[Greenbuilding] Swedish solar-heated village

Don Lush donlush at uniserve.com
Thu Nov 26 07:43:12 CST 2015


Thanks John (Daglish)- Could you help me on the interpretation of this interpret this data. 

For example when I look at the current data (8:30 EST) from Sondorborg it shows current insolation at 939 W/m2 (which I am assuming is the incident solar radiation energy currently hitting the earth's surface at this location??)
It then shows current solar production at 442 W/m2 (which I assume is supposed to be how much energy is being generated by the solar array per m2.) 
This implies a conversion efficiency of (442/939) 47% which is incredibly high! 
Other sites have zero insolation and negative production numbers implying that they are consuming power. 
How am I misreading this? 
 Don Lush 
Bolton Ontario

-----Original Message-----
From: Greenbuilding [mailto:greenbuilding-bounces at lists.bioenergylists.org] On Behalf Of John Daglish
Sent: November 26, 2015 6:58 AM
To: Green Building <greenbuilding at lists.bioenergylists.org>
Subject: Re: [Greenbuilding] Swedish solar-heated village

Our Dannish friends are way ahead...

Smart Energy Systems: 100% Renewable Energy at a National Level (Short Version) https://www.youtube.com/watch?v=S1P31EC0YsE

Smart Energy Systems: 100% Renewable Energy at a National Level (Full Version) https://www.youtube.com/watch?v=eiBiB4DaYOM

Solar heat fields for district heating   - real time production
statistics, not much today its cloudy
http://www.solvarmedata.dk/

