Comments on: VRB Power selected for one of DOE “smart grid” projects http://www.cleanbreak.ca/2008/04/25/vrb-power-selected-for-one-of-doe-smart-grid-projects/ Trends, happenings and innovations in the clean technology market Mon, 30 Jan 2012 14:28:54 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: Anonymous http://www.cleanbreak.ca/2008/04/25/vrb-power-selected-for-one-of-doe-smart-grid-projects/comment-page-1/#comment-1992 Anonymous Sat, 26 Apr 2008 02:43:00 +0000 http://www.cleanbreak.ca/2008/04/25/vrb-power-selected-for-one-of-doe-smart-grid-projects/#comment-1992 It appears to me that what they are doing is focusing on the losses in the feeder network - the low voltage lines (5-25 kV) that carry the power from the substation to the customers neighborhood - where the transformers drop the voltage for delivery. This part of the network is responsible for a large part of the network losses becasue voltages are relatively low and currents are high. Becasue the loss is proportional to the square of the current, one can reduce losses significantly by reducing peak load - on that feeder. So by storing energy near the end of the feeder during low load periods and putting it back at peak, total loss will be reduced. I remain suspicious that this is not as good as it looks becasue the loss in storage devices is generally a lot worse than line loss (Overall system loss is generally less than 15% and I know of no storage system other than big hydro plants that are 85% or better..) I think that a better strategy is to get rid of the peaks by filling the valleys - and using the off peak energy to displace gas at the same locations - at the end of the feeders. The % line loss decreases as load factor improves and is minimized at constant load. It appears to me that what they are doing is focusing on the losses in the feeder network – the low voltage lines (5-25 kV) that carry the power from the substation to the customers neighborhood – where the transformers drop the voltage for delivery. This part of the network is responsible for a large part of the network losses becasue voltages are relatively low and currents are high. Becasue the loss is proportional to the square of the current, one can reduce losses significantly by reducing peak load – on that feeder. So by storing energy near the end of the feeder during low load periods and putting it back at peak, total loss will be reduced.

I remain suspicious that this is not as good as it looks becasue the loss in storage devices is generally a lot worse than line loss (Overall system loss is generally less than 15% and I know of no storage system other than big hydro plants that are 85% or better..) I think that a better strategy is to get rid of the peaks by filling the valleys – and using the off peak energy to displace gas at the same locations – at the end of the feeders. The % line loss decreases as load factor improves and is minimized at constant load.

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