The Saturday night before last was a cold one in Eastie – the low temperature reached a frosty 17o F. It was a reminder that, despite the spring-like warmth we’ve been experiencing these past two weeks, winter is still hanging on.
And yet – right in the heart of Eastie – lemons, limes, and avocados made it through the night no worse for wear, thanks to Eastie Farm’s greenhouse. The coldest temperature they experienced was just a shade under 60o F. That’s a full 40 degree temperature difference!
The secret ingredient here is the heat below our feet: our greenhouse uses a ground-source heat pump to keep plants and people cozy all winter long. Water is pumped through pipes in three 455-ft deep vertical wells, picking up heat as it goes. When the water returns to the surface, that heat is concentrated and dumped into the greenhouse air, all without any of the fossil fuel inputs and carbon emissions associated with traditional greenhouse heating systems. Our system runs on the City of Boston’s Community Choice Electricity Green 100 plan, which supplies 100% renewable electricity.
Thanks to top of the line efficiency, geothermal systems like ours are actually cheaper than fossil fuel-based systems in the long run. For every unit of electricity consumed, our system is capable of moving five units of heat. That’s 500% efficiency as compared to the ~95% fuel use efficiency of modern natural gas furnaces. Over the years, the lower input costs defray the upfront expenses.
The prospect of year-round, space-efficient growing makes greenhouses, freight farms, and other controlled environments attractive options for localized urban food production. However, climate control and lighting consume a lot of energy, so it’s crucial for the environmentally-conscious grower to explore the low- and zero-emissions technologies available to them.
We are grateful to have received amazing support from GrowBoston, the Massachusetts Department of Agricultural Resources, and the Massachusetts Clean Energy Center in the development and activation of our greenhouse, and hope that fellow Earth-stewards will join us in availing themselves of the grants, rebates, and technical assistance provided by these and other agencies as we forge a cleaner, greener future together. We are also eternally thankful for the dedicated volunteers and community members who bring our mission to life every day.