regards

John Daglish
Paris, France




John Daglish
Paris, France


2015-11-25 21:11 GMT+01:00 Dan Johnson <danjoh99 at gmail.com>:
> It's great to see Nick Pine back on this list. I want to point out for 
> discussion that the electrical grid has virtually no storage! The grid 
> follows load and must be balanced nearly instantaneously with 
> dispatchable generation.
>
> Contributing PV energy to the grid is often part of the problem, 
> because renewables often need to be curtailed when production exceeds 
> demand. Grid operators can't taper down the baseload generators every 
> time the wind picks up. The California ISO site has a lot of current 
> information and I've found it a great place to learn about the 
> electrical grid. And this is one of the most progressive operators in 
> terms of their renewables and storage mandates from the State. 
> http://www.caiso.com/Pages/default.aspx
>
> Bringing this back to solar storage in winter (in California, for 
> example), when I do morning warm-up or heat during a cloudy day using 
> my electric heat-pump, the electric grid is running natural-gas-fired 
> generators at an emissions rate that is dirtier than average. This is 
> because renewables are generally not online during these periods. 
> Check out this net-demand chart from Cal ISO: the morning peak of the 
> green line is all fossil fuel, before solar comes online. 
> http://content.caiso.com/outlook/SP/duck.gif. There may be less 
> emissions and less fuel burned if I just burned the natural gas at my 
> house with a condensing appliance, as a backup to my passive systems, using no storage. The chemical bonds in the natural gas provide the storage.
> :-)
>
> Any net surplus of PV from my house would occur when I don't need it 
> to power a heat-pump or A/C: these are periods when likely other 
> houses don't need it either. Net consumers would be commercial 
> buildings, hospitals, and other process loads on the grid. In one 
> scenario, we can ramp-down the fossil generators during these periods, 
> so **here is where we can argue that the homeowner's PV could be 
> considered a carbon offset**---but no more real than Terrapass. 
> http://www.terrapass.com/. In another scenario, the added power from 
> renewables just lets us bring more loads online---total load and demand grow over time! This is the opposite of what we wanted.
>
> Returning to grid-scale storage: it seems this is science fiction, 
> like clean coal. Euan Mearns has some great analysis of experimental 
> pumped hydro schemes in the Canary Islands.
> http://euanmearns.com/el-hierro-another-model-for-a-sustainable-energy-future/.
> California conducted a workshop in Jan 2014 on pumped storage and many 
> presentations from it are here:
> http://www.cpuc.ca.gov/PUC/energy/electric/Technical_Workshop_Understanding_Current_State_of_Pumped_Storage.htm.
> If 300 high reservoirs were built along the coast, using the ocean as 
> the low reservoir, the grid could get 572 GWh of storage, almost 1 day 
> of storage for California!
> http://www.cpuc.ca.gov/NR/rdonlyres/1521FE3B-2FB5-4A6A-A93B-45125D6EF8
> 95/0/Barnhart20140116CPUCPHSWorkshop.pdf
>
> Best,
> Dan Johnson
> Albany, CA
>
> On Tue, Nov 17, 2015 at 12:06 PM, Nick Pine <nick_pine at verizon.net> wrote:
>>
>> Kimmo writes:
>>
>>> I’m an entrepreneur that is doing research the possibility to use 
>>> some architecture ideas to heat houses in Sweden similar
>>
>> to what Soldiers Grove did back in 1979. We will of-course try to 
>> modernise the design but the basic concepts are the same with the 
>> “solar attic”.
>>
>> Soldier’s Grove attics required moving warm air down to the lower 
>> part of the building using fans or blowers and a motorized damper, 
>> and it’s hard to store solar heat from warm air. I figure cloudy days 
>> are like coin flips, so a building that can store enough heat for 1 
>> cloudy day can be at most 50% solar heated, with a possible max 
>> 1-2^-N solar heating fraction if it can store enough solar heat for N 
>> cloudy days in a row, eg 1-2^-5 = 0.97 with 5 days of storage. Most 
>> of the SG buildings were only 50% solar heated. Why stop there?
>>
>> It seems to me that collecting enough heat to warm a building on an 
>> average day would be simpler with some passive solar heaters built 
>> into the south wall, eg 
>> http://www.builditsolar.com/Projects/SpaceHeating/solar_barn_project.
>> htm
>>
>> Where I live near Philadelphia, PA, 1000 Btu/ft^2 of sun falls on a 
>> south wall on an average 30 F January day, so a 4 foot x 8 foot 
>> vertical south air heater with US R2 twinwall polycarbonate glazing 
>> with 80% solar transmission would gain 0.8x32ft^2x1000 = 25.6K 
>> Btu/day. With a 70 F building and a T (F) exit air heater temp and a 
>> (70+T)/2 average air temp inside the heater and a 6-hour solar 
>> collection day, the heater would lose about
>> 6h((70+T)/2-30)32ft^2/R2 = 48T+480 Btu/day. With a constant C cfm 
>> airflow, the collector would provide 6C(T-70) Btu/day of heat to the 
>> building... 2 1
>> ft^2 vents with one-way plastic film flappers and an H = 8 foot 
>> height difference would make C = 16.6x1ft^2sqrt(8'(T+70)/2-70)) =  
>> 33.2sqrt(T-70) cfm, and 25.6K = 48T + 480 + 200(T-70)^1.5 makes 543 = 
>> T + 4.15(T-70)^1.5, ie T = 70+((543-T)/4.15)^(2/3). Plugging in T = 
>> 100 on the right makes T =
>> 92.4 on the left, then 92.7, then 92.7, with C = 158 cfm and a
>> 6x158(92.7-70) = 21.5K Btu/day heat gain for the building, which 
>> might have just enough thermal mass and insulation and airtightness 
>> to cool from 70 to
>> 60 F by dawn... 60 = 30+(70-30)e^(-18h/RC) makes RC =
>> -18h/ln((60-30)/(70-30)) = 63 hours.
>>
>> And given the present low cost of PVs and inverters, we might heat 
>> the building with Mitsubishi or Fujitsu mini-split heat pumps on 
>> cloudy days (they work with an outdoor air temp down to minus 13 F), 
>> powered by PVs, using the electrical grid for storage instead of a 
>> 5000 gallon hot water tank. How many peak watts of PV would be 
>> required for space heating alone, with a COP of 3? A simulation using 
>> hourly EPW weather data could help estimate this.
>> http://apps1.eere.energy.gov/buildings/energyplus/cfm/weather_data3.c
>> fm/region=6_europe_wmo_region_6/country=SWE/cname=Sweden
>>
>> Then again, a solar village could have passive solar air heaters on 
>> each house and a large common underground heat storage tank with a 
>> geodesic transparent roof and a simple drainback hydronic collector 
>> on top of a floating insulated cover under the roof.
>>
>> Nick
>>
>>
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