Have you ever wondered why the Sunshine State isn’t leading the world in the production of solar energy? There are a combination of factors involved – some political and economic – but two engineers at the University of Florida have shed light on how the electrical challenges that come with using widespread solar energy could be overcome.
Most people think blackouts are caused when there’s not enough energy feeding into the grid. That’s true, they are. But too much energy can cause blackouts, as well. Power plants, be they coal, natural gas or nuclear, can produce a calculated and predictable amount of energy, while solar and wind power have natural fluctuations. These highs and lows of energy have to be managed so the grid won’t crash from too much or too little energy. Maintaining the grid is challenging. Shutting down and ramping up large power plants isn’t energy efficient, and storing excess energy in huge batteries isn’t cost effective. So the balancing authorities that maintain the grid have placed limits on larger sources of variable energy, like solar, to protect the grid from crashing from what are considered to be unmanageable highs and lows.
But are they unmanageable? That’s what UF engineering professors Sean Meyn and Prabir Barooah asked. They began looking at load balancing, at supply and demand. Knowing they could never control an unpredictable solar supply, (never control the weather), they focused on how they could meet a larger solar supply with a more flexible demand. They wanted to make use of the highs and lows.
Knowing that 75% of our country’s energy consumption goes towards keeping buildings habitable, they set their target: comfortable indoor spaces.
Unlike most residential units, large commercial heating, ventilation, and air-conditioning (HVAC) systems are operated via computer command. And just like most pools and their pumps in the state of Florida can be shut down by utility companies in the event of a hurricane or other emergency, most commercial HVAC systems in the state – they theorized – could be asked, via software, to absorb shocks of excess solar energy into higher variable speeds of their constantly spinning fans.
But would this disrupt a building’s temperature? They tested the idea. On the UF campus, with the blessing of the facilities division, they sent a signal to Pugh Hall’s HVAC system from a remote location. After operating from the simulated highs and lows of energy from an average day’s solar activity in Florida, there was no noticeable change in the building’s temperature.
The team chose Pugh Hall because it is Leadership in Energy & Environmental Design (LEED) certified, a criteria that was important to the National Science Foundation, who funded the research. To Meyn, who is a professor of electrical and computer engineering, the director of the Florida Institute for Sustainable Energy, and a recent expert witness for a congressional committee on energy, efficiency is actually not very important.
“If everything is run by solar, who cares about efficiency!” says Meyn. “By using this software we might be 1-2% less efficient in our approach to cooling a building. But we could be producing 10 to 50% of our energy from solar power around the state.”
There’s nothing complicated about the technology itself; switching a building over to run on this system only takes a few hours, and a small minority of the state’s commercial buildings could tip us towards a majority solar state. The biggest hurdle, both professors agree, will be getting building owners on board with the idea.
Besides commercial HVAC systems, there are other energy demands that can be flexible. For instance, most people aren’t concerned about the exact time of day that their pool pump is running. Certain manufacturing industries – like aluminum – can roll with the punches of variable surges of energy. Desalination plants won’t go under if they follow the energy tides of solar power. These models – they’re called ancillary services from flexible loads – are some of the brightest solutions on the horizon.
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