The Sun’s Heat: Now On Demand

Nanotechnology makes the seemingly impossible true: Trapping the sun’s heat for release later, whenever and wherever you need it.

sun energy


MIT’s researchers have discovered a way to blend carbon nanotubes, current media darlings of the chemistry world, with an existing material used for storing heat energy. In doing so they’ve come up with something incredible: A new chemical, far cheaper than its competition, that can store solar heat energy with about the same density as the electrical power we jam into lithium-ion batteries. What could this mean? If we’re lucky, in the sunnier parts of the world it could mean an end to home heating bills… but that’s just the start.

The material works like this: The molecules are simply exposed to the radiation of plain, bright sunlight. Incoming energy excites the molecules, and causes some of their cleverly engineered chemical bonds to “flip” as they get excited. This means a tiny sliver of energy is stored in each bond, and if you have trillions of the molecules in a bulk material, this energy can quickly add up. To discharge this solar-thermo-chemical battery, you need a trigger such as a small burst of heat or a catalyst material, and the bonds begin to flip back to their resting state, releasing the stored energy as heat.

It’s much cheaper than an earlier success, which contained the rare and expensive material ruthenium, and it’s also about 10,000 times better than its competitors at storing energy densely–in fact it can fit in about as many units of energy per cubic centimeter as devices like lithium-ion batteries, a tech we now take for granted.

The benefits of this new material are myriad: It’s cheap and doesn’t degrade, so it can be recycled in the same apparatus day after day after day. Unlike other systems that grab solar energy and convert them into electrical energy, it can both store and release heat–with potential efficiencies in energy or design. It’s an experimental material, but the MIT team is already looking at improving it and adapting the new tech.

But the implications of this sort of material are easy to overlook, because they seem so obvious. What if you could store the sun’s heat energy falling onto your home’s roof all day and then release it to heat your rooms up only when you get home after the late-night movie–long after darkness has fallen? No need to burn any gas or electricity to heat your home before bed. There’s also no reason you couldn’t supplement the solar-electric roof panels of your future electric car with a solar-thermal cell, and use it to capture heat in the office parking lot all day and then warm you on the way home, which would result in much higher efficiency for whatever fuel system your car uses.

With some design engineering spit-and-polish, it’s even plausible the tech could result in heat “batteries” that you’d think about the same way you currently do for a bunch of AA cells. The sun’s energy is boundless. The only thing keeping us from using it is our ability to convert it to electricity and store it. This is a giant leap toward solving that problem.


[Image: Flickr user guldfisken]

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