American history buffs and foodies know the story of the three sisters of agriculture, a brilliant combinatorial planting technique practiced by Native Americans.  This uniquely American agricultural invention elegantly illustrates the concept of synergy.  Synergy is defined as the interactions of two or more things combined to produce something greater than their separate efforts could produce.  The three sisters are maize (aka corn), beans, and squash.  Corn grows tall, but has shallow roots and a need for nitrogen to support growth.  Bean plants need climbing material to produce more beans and fix nitrogen captured from the air into the soil.  Corn provides the stalk for climbing, and beans provide the nitrogen for corn to grow tall, and there’s one synergy.  Squash is a low-growing plant that keeps out weeds, shades plant roots to retain moisture, and benefits from the shade provided by corn stalks.  There’s another synergy.  Combine the three together and you increase yields more than possible from a single crop planting.

Similarly, renewables-based generation, energy storage, and grid analytics/software are the three sisters of the Smart Grid – leveraging the synergies of their technologies to achieve greater reliable electricity yield than each technology could independently produce.   These three technologies can deliver their combined benefits for utility-scale generation as well as distributed generation and microgrids.  

Renewables, the first sister, are categorized as intermittent or steady-state sources of electrical energy.  Wind and solar are intermittent.  Geothermal and hydro (in most cases) are steady-state.  While steady-state is easier to manage, it’s not as well-distributed or readily accessible for most countries.  Solar and wind have distinct advantages in the fact that the sun shines everywhere and the wind is usually not too picky about where it blows.  Solar has great flexibility in where it can be placed –rooftops everywhere can be potential sites for distributed generation.  But intermittency is a vexing problem for planners and grid managers because it is vital to grid health to minimize fluctuations of energy.  Clouds passing over solar panels or temporary drops in wind create those fluctuations.  This is where the second sister comes into play. 

Innovations in battery technologies are transforming energy storage into cost-competitive solutions that partner well with intermittent renewables like wind and solar to deliver steady state power.   There are new technologies that overcome concerns of energy density, flammability, toxicity, and achieve grid-parity pricing.  Energy storage is the second sister of the Smart Grid.  Stationary and mobile (EV) forms of energy storage can play significant roles in utility scale and distributed generation utilizing solar and wind, because it can be deployed to smooth out temporal or weather-based fluctuations.  Renewables and energy storage deliver a potent synergy, but a third sister is needed to help manage these assets as they are integrated into transmission or distribution grids.

Grid analytics and grid management software are needed to manage increasing numbers of renewable generation and energy storage assets.  Utilities are building out IP-enabled networks to accommodate bi-directional communications, and this activity opens up opportunities for remote realtime monitoring and management of these new assets anywhere in the grid.   Realtime management of dispersed assets needs software to organize grid management activities.   It also requires analytics to provide proactive intelligence about conditions and predictive performance of grid networks and devices.  Grid analytics and management software enhance the reliability of electricity on the grid – a valuable synergy with renewables and energy storage. 

These technologies will accelerate the delivery of the benefits of the Smart Grid, but today exist as separate solutions.  Could a three sisters solution for the Smart Grid be the next brilliantly synergistic American innovation?  Like the Native Americans of the past, system integrators who specialize in distributed generation and microgrids can play a key role in creatively combining these technologies into solutions that fully leverage their synergies.  These solutions could also be exported globally to address developed and developing world energy needs.