Scientists have designed “melted chocolate chip” bricks to efficiently store energy generated by renewable energy sources.

Engineers from newcastle University have come up with a surprisingly new energy storage system that surrounds bricks with heat like melted chocolate chips in muffins. They are efficient, scalable, safe, inexpensive and can be used in existing coal-fired power plants, the team said.

Renewable energy is a key component of any plan to reduce the impact on the planet, but storage remains a major obstacle to making these systems viable. Recent solutions include Tesla’s giant lithium-ion batteries, or unconventional energy storage, such as molten salt or silicon, heavy rail cars on steep ramps, and huge blocks suspended in mines or stacked on towers.

Now, there’s a new entry on the list — the MGA brick. These bricks are only 30 x 20 x 16 cm (11.8 x 7.9 x 6.3 inches) in size and are made of materials with high thermal conductivity, so they can be easily heated to store energy and cooled when needed to release energy again.

To do this effectively, these bricks consist of two main parts. There is a solid substation that is fixed together in the shape of a brick, and the entire substring is embedded with meltable particles. The team described the design as similar to chocolate chips in muffins.

“Imagine that the substation is part of the cake, which keeps everything in shape when heated and distributes the heat quickly,” said Mark Copus, an engineer with the project. “Other particles, represented by chocolate chips, melt and store heat through the solid-to-liquid phase of change.”

The idea is that these MGA blocks can be heated with excess energy from renewable sources during peak output periods and stored for use during peak demand. Alternatively, they can be stacked in other power plants to help recycle waste heat into the system.

The heat they release can be used to overheat water into steam to run turbines without burning coal. This means that MGA blocks can be retrofitted into decommissioned or soon-to-be-decommissioned coal-fired power plants to smooth the transition to renewable energy. As a reward, this also eliminates the need to build new or decommissioned facilities and eliminates the need to upgrade the grid infrastructure.

“Emissions from coal-fired power plants are the single largest source of greenhouse gases that contribute to global warming,” said Professor Erich Kisi, co-founder of MGA Thermal. “Transforming coal-fired power plants is a win-win way to provide clean base-load power and help prevent job losses from power plant closures.”

The team says the MGA block has a number of other advantages. The system can be easily expanded by adding extra blocks, potentially storing up to several gigawatt hours of energy, and they are made of cheap and rich materials, so their cost is obviously 10% of the price of lithium batteries of the same size, and they can still reportedly export the same amount of energy. These materials are also non-toxic and do not pose a risk of explosion or leakage of harmful chemicals.

MGA Thermal is building a manufacturing facility in New South Wales to expand the production of the block to commercial levels and, in partnership with E2S Power AG of Switzerland, has begun designing systems to reuse coal-fired power plants in Europe to use the new block.