Managing the National Grid, Fluctuating Supplies, Seasons & Storage
There are a number of technical challenges in providing and storing electricity supplies from intermittent sources such as renewable supplies. Solar supplies are generated in variance with time of day, season and cloud cover. Wind and hydro supplies can vary enormously by the day. Wave and tidal are generally more predictable but still have daily tidal variance. Continuous feed in anaerobic digestion can provide a steady supply, but this energy generation is more efficient at producing methane for vehicle fuel.
The Sustainable Development Commission while postulating an overall reduction in energy use of at least 30% by 2050 nevertheless forecast an increase in electricity consumption of 16% due to expectations of changes such as diesel trains and road transport switching over to electric vehicles. This has major implications for the Grid.
Local short-term fluctuations (SLEW) can be accommodated by the Grid provided there are sufficient back-up reserves on-line e.g. pumped up storage, emergency generators, quick response gas turbines etc. We need to be able to store energy off grid, which then feeds back into the grid to meet demand. Electric cars are being considered as a useful multiple system of storing electricity which can be left plugged in when idle, drawn on as needed by the grid and used for travel when energy supplies permit.
Water pumping systems can be used, whereby excess electricity is used to pump water up a height to store energy, to be released with the energy recaptured by turbines feeding back into the grid as needed. The large water reservoir at Roadford (which currently supplies Totnes and District) could be part of a regional energy storage scheme. Smaller schemes in conjunction with weirs and turbines on some of the smaller local rivers (e.g. near Sharpham) could also be utilised. In Spain desalination plants are used to store energy.
At the supplier level it is generally most convenient to be able to plug into and feed or use from the national grid using either 2 separate meters or just one 2-way meter (as in Oregan for the last 20 years!). Government set feed-in tariffs for consumer produced power supplies are famously ungenerous to smaller suppliers, however these are set to improve.
The national grid needs to be able to match demand with supply, there are a number of ways that this can be achieved, for example ‘smart metering’ to encourage customers to use ‘off peak’ electricity at cheaper rates. Smart metering can be used to manage both electricity and gas supplies; power companies can:
- Vary the price according to hour by hour supply and demand
- Monitor usage remotely (no need to read meters manually)
- Provide users/consumers with an easy to understand indication of energy usage
- Access customers’ appliances switch them on and off remotely (this will require modifications to the wiring in individual premises) to reduce loads (peak-lopping)
A maximum allowance or consumer ration can be set. On the Island of Eigg, households have a warning noise when they are reaching their maximum allowance for the day (if they exceed this the electricity cuts out and they are fined).
We need to question whether we can practically or realistically expect the electricity supply to be available 100% of the time on the national grid. It will be easier for us to get through the coming energy transition if we can accept and prepare for some interruptions in supply. There is an ongoing debate at the time of writing that there could be an upper limit to the amount of renewable energy supplies the National Grid could accommodate, however experience from Germany suggests 100% is possible. A renewables based grid will be easier to put in place if we can accept some management of demand, including short interruptions in supply.
Resilience in the national grid at the local level poses many challenges; however there is speculation that resilience could be achieved by creating regional grids linked nationally using interconnectors (as currently used between countries). There is a need for research and trials in grid management for renewable supplies and storage.
Some properties of storage systems and fuels: Energy density versus efficiency (Source Sustainable Energy Without the Hot Air)
4 comments on “Managing the National Grid, Fluctuating Supplies, Seasons & Storage”
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Oregan
Oregon
thanks for pointing this out.
I am new to research in “Transition” ideas, but this project is very interesting to me. I think it is a nice first couple steps in the right direction, however I would be very concerned about several ideas presented here. I understand that sometimes a conceptual ideal of a centrally planned system seems nice but I argue that anyone promoting resilience must begin with self-reliance and individual freedom instead.
Any interconnected system could be described as a chain, and any chain is only as strong as its weakest link. Instead of “covering weaknesses” by requiring seeing outages as commonplace, lets strengthen each link of the chain. In other words, if every County is a net positive producer of electricity, then there is no need for a National control grid or outages. In the same way, every County should be strengthened by the citizens. If every District or indeed every home is a net positive producer, it strengthens the County and the Nation.
Also, there seem to be many conflicting ideas presented, although understandably they are presented as possibilities and not a finished product. For example, the Island of Eigg or the part on “electric cars …which can be left plugged in when idle, drawn on as needed by the grid and used for travel when energy supplies permit.” seem to indicate electricity distributed by a government and not paid for by the consumer. It seems ridiculous that if the electricity is rationed and automatically cuts off that a person would be fined also. Fining a person for useing their allotment of electricity is tantamount to terrorism, making a person afraid to use what should be “their share.” If on the other hand consumers are purchasing that electricity and charging their vehicles with it, it boggles the mind what system would be able to track every battery plugged in nation-wide and then legalize the theft of individual property, possibly then leaving the vehicles owner without means of transportation?
This idea of electricity being provided by a central authority, which can “Access customers’ appliances switch them on and off remotely” or can set an arbitrary daily allowance is a terribly scary idea and goes against the very concept of resilience. Instead of centrally planned limits punishing those who go over their allowance, lets promote strategies that increase individual production, decrease energy loss, and increase individual resilience:
-Tax breaks for home/business solar/wind generation or locally organized “bulk purchases” of these items to get better deals.
-High capacity batteries for homes that use the “smart grid” to purchase energy when cheapest and store perhaps a months worth of electricity.
Hi Tyler, Your extended response is interesting. As you say, the ideas muted in the Timelines are possibilities and within current knowledge and technical developments to date. With pressure on new measures to provide energy as electricity and how to manage supplies and the grid etc., I’m sure there will be many new options coming forward over the period of the EDAP. Hopefully our dialogue will have stimulated some, thinking and understanding around this really urgent debate.