We’re Sharing Cars and Spare Bedrooms in Cities. How About Energy?

The sharing economy is built on the principle that one person’s trash is another person’s treasure. By making excess capacity available to others – a spare bedroom to an out-of-town visitor, an idle vehicle to a partner in a carsharing program – the sharing economy opens up new “win-win” opportunities throughout the economy and serves sustainability goals by making better use of our existing resources.

It is no surprise that the sharing economy has taken off first in cities, where there are many more opportunities to match excess resources with unmet needs, and where the physical barriers to sharing are low.

Could sharing in cities also help address our nation’s energy challenges?  A few startups are using crowdfunding principles to fuel renewable energy investments. But some of the most promising sharing opportunities actually use ancient technologies to repurpose energy that once was wasted.

Here in Boston, the French company Veolia just built a $112 million, mile-long pipe to feed unused steam from its power plant in Cambridge into Boston’s existing district energy system. That system supplies steam for heat, cooling and other purposes through a network of underground pipes to 70 percent of the city’s high rises, as well as major institutions and biotech companies. By reusing once-wasted heat, the system will reduce carbon dioxide emissions by as much as taking 80,000 cars off the road.

There is a good chance you have never heard of district energy, and with the exception of the occasional wisp of steam from a manhole cover on a rainy day, district energy systems are invisible to most of us. But they are surprisingly widespread, with more than 700 such systems in the U.S.

District energy has a great deal of potential to cut fossil fuel use. Combined heat and power projects, like the one in Boston, can boost the overall efficiency of a gas-fired power plant to as much as 80 percent. Seattle is looking at using waste heat from data centers for district energy. St. Paul, Minnesota, recently installed solar thermal collectors on the roof of its convention center, with excess hot water from the system fed into the city’s district energy network. Klamath Falls, Oregon, has long had a district energy system powered by geothermal energy. Thermal energy can even be stored, enabling energy collected at one time of day to be used to heat or cool buildings later on.  

District energy doesn’t fit easily into our mental image of the sharing economy. The technology is more steampunk than iPhone and the organizational model in many cities is more old-school regulated utility than ad hoc social network. But together with recent research out of the London School of Economics and Political Science (PDF) documenting the inherent energy efficiency of dense urban building forms, district energy shows how cities are uniquely positioned to address our energy and environmental challenges.

The ability to share resources – whether spare bedrooms or excess heat – is a big part of the reason why.