[Greenbuilding] Swedish solar-heated village

[John Daglish]

Dan

Look at the video to see were the Danes are going :)

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

Regards

John
John Daglish
Paris, France


2015-11-30 19:31 GMT+01:00 Dan Johnson <danjoh99 at gmail.com>:
> Thanks John for the Danish examples of district heating powered by
> centralized solar-thermal. A few questions come to mind:
>
> 1. What is the installed and operating cost per BTU for this system, versus
> the same solar-thermal panels on individual houses without the district
> loop? Or compared to a Nick-Pine-style low-mass sunspace on each house---or
> to Soldier's Grove, Wisconsin? It seems like this Danish system adds the
> cost of the district loop, yet has all the same problems as distributed
> solar heat.
>
> 2. Problems being primarily: there is no heat when the sun's not shining.
> For this, Nick suggested a heat pump and PV panels, "using the grid for
> storage". I pointed out that the grid has no storage, and the PVs are more
> like a shady carbon offset scheme, so perhaps there is only "storage" in the
> wishful abstract.
>
> 3. The Danish system solves the problem of
> no-heat-when-the-sun's-not-shining using 4000m3 hot-water storage [8.8
> million pounds of water], and by burning natural gas in a central boiler and
> sending hot water through the district loop. This is not much different than
> homeowners storing hot water and burning their own natural gas at each
> house, is it? From the brochure linked here:
> http://www.sonderborg-fjernvarme.dk/wp-content/uploads/2013/06/Solparken_folder_gb.pdf,
> "The boiler plant is able to supplement the solar heating with up to 5
> kilowatt [only 17 kBTU/hr? Something lost in translation]. The plant
> consists of two boilers that run on ***CO2-neutral biofuel***" Magical
> stuff. where do I buy some? Why don't we just replace ALL natural gas with
> this? :-)
>
> 4. Compare the Danish scheme to PG&E in California, which burns NG at a
> generator to make electricity (combined cycle claims 41-61% efficiency,
> https://en.wikipedia.org/wiki/Combined_cycle; say 51% average), sends the
> electricity to homeowners, who then run heat pumps (COP=2.5?). Crude math
> says N BTU delivered / 2.5 / 0.51 = 0.78N BTU at the power plant, neglecting
> line losses. Burning the gas at home would be N BTU @ 93% efficiency = 1.07N
> BTU input, neglecting delivery costs. So using the heat pump is a more
> efficient use of gas? Perhaps a district-scale, combined-cycle NG
> co-generator that energized a central heat pump and fed a district loop
> would be the best? Could one of these be built at each existing powerplant,
> using the existing cooling water for a water-source heat pump? The
> powerplants are not in-town, where the heat is needed. :-) Dan J
>
> Dan Johnson
> 510-325-5672 cell
>
> On Thu, Nov 26, 2015 at 7:33 AM, John Daglish <johndaglish at gmail.com> wrote:
>>
>> No seems OK efficiency also varies with temperature, though it seems
>> odd the sun is shinning no where else http://en.sat24.com/en
>>
>> see page 2 a standard flat plate collector  ... collected heat 45%
>> http://www.lth.se/fileadmin/ht/Kurser/MVK160/Project_08/Fabio.pdf
>>
>> The Sunmark collector includes anti-reflective glass and some models a
>> transparent anti-convection current screen between the glass and
>> absorber reducing heat loss through the glazing.
>>
>> There is a 4000m3 of hot water storage at Sønderborg
>>
>> http://www.sonderborg-fjernvarme.dk/wp-content/uploads/2013/06/Solparken_folder_gb.pdf
>>
>> Expected share of solar heat in total annual plant production is 20%
>>
>> John Daglish
>> Paris, France
>>
>>
>> 2015-11-26 14:43 GMT+01:00 Don Lush <donlush at uniserve.com>:
>> > 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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