[OpenTRV-interest] [OpenTRV-dev] Storage heating, dynamic demand, and OpenTRV

[Bjorn Graabek]

Like you, I have been surprised at the variability of my solar PV 
system. It can go from maximum power to less than half that and back up 
again just from clouds passing by.
In the past I thought that one of these days we could reach nirvana with 
renewable energy sources by having electrical cars making their 
batteries available for storing electricity for times when the renewable 
sources where not available. I've now had an electric car for a year and 
I no longer think that is a viable solution. I also don't think dynamic 
demand control in domestic homes is the way forward although some effort 
ought to be put into some sort of demand shifting so the peaks are no 
longer as high as they currently are.

I think the way forward is grid-sized batteries such as what AMBRI is 
working on http://www.ambri.com/
These types of batteries don't need to have the same kind of energy 
density that batteries for cars need as they won't be moved about. And 
with less energy dense batteries, hopefully cheaper batteries can be used.

Having said that, even lots of huge batteries are obviously not enough 
when we are talking about country-size energy needs and energy 
availability shifting.

Regards,
Bjorn

On 08/09/2014 11:33, Damon Hart-Davis wrote:
> One of the reasons that I feel slightly smug about my E- and W- facing arrays is that I at least smear my exports over a much longer period in summer!  %-|P
>
> Dynamic demand control I think can help a lot with intermittent sources, but it needs more thought.
>
> Rgds
>
> Damon
>
> PS. I wrote this some time ago, but things move on quickly: http://www.earth.org.uk/note-on-dynamic-demand-value.html
>
>
> On 8 Sep 2014, at 11:17, Mark Wigmore <EMAIL ADDRESS HIDDEN> wrote:
>
>> Your thought experiment does highlight a major issue with variable renewable energy sources. Having worked in wind energy it quickly became obvious that there needs to be suitable hardware between the generator and the grid for load balancing. The generating unit needs to appear to the grid as a source that can respond to demand fluctuations. Off grid systems normally require banks of batteries, which seems to be sensible for grid-connected systems also. Otherwise in the middle of the day all the south-facing PV arrays are generating loads of power that's just not required!
>>
>> Mark
>>
>> On 8 September 2014 11:00, Damon Hart-Davis <EMAIL ADDRESS HIDDEN> wrote:
>> Hi,
>>
>> The key thing I’m aiming for here is short-term controllability to balance second-by-second flows in/out of the house, plus storage to carry that energy to a more useful time.
>>
>> Thus an electric storage heater rather than a normal one.
>>
>> Your DHW idea is in principle fine if done right, but storage in water isn’t plausible for everyone.
>>
>> Anyhow, only a thought experiment, so good to thrash it out!
>>
>> Rgds
>>
>> Damon
>>
>>
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