Energy Systems at Sieben Linden

With my new found passion for energy commons, I was most curious about how Sieben Linden (eco-village in Germany - see previous post)  balanced their energy needs.

This picture says it all:  Current solar income with biomass.  This picture shows the storage area for Sieben Linden's wood heating supply.  Cool to put solar PV (current solar income) on top of it.

Biomass in Europe usually implies wood (biofuels is everything else). Europeans are VERY sensitive to biofuels due to their tremendous influence on global food prices and how biofuels are sacrificing rain forests in 3rd world countries (palm oil, soybeans, etc.).

Here's a summary of their energy systems from the web site:
The average resident uses about 500kwh per year (compared to the average USA residential usage of 11,000Kwh per year.) which 1/3 of what the average German uses. There is no electrical energy used for heating water or space.  There are multiple solar PV and thermal arrays around the community.  A total of 47KW PV with about 4m ² (40 ft ²) of solar PV panels per resident which supplies 85% of their annual needs.  Sieben Linden's solar PV arrays are grid-connected [Germany is on a feed-through tariff system (USA uses net-metering)].  Since there are strict rules of no toxic materials allowed on site, there is no battery storage.
Heating is done mainly through biomass = wood.  There are very large, multiple storage areas for cut wood logs ready to be consumed by fireplaces.  Each fireplace's exhaust extends over 20ft above the roof.   It appears this is more to get the emissions higher up and airborne,  than for fire prevention.

Hot water appears to be 100% from solar thermal panels.  There are a LOT of solar HW panels.  They have a biomass gasification generator (turns wood to heat + ?steam?) which appeared to me to be a simple boiler.  The unit is hooked up to three of the large buildings in a central district type configuration.  This is also VERY commonplace in Europe.  It's easy to interconnect multiple dwellings to one central heating system and far cheaper than having individual heating units in each building.

Propane appears to be used only in the common kitchen areas. I don't know if it  was piped to other homes.
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My view on this:
An eco-community's priority should be for a long-range smart energy plan that focuses on self sufficiency and micro-grid power.  By tying into a main grid (no matter where you are - even in California) there is a direct connection and support of coal, nuclear, etc. utility mega-corporations; even though one is investing in green power RECs.

I don't quite understand Sieben Linden's reluctance for battery or other electrical on-site storage.  There are benefits of using new battery technologies that would avoid lead acids and toxic-plated batteries on-site.  There are also alternative storage mechanisms such as compressed air, hydrogen, pumped water storage,fuel cells, or even cutting edge technology such as the 'cube'.

I was really surprised to see all the wood. I always thought that burning wood was eco-uncool. But after Austria and Sieben Linden, I have changed my mind.  I will start harvesting and burning more wood at 7L.  I hope to eventually find a small gasificaiton  generator to make electricity (co-gen + tri-gen) from wood.   I'll probably have to import if from Europe or Asia.

One of the guiding principles in permaculture and cradle-to-cradle is to celebrate diversity. That has always been they key to any system = especially energy.  Sieben Linden does a good job at this. It has wood, grid electric, solar PV, solar thermal, and propane.  I thought for sure I would see a wind generator - which has a nice parity balance to solar systems. But, alas - none to be found.  Seems that the wind speeds are just not high enough.  Bullocks, I say.  For mere hundreds of euros a small wind generator can be erected, not very high up and supplement the solar PV panels.

The biggie at Sieben Linden is solar thermal.  I am always surprised in the USA and especially in California, that we don't have more solar thermal.  It is so much more efficient, so much easier and much lower cost to construct.  But with freezing temperatures, and shady contractors, the USA has a history of bad experiences. Once  freeze-proof silicone neoprene piping comes out of NSA's labs though that will change.

I wasn't able to find out if their solar thermal panels use food-grade glycol - which is a toxin.