Importance of Energy & Distributed Energy Systems
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Importance of Energy
We are about to start a rather long set of posts on energy and especially harvesting or generating it in decentralised manner with various ways to store it to be used when energy resources are not available (for example in winter when solar panels do not produce).
Why will we devote so much space to handling different ways of generating, storing and using energy in distributed way?
Leslie White argued in the 1940’s that the amount of energy harnessed and used by a society is a fundamental factor in determining its level of cultural complexity. According to White, societies that harness more energy are capable of creating more complex and advanced cultures.
This seems intuitively right. The more there is energy to use, the more we can automate and have robots and computers do non-creative work for us. This releases time to pursue other interests like research and development of technology and creation of arts. This work in turn produces more efficient ways of harnessing and utilizing energy, turning development into a positive feedback loop.
In very simple terms culture can be seen as a thermodynamic system.
This is captured in White’s law that states "culture evolves as the amount of energy harnessed per capita per year is increased, or as the efficiency of the instrumental means of putting the energy to work is increased".
White differentiated in his work in the 1940s five stages of development. First use of own muscles, then domestication of animals, third agricultural revolutions (using the energy of plants), then use of natural resources (coal, oil, gas) and finally nuclear energy.
Distributed Energy Systems
In the following small set of posts, we’ll look at different technologies for generating energy in distributed manner. In earlier two-part segment we looked at how the introduction of distribution and intermittent energy sources is going to change the nature of the electricity distribution. (Energy Industry Structure and Chaos Grid).
In distributed energy systems the energy production and consumption are close by. Heat and electricity is primarily generated for own use and surplus sold to the grid (electric grid or district heating network). They utilise renewable energy sources and rely on small-scale energy systems. This can mean solar cells, wind turbines, combined heat and power generation, ground source heat pumps, biofuel boilers, hydropower. On larger, regional level this may mean small modular nuclear (SMR) reactors or geothermal power. Both can be used for heat and electricity.
They have some obvious benefits such as smaller transfer losses, local jobs, better supply security and lower carbon emissions.
Distribution is done by a micro-grid, which is a geographically restricted area containing and controlling generation units, storage and consumption. They can be connected to the national grid for selling excess energy but critically also work in island mode (unconnected to grid) should there be disturbances in national distribution networks. (Microgrids term is used for smaller installation, minigrids for slightly bigger powering larger places like whole factory or small island, here we talk with term microgrid).
Usually, microgrids are only for electricity but sometimes also for heat distribution. Several microgrid can be connected together to provide more complex topologies. This improves stability of the interconnected systems and also allows participants in different microgrids to sell and buy their capacity to each other via local energy markets.
Several of the energy generation methods mentioned above are intermittent. They only work for part of the time and can fast stop producing for example when wind stops blowing. There is also large seasonal variation. Hence there is a big need for storing energy so that it can be later retrieved. Storage systems will follow this fleet of post.
So lets dive in to the wonderful world of local energy generation methods.
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