MIT's Carbon Black Innovation: Infrastructure That Stores Power

As researchers and energy companies around the globe invest heavily in the exploration of new clean energy sources and related technologies, several new discoveries are emerging, but whether they will ever reach the market is still unknown. Out of thousands of potential new discoveries, few are likely to ever be used in practice, but some could potentially come to market thanks to the international drive for a green transition. One innovative discovery being presented by researchers from MIT is an energy-storing building material made by mixing cement, water, and carbon black.

Scientists at the university believe they have discovered a new material that could be scaled for use in roads and building to provide renewable energy. The researchers mix the cement, water, and carbon black to produce a supercapacitor. They have previously tried creating battery-like properties in building materials by mixing concrete with graphene-based carbon nanotubes. However, as nanotubes are expensive to manufacture, this was not viewed as viable for use as a commercial building material. In contrast, carbon black is produced from the incomplete combustion of coal, vegetable matter, or fuel, and is much cheaper to make. 

The group at MIT found that mixing cement, water, and carbon black created a "fractal-like," electron-conducting network. The final product is used to form small plates, that are 1mm thick and 10mm wide and coated in a potassium chloride membrane. There are two electrodes made from the material, separated by an insulating layer, which lets them become a powerful supercapacitor. When provided with power, the plates can light a series of LEDs, which, the team believes, could make them useful in roads and buildings, when used to store energy. 

But there are still challenges facing the team, as ensuring that the plates are able to keep both their energy-storing capability and structural strength is complicated. While black carbon has greater energy-storing properties, using more of it can weaken the concrete. The researchers believe using 10 percent black carbon in the mix provides the best balance. However, more can be used in scenarios where structural strength isn't so critical. 

This is not the first time researchers have attempted to use innovative building materials for the purpose of storing energy. It is widely believed that thermal storage can be used in buildings to provide energy. When the temperature inside a building increases, innovative construction materials heat up, storing heat (thermal energy) for later use. While this technology has been largely overlooked in the past, greater political support and investment in a green transition could be just what was needed to encourage more research into the development of innovative building materials. For example, scientists at Lawrence Berkeley National Laboratory are exploring ways to overcome the challenges faced in water-based thermal energy storage. The team are developing new building materials and systems to be used for heating and cooling, with advances in the technology already being reported. 

Ravi Prasher, Berkeley Lab's Associate Lab Director for Energy Technologies, explained "It is very challenging to decarbonise buildings, particularly for heating." He added, "But if you store energy in the form of the end use, which is heat, rather than in the form of the energy supply, which is electricity, the cost savings could be very compelling. And now with the framework we've developed, we'll be able to weigh the costs of thermal energy storage versus electrical storage, such as with lithium batteries, which has been impossible until now."

Developing these building materials could be key to decarbonisation and achieving a green transition, with buildings in the U.S. accounting for 40 percent of the country's energy consumption. Around half of this energy is used for heating and cooling equipment, as well as water heating and refrigeration. And this proportion of energy usage is expected to increase as the population increases. In addition, the eventual fall in natural gas use will increase reliance on the ageing electric grid. Therefore, the use of thermal energy storage could help alleviate some of the pressure on the U.S. grid, as well as decrease the proportion of traditional renewable energy needed to be used in buildings. 

However, significantly more research and investment are needed in thermal storage for it to be developed for commercial use. At present, most materials being analysed face significant challenges when it comes to commercial rollout. While the innovations being seen at some of the top U.S. universities are promising, it is unlikely that we will see any wide-scale use of these types of materials for decades to come. However, their use in the long term could help to meet the growing demand for renewable energy and decrease reliance on other sources of clean electricity.

By Felicity Bradstock for Oilprice.com

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