Central vs. Decentral Energy

A centralized system is the traditional power generation, transmission and consumption system that transfers high amounts of power in MW/GW from a Thermal or Nuclear power station to the consumer that is located far away from the generation plant. So, Power is generated at one place and distributed to different places by overhead power transmission lines.

Centralized Power system

[Figure 2: Centralized power system] [2]

A decentralized system is a system where sources are located near to the loads and generation sources produce small amounts of power in kW/MW. Decentralize sources like Photovoltaics PV panels, Wind turbines are commonly used nowadays.

Decentralized Power system

[Figure 3: Decentralized power system] [2]

The criteria for the comparison of Centralized vs Decentralized systems are presented below. They involve economies of scale studies and consider the most cost-effective system [3]

  1. Economies of scale: the advent of centralized systems like steam turbines made it possible to increase the size of the turbines while decreasing the marginal cost of electricity production. Decentralized systems are more expensive and require higher costs for maintenance.

  2. Energy efficiency: Centralized systems achieve higher efficencies through larger facilities than Decentralized systems if you compare them by their use of primary energy and the generated energy.

  3. Innovation in electricity transmission: Alternating current is usually used to transmit electricity over long distances without a significant loss or reduction. For decentralized systems we can use DC and AC transmission to easily transmit power in short range.

  4. Reliability: to increase the reliability at the customer’s end, large electricity production facilities were connected to the transmission networks, but if a damage in the main transmission line occurs, it leads to power outage. Whereas in decentralized systems, user get the power from various generation sources, so power outage problems are negligible.

  5. Environmental constraints: the use of transmission networks made it possible to relocate the generation facilities outside the city centers thus removing pollution due to exhaust from coal fire plants. Clearly,the way how centralized power plants produce energy destroys the environment in many ways. The climate suffers through the exponential increase of CO2-pollution. Moreover complete areas all over the world are ruined through the mining and fracking of ressources. In decentralized systems, mostly renewable power generation sources are used which are way more environmental friendly (no emissions, no waste, no exhaust gases, no need of ressources) than traditional power generation by centralized systems.

Photovoltaic

As the solar box uses photovoltaic energy we take a closer look at it: Photovoltaic has a long history. It began in 1839 with observations carried out by Edmond Becquerel. Becquerel observed that if two platinum electrodes are placed in solution and exposed to sunlight, electric current flows. This effect was very small and had no practical significance at that time, yet it remained unforgotten. Moreover, this effect was not understood until Einstein delivered the explanation of the photoelectric effect and quantum nature of light in his well-known paper from 1904. But even then this effect remained for a long time an interesting physical phenomenon but without practical meaning. A working solar cell was only realised after semiconductor technology had evolved. In particular, the availability of high-purity crystalised silicon was an important prerequisite. Even today silicon remains by far the most important material for solar cell production. The first silicon solar cell was created in 1954 in the Bell Laboratories in Murray Hill, United States, by the scientists Chapin, Fuller and Pearson. Even back then solar cells were able to achieve an efficiency of 6 per cent, which was soon increased to 10 per cent. [1]

Stand-alone PV-systems

It is a PV system that has a battery to store the extra energy.

Advantage: Can put this excess electricity in batteries. Storing the extra energy, which allows self-supply with electrical energy. So you can use it perfectly in remote locations / rural areas with no grid connection.

Disadvantages: Extra costs, energy storage typically comes with losses. In the Figure below you can see an example of a system.

Energy system

[Figure 3 - Stand-alone PV-systems] [1]

Stand-alone hybrid systems

Since batteries can only store a limited amount of energy, it is possible to use a backup generator (i.e. diesel), if the weather conditions prevent the PV or wind generators from generating energy

The Figure below shows an example of a stand-alone hybrid system.

Energy system

[Figure 4 - Stand-alone hybrid systems] [1]

Grid connected PV-systems

Grid connected PV-systems are directly connected to the utility power grid.

Advantages: They are generally cheaper and simpler to install.

Disadvantages: The energy supply depends on the grid and the power transmission infrastructure.

The Figure below shows an example of a stand-alone hybrid system.

Energy system

[Figure 5 - Grid connected PV-systems] [1]

References

[2] https://grist.org/renewable-energy/2011-11-28-americas-energy-future-ipads-v-typewriters-with-guns/

[3] Centralized and Distributed Generated Power Systems - A Comparison Approach Future Grid Initiative, Power Systems Engineering Research Center Empowering Minds to Engineer the Future Electric Energy System, June 2012. https://pserc.wisc.edu/documents/publications/papers/fgwhitepapers/Momoh_Future_Grid_White_Paper_Gen_Analysis_June_2012.pdf