Insights from Germany (Part I)
In July, as part of a delegation traveling to Germany to meet with experts and policymakers about renewable energy, I visited a recently transformed WWII air raid bunker in Hamburg, Germany. The imposing 140-foot high concrete bunker with its 10-foot thick walls and 13-foot thick ceilings was built in 1943 by the German war machine to serve as a platform to fire at Allied air forces, while protecting tens of thousands of Hamburg citizens inside its seemingly impenetrable walls. After sitting empty for over 60 years, this mammoth structural reminder of the past is now a glimpse of the future. Serving as an “energy bunker,” it now supports solar panels and houses energy equipment that produces renewable energy for the surrounding community transforming it into a a community asset.
The Hamburg energy bunker’s integrated system combines a large roof-mounted solar thermal array; a side-mounted solar PV array; a biogas-fired combined heat and power unit; a wood chip-fired boiler; waste heat recovered from a local industrial process; and, a nearly 600,000-gallon hot water storage tank built inside of the bunker. This innovative community energy system uses local sources of renewable energy to meet the energy needs of a neighborhood covering approximately 300 acres by generating enough energy to heat approximately 3000 households via a hot water district heating system and generating enough electricity for approximately 1000 homes.
In the future, the municipally owned energy system plans to purchase excess wind power from the grid when it is at a lower cost and store it their hot water tank – their thermal battery. We heard repeatedly that the need for such “power to heat” storage is growing rapidly as more wind and solar is added to Germany’s and Europe’s electric grid. The practice of storing excess wind and solar energy as thermal energy is also beginning to occur here in the U.S.
When the integration of thermal storage is complete in the Energy Bunker, customers of this integrated system will efficiently heat and electrify their homes with energy from wind, solar, biogas, biomass (wood chips), and waste heat recovered from local industry, resulting in a 95 percent reduction in their carbon emissions. This WWII relic has been transformed from a reminder of a dark time into a community asset that not only demonstrates a better future of energy it also offers the best views of Hamburg from its 100-foot high, 360-degree observation deck.
The energy bunker in Hamburg is just one example of how energy generation, storage, and delivery is evolving in communities around the globe. Nearly every day I learn of another example of how energy is changing at the community level as more communities take leadership to understand and plan to secure their energy future.