract from the feed-in priority, but it allows alternative and conventional technologies to be brought together more harmoniously. Hydropower can be switched on if even conventional base load power plants, wind energy and PV systems together do not generate enough power.

Energy storage options

The overproduction of energy from alternative sources only makes sense if it can be temporarily stored in energy storage and is available from there at any time. This makes it possible to absorb load peaks in the power grid. Depending on the wind or weather conditions, this excess energy is used to ensure the power supply even when it is cloudy, calm or at night, as required. Electricity storage systems ensure the necessary flexibility in the age of decentralized energy production.

This is achieved through a range of storage options, which differ in terms of performance, efficiency, energy density and construction costs. Furthermore, a distinction can be made between short-term and long-term storage. The energy introduced is usually called up in the same form in which it was stored. Nevertheless there are exceptions. For example, in some plants electrical energy is converted into hydrogen and stored in hydrogen tanks.

With compressed air and pump storage as long-term storage, a solid coverage of peak demand is possible. These storage systems can be discharged within two to 24 hours and have a capacity of between 500 megawatt hours and a few gigawatt hours. The latter are limited solely by the size of the pumped storage lake. Electro-chemical storage systems are used in cases and areas of application in which storage over a longer period of time is necessary, such as in reserve storage systems or in electromobility. These consist primarily of lithium-ion accumulators or redox flow batteries. The former are mostly used in road traffic. The latter store energy in chemical compounds within a solvent. Due to their relatively high storage capacity, redox flow batteries are used in cell phone base stations or as buffer storage in wind turbines.

Less expensive lead-acid batteries require some safety precautions during storage and operation. However, they are in no way inferior to their competitors and are used in storage systems with a capacity of up to around 50 megawatt hours.

Short-term storage, however, is out of the question for storage. Compared to long-term and electro-chemical storage systems, these can only store small amounts of energy and serve exclusively to stabilize and maintain the network.

The demands on storage technology are high. For an economical and sustainable integration into the energy network, it is necessary that energy storage systems are above all energetically efficient, safe and environmentally friendly (in terms of production, use and disposal). The longest possible service life, in the form of many charging cycles, is also a necessity.

Major disadvantages of storage systems, in contrast to continuous energy producers, are primarily additional acquisition costs, space requirements, increased maintenance and control costs and the limited shelf life of accumulators.

The most common types of storage in Germany are long-term storage, such as pump storage, battery storage and the storage of hydrogen or synthetically produced methane in underground caverns. The latter enable the storage of up to two terawatt hours of energy across the country.In the automotive or transportation industries, electrical energy is either stored in mobile batteries or fuels obtained from renewable energies, such as hydrogen or methanol, are used in fuel cells.

Many different storage technologies have been developed in recent years. There is a specially designed storage type for almost every area of ​​application. Although some solutions are still in the development phase, systems such as pumped storage plants or battery parks made from lead-acid accumulators have been used for efficient energy storage for decades and are reliably doing their job there.

Cost-benefit analysis of alternative energy generation

The age of decentralized energy production begins with the intention of relieving the burden on the environment and yet not accepting any restrictions in energy consumption. Energy in the form of heat or electrical power is no longer only offered by large producers, but increasingly also obtained in private households. This fact enables, along with the expansion of solar and wind power plants in the public sector, that large amounts of harmful greenhouse gases can be saved. In many construction projects, however, valuable agricultural or natural land is built, to the detriment of the local flora and fauna. In addition, access roads to solar or wind parks will be built, which will take up additional space.

Alternative energy is definitely associated with higher costs in terms of generation. The production of solar cells or generators in wind turbines requires rare metals and is nowhere near as environmentally friendly as it appears at first glance. In addition, increased maintenance is necessary, especially with wind turbines. With an average lifespan of around 30 years for crystalline solar cells, such a system pays for itself during its useful life - usually after just a few years when energy is fed into the grid. Wind turbines or wind turbines, on the other hand, are only designed for a service life of 20 years, after which they have to be dismantled or replaced.

A big advantage of the alternative energy generation, however, is the independence from the power supply network, as well as the possibility of feeding self-generated electricity into the commercial network.

The coverage of the base load is still left to the large, conventional power plants and run-of-river power plants. These are sluggish and difficult to control. By using batteries or other energy storage devices, it is possible to cover peak loads and, if necessary, to react quickly to fluctuating demand. Wind and solar power plants generate a considerable amount of energy - but they are dependent on wind and sun. A constant supply is therefore not given, so that energy storage devices have to be interposed here as well.

