Smartphones, smartcars, smartTVs - everyday we seem to hear the word "smart" in front of a new word. You may have also heard about the smart grid. This one happens to be very important for the future of solar energy. In fact, without a smart grid, it is very difficult to imagine a world where solar energy can generate the lion's share of electricity in a modern economy. So what exactly is the smart grid? U.S. Department of Energy defines it as: "Like the Internet, the Smart Grid will consist of controls, computers, automation, and new technologies and equipment working together, but in this case, these technologies will work with the electrical grid to respond digitally to our quickly changing electric demand.".
As we discussed in an earlier post, one of the main disadvantages of solar energy is its intermittent nature. When we compare the output of a single solar panel to that of a nuclear power plant, the difference is very clear. The output of the nuclear power plant is more or less like a straight line: steady, consistent and predictable. The output from the solar panel, however, is a very different story. Not only is there zero output at night when it's dark, but also the generation during the day is erratic, inconsistent and uncertain. The day and night cycle creates an obvious limitation to solar energy potential: the solar panels sit idle during the night. Changing cloud cover during the day can also drastically change the amount of solar electricity your panels can generate.
Smart Step One: Forecasting
Compared to the steady output of conventional power plants, such as coal and nuclear, the variation in renewable energy output creates a lot of headache for the grid operators who are not equipped to deal with distributed power sources which ramp up and down based on weather conditions. But what if we could predict the variation in solar energy output? Forecasting solar energy generation based on changing weather conditions has a lot of potential to increase the "reliability" of solar energy by reducing the uncertainty of solar power. Armed with this information, grid operators can balance the electricity load by combining different generation types in a dynamic fashion. Thus, one of the cornerstones of smart grids for solar energy is forecasting, but this is not all.
Smart Step Two: Optimizing the Grid for Distributed Generation
The current generation of electric grids is a product of history. For more than a century, grids have been designed to move the power from a few concentrated sources through a vast network of transmission lines and push the electrons to where they are needed. They were optimized for one-way traffic, and therefore the current architecture resembles the trunk and branches of a tree. In contrast, in the distributed generation model, power is generated by many different sources, big and small. From a 5 kW rooftop solar photovoltaic system to a 10 MW wind farm, many nodes connect to the grid and create two-way traffic. Thus, what we need is a grid which resembles the Internet: a dense network with large clusters but also many interconnections between the different nodes. As we discussed above, the output from a single solar panel can change drastically over time, but what about a million solar panels, thousands of wind turbines and hundreds of hydro dams distributed across a wide region? It turns out there is natural balance when we build a portfolio of renewable energy sources, as their peaks and troughs cancel each other out to a large extent. If only we could have an efficient grid that can interconnect these renewable sources.
Smart Step Three: Dynamically Storing Electricity
A smart grid is not only a new way to establish two-way traffic between the sources and final uses of electricity. It is also a way to bring electric vehicles into the fold as a way to store energy. Since most vehicles are parked 95% of the time, their batteries can be used as an extension of the electricity grid. Imagine being able to divert the surplus wind and solar energy to various forms of storage, including the batteries of electric vehicles. Such a system could then tap into this stored power when the demand for electricity peaks.
Smart Step Four: Demand Side Management
Although this may sound a bit invasive to some homeowners, giving the grid operators the ability to control some of the power-hungry appliances at homes can alleviate the pressure on the grids. For example, Toronto Hydro (a utility in Canada) has the ability to cycle down individual air conditioner units and water heaters if the customer has a small device installed at their home. This device not only allows the utility to adjust the demand, but it also gives the homeowner the ability to monitor their electricity usage in real time.
As you can see, the intelligence of the new generation grids will not be based on a single factor, but a multitude of capabilities working together to create a more nimble, efficient, reliable and clean electricity system. Solar energy can play an important role in tomorrow's smart grids by providing a significant amount of power when it is needed the most: late mornings and early afternoons.