What are alternative energies? This question usually means other energy sources than those previously used. Instead of the previous, limited and environmentally polluting energy sources, one would like to use sustainable energy sources that are not limited in time and are more environmentally friendly.
We will see, however, that replacing conventional energy sources with alternatives is not just about the sources of our energy, but inevitably requires thinking about the type of storage, transport and use. So it's not just about feeding electricity into the current grid from another source or obtaining the fuel for an internal combustion engine in a different way. The thought that you exchange the sources and otherwise the systems could stay as they are is deceptive. Because energy sources and uses are inevitably related to one another. Our technologies today have resulted in exactly the systems that we currently find. They are adapted to each other.
Today's energy carriers for transport are mainly diesel, gasoline and kerosene. The energy sources for industry and households are the power grid, district heating and natural gas. And where does this energy come from originally, what are the sources for it? Nowadays, this energy is mainly obtained from fossil materials. These are in particular oil, natural gas and coal. In addition, radioactive uranium also plays a role in electricity generation, which can also be counted among the conventional energy sources. None of them represent a sustainable solution.
The fossil fuels contain carbon (C), which was withdrawn from the atmosphere during geological development and deposited in the earth. Plants living at the time had withdrawn CO2 from the primeval atmosphere, but were then buried under layers of earth and strongly compressed. For the atmosphere, it doesn't really matter in what form the CO2 is bound and thus withdrawn from it.
In an unrealistic way, one could imagine as a mental game that to the extent that the previously bound CO2 was released, new plants would be grown in addition to the existing plants so that the CO2 released by the combustion is bound by them, the process that is, it would be CO2-neutralized. In practice, of course, that is not possible. And nowadays, through clearing and devastation, more vegetable matter is broken down than increased. Incidentally, the algae in the sea also play a major role for our planet, and their mass and thus overall influence is very large. But even here you can't just increase the algae mass at will.
When fossil fuels are burned, CO2 is introduced into the atmosphere, which of course changes the composition of the atmosphere. Due to the increased CO2 content, the so-called greenhouse effect arises, in which insufficient heat radiation can no longer leave the earth and heat can be released into space. This is a major contributor to global warming.
In addition to the greenhouse effect, there is another major disadvantage that fossil fuels have for us: their supply is limited. In the foreseeable future, there won't be enough of it to meet people's needs. So there are already two conditions that an alternative should meet: The climate behavior should be neutral and the supplies should be unlimited. That sounds utopian.
The shortage of supplies also applies to uranium. Because when considering energy sources, it must of course be taken into account that the entire human race has to be supplied, not just a small minority with certain shares. So if you look at the total needs of people, we have a resource problem similar to that of fossil fuels. In addition, nuclear power plants do not pollute the atmosphere with CO2, but with radioactivity. It is irrelevant whether the incidents become known or not. Unknown incidents, such as the leukemia cases in the march near Hamburg, testify to the pollution of our environment as well as officially known accidents in nuclear power plants. In addition to the shortage and the clandestine and official contamination, there is the problem of final storage with nuclear power. To many people it seems doubtful whether storage in the earth will still be seen as unproblematic by future generations in a thousand years as it is by today's experts, who have long since enjoyed their retirement. The transport and handling of the radioactive substances and the contaminated material inherently carries the risk of contamination of the environment at any time.
All alternative energy sources are ultimately due to the radiation of the sun, the warmth of the earth's core or the rotation of our planet. In other words, sources that were created when our solar system was formed (see also Wikipedia: Renewable_Energies).
In addition, attempts are still being made today to use nuclear fusion as a controlled process. So this would represent a kind of self-made mini-sun. But apart from the fact that the practical use does not seem to be within reach, one will also have to deal with radioactive waste here. For the generations living today and in the near future, nuclear fusion will probably not be able to make a meaningful contribution.
The earth's core enables us to use geothermal energy. Ultimately, the sun provides us with the following energy sources:
- Solar radiation for photovoltaics
- Solar radiation as solar heat
- Wind power
Geothermal energy occurs in different forms. Geysers and hot springs can be used as well as the warmth of the earth's interior that is everywhere in Central Europe. Geothermal energy is used to heat liquids. From a depth of approx. 10 m, the temperature is invariably around 14 degrees Celsius throughout the year, and from 1 to 2 meters it is 5 degrees Celsius. The temperature increases with increasing depth by approx. 28-40 degrees per 1000m. That doesn't sound like much, but you have to consider that geothermal energy, for example, in contrast to a piece of coal that burns hot for a short time, is practically infinite. So you can heat any amount of water to this temperature. However, additional energy still has to be supplied in order to operate the compressor. Geothermal energy in this form is therefore not a stand-alone solution. However, the energy savings are immense. The function corresponds to an inverted refrigerator. The compressor only has to do relatively little work to heat the water to the required temperature. The holes are usually up to 100m deep. However, there are many different solutions. It is estimated that the earth is 2.5 times that of mankind. radiates the required amount of energy into space.
