When we think of hydropower, we think of thundering cascades of water spilling downhill through carefully crafted flumes and spinning enormous generators that make enough power to light up small cities. Hardly anyone thinks of a slow moving canal or river — except Emily Morris, CEO of Emrgy, a distributed energy startup located in Atlanta, Georgia.
The book Drawdown, edited by Paul Hawken, lists the top 100 things humanity can do to limit global warming. Number 48 on that list is in-stream hydro. Unlike other renewable energy sources, it is capable of producing electricity continuously 24 hours a day 365 days a year. Emrgy has developed a self-contained plug-n-play in-stream hydro module that can harvest energy from slow moving water streams. Each module produces about 10 kW of consistent hydro power and the system is scalable, meaning that generating more electricity is as simple as adding more modules.
The Emrgy system is designed for minimum disturbance of the local environment, including aquatic populations. Each module is constructed of inert materials that will not break down over time and add debris or foreign materials to the local water supply. Because each module is prefabricated, no construction needs to take place on site, which greatly reduces civil engineering costs and simplifies the permitting process.
The Emrgy modules are packed with innovative design solutions. The patented EnergyFlume® structure provides stability for each module and can speed up water flow by as much as 200%. The twin turbine blades complement each other and can capture as much as 70% of the energy available at any given location. The modules are self-starting and can accommodate water flowing in either direction.
Perhaps the most clever component is a nearly frictionless magnetic gearbox that supplies more of the rotational motion of the turbines to the generator than a mechanical gearbox could. The gearbox automatically compensates for overspeed and overtorque conditions.
Such small-scale hydro systems may seem like a minuscule part of the renewable energy picture, but Drawdown estimates that, if widely deployed, they could provide almost 4% of the world’s energy needs. That, in turn, would keep about 4 gigatons of carbon dioxide out of the earth’s atmosphere every year — equal to the emissions from 840 million fossil-fueled vehicles.
Emrgy has identified 15,000 miles of canals with low water flow in 7 US states that are potential candidates for its modular hydropower installations. Denver Water is one of the first organizations to install a prototype system. If that experiment goes well, more installations will surely follow. Water authorities and water districts consume lots of energy to pump and treat water. Recapturing some of that energy could significantly reduce their costs of operation and lead to lower bills for their customers.