Power grid of tomorrow
Thursday, 1 July 2010
S.A.Mansoor
About seventy years back, electric power in our part of the world meant a few light bulbs and fans. Electric iron, air conditioners, microwave oven and refrigerators, the common household articles today, were unheard-of in those days.
Today, thanks to the electric power grid, we take all these for granted. It is when power is not there we come to realise what we miss, and how much we need it, and cannot live without it. However, thanks to another electrical gadgets -- IPS and batteries -- the misery, particularly in hot days, is somewhat contained by instant home back-up power.
In Bangladesh, we are all familiar with the terms 'load shedding' and also 'power rationing' like food grain, cooking oils, salt and sugar; which were rationed in the days of the last 'World War' that ended in mid 1940s.
The power grid, silent and mute, hanging overhead or sometimes lying underground, is providing us instant electricity generated from far away. Here power generation, an electro-mechanical activity, has its own noise, heat, smoke and soot; very much like any industrial factory!
However, the grid of tomorrow will have features for the power users, unthinkable to us now in Bangladesh! These power grids will be able to handle 'alternative power sources', which have variations in output, depending on the sun or wind. It will even out these fluctuations of power inputs, with networking interconnection between various centres of power production and the all-spanning grid.
Power grids span continents; and in the coming days the European Grid network will expand to Africa, and tap on to the vast potential of solar energy generation from the Sahara Desert; which could well be world's largest sun and wind combined alternative energy green power producing zone! The US power grid, sometimes called as the "World's Biggest Combined Machine" easily carries around a million megawatt of power.
For power transmission on the grid, high or even ultra-high voltage is a must to contain power losses for the large distances that are involved.
For this we use AC (alternating current); as it can be easily stepped up for transmission and then, subsequently reduced to normal household and industrial power voltage range, as needed at the location where it is to be used, connected locally to the low voltage power supply lines.
However, these days, for transmission of bulk power across very long distances DC (direct current) is sometimes preferred over AC.
We can have power storage. The surplus power produced at late at night and dawn, when lighting and air-conditioning loads usually are lower, can be fed back to the system at the time of maximum demand, from sundown to midnight.
This power storage can be of two main types. These are a) Compressed Air Storage and b) Pumped Hydropower Storage. For compressed air storage, during low demand periods, large air compressors compress and store air in storage tanks. During maximum demand period; the stored compressed air drives turbo-alternators (like steam driven turbine generators) producing the extra power needed. For the storage hydropower set-up, we build an artificial closed cycle hydro power plant. Water from a dedicated reservoir at the ground level, is pumped up to a dedicated water reservoir, set at a higher elevation and stored there when power demand is low. During high power demand periods, water from the reservoir flows though water turbines producing electric power! The exhaust water from the water-turbine flows down to the storage area at the lower level by gravity; to be later pumped up, when power demand is low.
Of the two ideas, the hydo-power option in Bangladesh might not be feasible, because of the two large water reservoirs at both low and higher levels that are needed, which can not be located far away. Also the area needed for this, is much larger, than the other option. The compressed air option is more feasible for us, more so if we have underground air storage tanks so that space requirement is reduced.
However, even with overhead air storage, the space needed is possibly no more than a space of a conventional power plant of today.
Our grid management today, despite computer data recording and its internet transmission, is still people dependent to a large extent. Only advantage is that information of status is easily available, which was earlier totally dependent on our fragile telecommunication system.
Emphasis today is on faster response times than humanly possible. Here automated sensors and sensor related switching and transfer of power in bulk is managed through interactions between inter-related grid systems. This is practically an instantaneous response, automatically based on constant monitoring of load densities and patterns with the time duration limited to a few cycles of alternating current.
Tomorrow's grid will control large power centres' demand trends and the inputs from 'alternative sources' of 'green power' that can be very useful for this type of automated grid management.
Grids have not yet been developed to meet the challenges of alternative energy sources on a large scale. The need for a 'smart' and reactive grid is imperative for large concentration of alternative energy sources, even larger than any conventionally fueled power plants. For us in Bangladesh, we must look into this matter, and keep updated so that hopefully 'smart grids' are in operation here towards the later part of this century.