Photovoltaics generate electrical voltage that can be fed into a power grid as electricity or, for example, used for the production of hydrogen by means of electrolysis.
Solar heat can be used to provide hot water. Or provide electricity indirectly by heating water and the turbines operated by it. Wind power can also be generated from solar heat, which is used in updraft power plants to operate generators. The electricity can be fed into a power grid or, for example, can also be used to produce hydrogen.
Wind power also generates electricity that is transported away via a power grid or can be used on site to produce hydrogen. Mechanical water pumps, for example, can also be operated directly.
Biomass is produced by plants or animals. It can be used for the direct production of hydrogen. Biogas can also be produced in which hydrogen does not play the decisive role. Biogas contains 50-75% methane (CH4), alongside essentially CO2, steam, ammonia, hydrogen sulfide and oxygen. It can be obtained from proteins, fats and carbohydrates. The starting materials range from straw and kitchen waste to liquid manure, which is used for anaerobic digestion. Biomass are also fuel in the form of vegetable oil or wood as fuel.
Hydropower, like the other forms, is ultimately converted solar energy. Generators generate electricity that is fed into a power grid or can be used to produce hydrogen. Hydropower exists in the form of gradients in rivers, waves, tidal and ocean currents.
Hydrogen is not a source of energy. It's just the carrier. If, for example, the primary energy solar radiation has been converted into the secondary energy electricity, this energy can be stored in the form of hydrogen. This also happens with the gasification of biomass. Hydrogen is used to store and transport the secondary energy.
Hydrogen itself is free of carbon, which means that almost only water vapor is produced when it is used. This is an important difference to e.g. methanol, with which many fuel cells already work today. Contrary to popular belief, there is not only the option of hydrolysis by means of electrical current for the production of hydrogen. Another possibility is the gasification of biomass or fossil fuels. The big advantage here is that CO2 is concentrated in one place. This opens up the possibility of reusing the CO2 instead of releasing it into the atmosphere. The gasification of biomass from agriculture naturally only produces as much CO2 as was previously absorbed by the plants. Seen in this way, the process would already be CO2-neutral. Another possibility for the production of H2 are, for example, certain types of algae that emit hydrogen directly.
The advantage of using hydrogen lies in its importance for renewable energy sources. Using hydrogen as a storage medium, the time differences between the fluctuating amount in energy production and the actual energy demand can be compensated for. The energy generated by different strong winds or solar radiation is therefore available exactly when it is needed most.
To store hydrogen, it can be liquefied by freezing (LH2, liquid H2) or compressed (GH2). Processes are also being worked on to bind hydrogen to metals for storage.
Storage of CO2
For at least 650 million years, the CO2 content of the atmosphere has not been as high as it is caused by mankind today. The previous CO2 level was consistently below 300 ppm (parts per million). If this development is extrapolated over the next 50 years, the effects can no longer be foreseen. It is therefore quite clear that mankind (1) firstly has to operate an energy industry that is sustainable and climate-friendly, (2) secondly has to remove CO2 from the atmosphere and (3) thirdly, it is very likely that further measures against the greenhouse effect, which does not end immediately must be undertaken.
It is therefore foreseeable that future CO2-neutral behavior will no longer be sufficient to ensure the continued existence and quality of life of most people, since developments cannot be stopped or reversed without delay. How fatal, then, is the ignorance of the public consciousness and decision-makers about this problem. How fatalistic does the future seem when you see how far we are from the first point. Scientists are already working on scenarios in which, for example, balloons or rockets filled with sulfur are brought into the higher layers of the atmosphere in order to intercept the solar radiation in these layers in the form of a layer of particles. In a weakened form, however, just as after a large volcanic eruption, after a devastating meteorite impact or the so-called nuclear winter. And these scenarios are not fantasies of unrealistic spinners, but result from the fact that certain scientists put their intellectual horizons further than narrow-minded politicians, states or the limited public consciousness.
Hydrogen can also make a contribution to the second step, the removal of CO2 from the atmosphere. In the production of hydrogen from biomass, carbon dioxide is produced in concentrated form. Regardless of whether it is biomass from the living cycle or fossil fuels. Likewise, of course, the burning of fossil fuels already produces CO2. This CO2 can be captured and stored.
The CO2 carries carbon, which can later be used for the production of various materials through to the production of protein.
Solar hydrogen economy
The term solar hydrogen economy means that the entire handling of energy from its generation through storage and transport to its use is designed in accordance with the energy carrier hydrogen and its sustainable production. This means, among other things, the trend towards decentralization, which is why this development is not supported and thus suppressed by large corporations and other interests. For example, the natural gas network that is already in place in many places could be gradually converted into a hydrogen network by gradually increasing the amount of hydrogen that is already present. The suppression of development does not mean a conspiracy theory, but the anatomy of our energy industry that exists today does not allow us to go other ways than those which are consciously chosen by the energy companies or which are emphatically demanded by politics. Since there is no awareness and consensus about the imperative need for a solar hydrogen economy, it cannot develop. Here, too, the development does not seem to do justice to real needs.