Depending on the type, these storage systems can take up capacities in the gigawatt range, but cause additional costs during construction and operation. In addition, there is a percentage loss of energy that occurs during storage or energy conversion - this is up to 55 percent for long-term storage systems, up to 45 percent for electro-chemical storage systems and up to 80 percent for hydrogen storage.

Important regulations

Alternative energy sources have great future potential in terms of climate protection. They also help to minimize the depletion of fossil fuels. The possibilities of obtaining alternative energy are almost limitless. Nevertheless, dealing with exhaustive and infinite resources requires some regulations that are anchored in guidelines and laws. This includes, among other things, climate goals that are pursued by politics or the promotion of renewable energy systems. The most important at a glance:

  • EU Renewable Energy Directive (Directive 2009/28 / EC)
  • EEG and EEG surcharge
  • Biofuel Quota Act

EU Renewable Energy Directive (Directive 2009/28 / EC)

With the Renewable Energy Directive (EC), in full Directive 2009/28 / EC, it was bindingly stipulated for the member states of the European Union that 20 percent of the total energy consumption in Europe must be made from renewable energies. For the first time, it created a Community directive for the use of renewable energies in the three energy sectors of electricity, heating / cooling and transport. Each member state was assigned a binding, reasonable quota of renewable energy generation, so that the overall result for Europe is 20 percent. For Germany this rate is 18 percent. The agreed measures include the transport sector as well as the sustainability requirements for the various procedures, the adaptation of building regulations and the simplification of the administrative apparatus for precisely these tasks.

EEG and EEG surcharge

The Renewable Energy Sources Act, EEG 2017 or “the German law for the expansion of renewable energies”, regulates the preferred feed-in of electricity from renewable sources into the power grid and guarantees their producers fixed feed-in tariffs. The EEG lists the forms of alternative energy generation eligible for funding and how the electricity may be used. It stipulates that network operators are obliged to purchase the electricity. In addition, the EEG surcharge paid by the end user ensures a fair balance of advantages and disadvantages on the part of the operator. The EEG and the EEG surcharge also regulate how to proceed if the operator wants to use some or all of the electricity himself. For the operator of a very small photovoltaic system, the consumption of self-generated electricity can be more expensive than selling it and covering his own needs from the commercial power grid. The law also exempts the railways and large companies from the regulations of this levy in order not to jeopardize their competitiveness through the soaring electricity costs.

Biofuel Quota Act

The Biofuel Quota Act of 2006 states that by 2020 at least 10 percent of all fuel that is required must consist of sustainable resources. The gradual transition to this quota is also regulated by law. Since 2007, the proportion of biologically produced fuels has to increase annually by 0.25 percent to an ideal value of eight percent. This law does not regulate how oil companies proceed. In 2015 the BioKraftQuG was changed. From 2015 the so-called decarbonisation strategy of the European Union will be implemented in Germany and the biofuel quota will be replaced by a general greenhouse gas saving target of 6.25 percent. The total quotas for biofuels that had previously been in force will be abolished. The minimum requirement for a biofuel with regard to its greenhouse gas saving potential compared to conventional fuels is specified by the Biofuel Sustainability Ordinance (BiokraftNachV). According to the ordinance, this minimum requirement is to be increased from the current 35 percent to 50 percent on January 1, 2017 and to 60 percent from January 1, 2018.

High time for the energy transition

Innovative processes for alternative energy generation are becoming increasingly efficient, so that the production of fossil fuels is relieved considerably. This is also an important step since raw materials such as coal, uranium, oil or gas are not infinitely available. According to scientists, uranium, the main resource for nuclear power plants, is only sufficient for about 200 years. Furthermore, as the quantity dwindles, conventional conveying methods become uneconomical. In addition, more and more energy is required in many areas. It is therefore essential to break new ground and develop other alternative energy sources. Primary sources such as sun, wind and water already make a significant contribution to the environmentally friendly generation of energy. Other processes are mostly CO2-neutral, which leads to an improvement in the climate balance.

A look into the future reveals that there is a big branch going in the direction of biochemistry. Fuel from algae, hydrogen from bacteria or osmosis power plants at river mouths should enable even more efficient methods of energy generation. In addition, new types of generators with significantly higher efficiency are being developed. There are many approaches to improving the climate balance, but the idea is always the same: to distance oneself from depleted deposits and to focus on alternative energy generation.

A contribution by:

  • Silvia chicken

    Silvia Hühn is a freelance editor with a technical focus. Among other things, she writes about the records in the world.

Vacancies in the field of energy & environment