(An engineer, the writer is Technical Adviser of Spectra Group)
About seventy years back, electric power in our part of the world meant a few light bulbs and fans. Electric iron, air conditioners, microwave oven and refrigerators, the common household articles today, were unheard-of in those days.
Today, thanks to the electric power grid, we take all these for granted. It is when power is not there we come to realise what we miss, and how much we need it, and cannot live without it. However, thanks to another electrical gadgets -- IPS and batteries -- the misery, particularly in hot days, is somewhat contained by instant home back-up power.
In Bangladesh, we are all familiar with the terms 'load shedding' and also 'power rationing' like food grain, cooking oils, salt and sugar; which were rationed in the days of the last 'World War' that ended in mid 1940s.
The power grid, silent and mute, hanging overhead or sometimes lying underground, is providing us instant electricity generated from far away. Here power generation, an electro-mechanical activity, has its own noise, heat, smoke and soot; very much like any industrial factory!
However, the grid of tomorrow will have features for the power users, unthinkable to us now in Bangladesh! These power grids will be able to handle 'alternative power sources', which have variations in output, depending on the sun or wind. It will even out these fluctuations of power inputs, with networking interconnection between various centres of power production and the all-spanning grid.
Power grids span continents; and in the coming days the European Grid network will expand to Africa, and tap on to the vast potential of solar energy generation from the Sahara Desert; which could well be world's largest sun and wind combined alternative energy green power producing zone! The US power grid, sometimes called as the "World's Biggest Combined Machine" easily carries around a million megawatt of power.
For power transmission on the grid, high or even ultra-high voltage is a must to contain power losses for the large distances that are involved.
For this we use AC (alternating current); as it can be easily stepped up for transmission and then, subsequently reduced to normal household and industrial power voltage range, as needed at the location where it is to be used, connected locally to the low voltage power supply lines.
However, these days, for transmission of bulk power across very long distances DC (direct current) is sometimes preferred over AC.
We can have power storage. The surplus power produced at late at night and dawn, when lighting and air-conditioning loads usually are lower, can be fed back to the system at the time of maximum demand, from sundown to midnight.
This power storage can be of two main types. These are a) Compressed Air Storage and b) Pumped Hydropower Storage. For compressed air storage, during low demand periods, large air compressors compress and store air in storage tanks. During maximum demand period; the stored compressed air drives turbo-alternators (like steam driven turbine generators) producing the extra power needed. For the storage hydropower set-up, we build an artificial closed cycle hydro power plant. Water from a dedicated reservoir at the ground level, is pumped up to a dedicated water reservoir, set at a higher elevation and stored there when power demand is low. During high power demand periods, water from the reservoir flows though water turbines producing electric power! The exhaust water from the water-turbine flows down to the storage area at the lower level by gravity; to be later pumped up, when power demand is low.
Of the two ideas, the hydo-power option in Bangladesh might not be feasible, because of the two large water reservoirs at both low and higher levels that are needed, which can not be located far away. Also the area needed for this, is much larger, than the other option. The compressed air option is more feasible for us, more so if we have underground air storage tanks so that space requirement is reduced.
However, even with overhead air storage, the space needed is possibly no more than a space of a conventional power plant of today.
Our grid management today, despite computer data recording and its internet transmission, is still people dependent to a large extent. Only advantage is that information of status is easily available, which was earlier totally dependent on our fragile telecommunication system.
Emphasis today is on faster response times than humanly possible. Here automated sensors and sensor related switching and transfer of power in bulk is managed through interactions between inter-related grid systems. This is practically an instantaneous response, automatically based on constant monitoring of load densities and patterns with the time duration limited to a few cycles of alternating current.
Tomorrow's grid will control large power centres' demand trends and the inputs from 'alternative sources' of 'green power' that can be very useful for this type of automated grid management.
Grids have not yet been developed to meet the challenges of alternative energy sources on a large scale. The need for a 'smart' and reactive grid is imperative for large concentration of alternative energy sources, even larger than any conventionally fueled power plants. For us in Bangladesh, we must look into this matter, and keep updated so that hopefully 'smart grids' are in operation here towards the later part of this century.
(An engineer, the writer is Technical Adviser of Spectra Group)