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Is it time to ask UKPN to consider if HVDC works better in future networks ?

Helios
I have been wondering about the big line losses that are necessary in HV transmission systems , HVDC can nearly halve these to 4% but all the new renewable technology of generation and of storage is mostly DC . From the interconnector its all AC cant really change that , but if the electric car becomes reality then all the chargers will be converting DC to AC (in some quite high flows of electricity from low to full of some batteries) , so we are perhaps saying that the electric car will bring more line losses , it might not be that bigger deal, but if we electrolyse water to Hydrogen and Oxygen then the conversion losses from AC to DC will add up , so it has to be better to just transmit in DC , if we could generate in DC and I think we have brushless three phase generators now then we generate and transmit efficiently to the new big users of electricity . In the USA we see generation plant to city interconnector , I don't think they use a balancing grid , as cities are so far apart . I know any design has its problems but with the new uses of electricity any generation system will have to match (or think about the new denands) , its perfrectly possible to have designed and balanced generator to interconnector supply , but a shared transmission grid obviously allows you to arrange supply generator and demands in a different way .

One use I thought about is for a village to say have a battery and the line to it may only charge the battery once a week as DD line to DC battery and that electricity that is then spare can be used to say make Hydrogen ? It could give a completely different and more efficienct system ? Not really worked much on HV systems , but I can sort see a sketch of how it could work as a network . If only a short distance to a big demand then might as well use AC , but a 1000mw supply to an interconnector losing 7% over its life time is a lot .
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    Hi Simon , yes it would cost quite a lot of money , but it might pay for itself from the energy gains/ losses , 4% in MW terms is a bi deal , I think UK peaks and lows are about 20,000MW to 45,000MW , so that's something like 800 to 1600MW every hr , which is pretty much like a new power station , thrown in for free.

    The energy use problem of efficiently generating power and low carbon thinking, wind and hydro are mostly in DC ,as is energy store in batteries (car or Grid scale), and water electrolysis are all DC systems and surely its best to optimise in DC before inversion into AC. We do have pretty efficient transformers and DC requires rectification and only relatively recently has the engineering made HVDC systems possible , siemens I think has managed 1000kv DC , but that was for a super hydro project .I think they use 400KV DC in the EU , so they must have efficient rectification devices, and I guess the cooled superconductor is pretty near (were at -60oC) so we really could have a system with much lower transmission losses, but as you say not much we can do past the interconnector as most domestic and business use is for AC . That's what worries about me about the car chargers being planned they are all  Dc to car battery but AC in feeds , so putting one in every house will add up ,, one calculation I saw put at least a 20% in crease  on MW required for the electric car to replace fossil fuels , so we really going to need an efficient transmission system sooner or later .
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    Hi Simon , yes it would cost quite a lot of money , but it might pay for itself from the energy gains/ losses , 4% in MW terms is a bi deal , I think UK peaks and lows are about 20,000MW to 45,000MW , so that's something like 800 to 1600MW every hr , which is pretty much like a new power station , thrown in for free.

    The energy use problem of efficiently generating power and low carbon thinking, wind and hydro are mostly in DC ,as is energy store in batteries (car or Grid scale), and water electrolysis are all DC systems and surely its best to optimise in DC before inversion into AC. We do have pretty efficient transformers and DC requires rectification and only relatively recently has the engineering made HVDC systems possible , siemens I think has managed 1000kv DC , but that was for a super hydro project .I think they use 400KV DC in the EU , so they must have efficient rectification devices, and I guess the cooled superconductor is pretty near (were at -60oC) so we really could have a system with much lower transmission losses, but as you say not much we can do past the interconnector as most domestic and business use is for AC . That's what worries about me about the car chargers being planned they are all  Dc to car battery but AC in feeds , so putting one in every house will add up ,, one calculation I saw put at least a 20% in crease  on MW required for the electric car to replace fossil fuels , so we really going to need an efficient transmission system sooner or later .
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