| Energy storage
TWEST™ – repurposing coal fired plants as thermal energy storage facilities
The phase out of hundreds of GW of coal plants globally is creating an immediate challenge: what should be done with these valuable assets? E2S Power’s innovative idea is to replace the boilers with thermal energy storage using its TWEST™ (Travelling Wave Energy Storage Technology) concept. This repurposes potentially stranded assets while addressing the urgent need for increased energy storage capacity worldwide
Fabrizio De Candia COO, E2S Power
As we strive for a carbon-free world, the share of global power generation from intermittent renewable sources is increasing rapidly. This growth will drive the need to address intermittency, dependable capacity, and grid stability with energy storage solutions. It has been estimated that the large-scale storage market will increase by ten times in the coming years. At the same time, at COP 26, more than 40 countries agreed to phase out their use of coal-fired power and several nations have already committed to phase out coal power plants by 2030 and earlier. This means that hundreds of GW of coal-fired power plants will be decommissioned, raising the following questions: how do we ensure dependable capacity? how are we going to repurpose these power plants? how do we transition economies where these plants are located to a carbon free future? E2S Power is aiming to address these challenges with its thermal energy storage solution. The technology is based on the concept of reusing most of the fossil fuelled power plant’s equipment and infrastructure and turning it into a clean energy storage plant.
For this purpose, E2S Power has developed a simple and compact system that converts
surplus electrical energy from wind farms or solar power plants into heat, stores the heat using innovative high energy density materials, and, when required, generates superheated steam at constant temperature to produce electricity using the existing coal plant steam turbines. A novel energy storage system, TWEST™ (Travelling Wave Energy Storage Technology) – simple, compact and self-contained – is at the heart of the E2S power plant conversion concept. TWEST (Figure 1) consists of three key components: 1 – electric radiant heaters; 2 – MGA storage blocks; and 3 – steam generators in an insulated enclosure.
The electric heaters are designed for temperatures higher than 1000°C and facilitate heat transfer to the MGA storage blocks during charging.
The MGA (Miscibility Gap Alloy) blocks (Figure 2) are a high energy density storage medium developed by partner company MGA Thermal. They are made of graphite and aluminium arranged in blocks similar to building blocks or bricks. One component (aluminium) has a lower melting point (660°C) than the other (graphite) with the phase change latent heat providing high performance energy storage. Graphite, with a
2 1
3
Above: Figure 1. TWEST™ (Travelling Wave Energy Storage Technology). 1 – electric radiant heater; 2 – MGA storage blocks; and 3 – steam generator
higher melting point, remains solid and acts as a matrix, keeping the block in a solid form and embedding the melting particles. Thanks to the phase change, better energy storage density is achieved compared with other thermal energy storage technologies.
The steam generators, employing advanced high-temperature-resistant alloys, are mounted in the MGA storage blocks. E2S Power’s proprietary “Travelling Wave” technology ensures that a constant steam temperature is delivered to the host plant.
The system is packaged in a standard “container” module that allows stacking up as required to provide the storage capacity wanted and the plant footprint needed to adapt to a variety of power plant sizes and configurations (Figure 3).
The superior energy density means that the installation is compact.
TWEST is designed to easily integrate into an existing power plant (Figure 4), with three main interfaces: electricity supply for charging the system; feedwater input; and steam supply into the existing steam cycle.
How it works Above: Figure 2. MGA (Miscibility Gap Alloy) blocks (photo: MGA Thermal)
The E2S Power concept converts existing coal fired power plants into energy storage facilities by substituting the E2S thermal energy storage system for the boiler and integrating with existing
www.modernpowersystems.com | November/December 2021 | 31
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65
