In an exciting move to make our store even greener, the Co-op recently moved ahead with a plan to install a new solar-powered hot water system. This will help meet the hot water needs of the building using clean, renewable solar energy. The system is expected to reduce the need for natural gas by about 620 therms each year. And, by eliminating the combustion of this fossil fuel, it will prevent 4.5 metric tons of CO2 from entering the atmosphere, thereby taking another small step to address the problem of climate change.
Our mission statement asserts that the Co-op is “an economically and environmentally sustainable, cooperatively owned grocery business...” and once again we have an opportunity to prove it. As many of you know, your Co-op has been harvesting solar energy since March 2005 using our rooftop solar electric array. This photovoltaic system produces electricity directly from the sun and has been a great success. (You can check out the amount of electricity being produced by looking at the meter in the store entry.) Now, thanks to the growing patronage and the financial success of the Co-op, we can take further advantage of our rooftop solar resource.
The installation of the solar hot water equipment is expected to begin in February, and we hope to have it up and running this spring. The current design calls for installing clearly labeled piping in the ceiling area of the store retail space. This will provide an opportunity for shoppers to be reminded of how we are using the sun to reduce our carbon footprint. In addition, we expect to provide real-time energy production data on the Co-op website. Stay tuned for more information on this.
How it works
The new solar thermal system will incorporate 10 collector modules (approximately 270 square feet of collector area) that will be mounted on the roof. A liquid will be heated as it circulates through these modules. This hot liquid will pass through a heat exchanger giving up its heat to water stored in a preheat tank. This preheated water will feed the regular hot water heater thereby reducing the amount of heat (and natural gas) required.
How we’re paying for it
One really exciting aspect of this project is the innovative way that we will be paying for the system by using a Thermal Power Purchase Agreement (PPA). Under this contract the equipment will be installed by Resource Solar, LLC (http://resource-solar.com/) and they will own and maintain the system for the first six years. The amount of energy supplied by the system will be metered and the Co-op will pay for that energy at a fixed rate of $0.79 per therm (which is similar to our current rate for natural gas). At the end of six years the Co-op will buy the system for less than a third of the original installed cost. The advantages of this approach are that the Co-op will buy the system for about half of the after-rebate system cost with approximately 80% of the system life left. In addition, for the next six years we will pay a lower rate for the energy produced by the system than what we likely would have paid for natural gas.
Other steps toward sustainability
In addition to our existing solar electric system and this planned solar thermal system, we have worked hard to make your store more energy efficient. When we renovated our current space back in 1998 we paid a lot of attention to energy efficiency; we installed energy efficient lighting and occupancy sensors, high efficiency refrigeration systems, a bit of day-lighting where we could make it work, heat reclaim systems, energy-star certified equipment, and low-flow water fixtures (for more information go to http://www.willystreet.coop/sustainable_store). We also buy windpower generated electricity from MG&E. And of course, we strive to buy as much local food as we can, greatly reducing the energy used for transportation and intermediary storage. So, while there are always more steps to be taken, you can take pride in the fact that your Co-op is constantly striving to enhance the sustainability of our store.