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The provision of heat from MWh thermal batteries using phase change materials charged by renewable electricity during off peak time to provide heat for district heating networks.
About
Low carbon heat, this is what Sunamp thermal battery can offer to help National Grid decarbonizing the access of heat, by deploying tens to hundreds of MWh thermal battery storage on district heating networks around the United Kingdom and in the United States (we have an active US subsidary). With a system that includes a renewable energy source, a heat pump or an electric resistive boiler, a Sunamp bank of thermal batteries and a connection for a district heat network, the heat can be supplied for thousands to millions of customers by a low carbon solution. The thermal batteries offer a low carbon solution by running the charging equipment (heat pump or electric boiler) during the peak of renewable production or during off-peak time to store thermal energy to be used during peak time, which increases resilience by assisting the grid to balance the load by not fully depending on the grid to keep increasing electricity generation to deliverheat to the properties. .
Sunamp thermal battery differs from the other types of storage by being based on a phase change material. This material stores thermal energy instead of electrical energy, in the latent heat of the phase change. Sunamp thermal batteries have two materials at the correct temperature. These are as follows Plentigrade P58 that change phase at 58°C which is suitable for 4th generation heat networks and Plentigrade P89 that changes phase at 89°C, which is suitable for traditional 3rd generation heat networks. The phase change material comes from sustainable supply chain, is non-flammable, non toxic, recyclable and is designed and tested to operate at least 25 years with no minimum maintenance required. A whole solution that can be on the field for a long time.
The key innovation of the solution is the Sunamp thermal batteries that use phase change materials (PCM) to store energy for domestic hot water, heating, steam, and cooling applications. Background to the high level technical information is as follows. The Plentigrade pcm can can store 3-4 times as much energy in latent heat as the sensible heat of water in a typical thermal storage (i.e., thermal buffering) applications.
The generic construction of the battery includes the PCM, and the heat exchanger housed in a sealed enclosure (The Cell). Although the Cell is sealed against ingress of moisture and air, the pressure inside the Cell is around the ambient atmospheric pressure and is fitted with an expansion relief valve. The Cell is insulated using vacuum insulation panels. The outer case and hydraulic connections are designed so that multiple batteries can either be stacked or positioned side by side and then connected either in series or parallel. The polypropylene container containing the heater exchanger is filled with the appropriate phase change material that is prepared in a mixing tank. Sensors and wiring are connected to the controller that sits within the overall casing.
Compared with conventional PCM and water based thermal stores, the Sunamp thermal battery technology has the following advantages:
a) High flow rates and power ratings (heat exchanger immersed in PCM)
b) Additive to PCM and internal design of heat battery eliminates sub-cooling
c) PCM Raw materials: Made from by-products of widely deployed industrial processes, non-toxic, and based on inorganic salts, which are non-flammable and with low stable commodity pricing.
d) PCM costs < $0.5/kg; complete heat batteries cost under $65/kWh.
e) Strong focus on corrosion and permeability (water/ oxygen ingress), resulting in confidence in long lifetime. Over 95% capacity remains after 40,000 accelerated cycles.
f) Very low water content, lower water treatment costs, and additional expansion vessels not required. (90 kWh battery has only 70 Litres of water inside).
g) Unlike a hot water thermal store, the aspect ratios of Sunamp Heat Battery can be changed without compromising, storage capacity, utilization efficiency and stratification.
h) Over 80% of thermal energy is stored in the PCM and the PCM enclosure is at near atmospheric pressure and therefore safety devices associated with pressurised hot water stores will not be required.
i) Two independent hydronic circuits, which can be combined where separate and/or simultaneous charging and discharging is not required.
Compared with conventional commercial electrical storage, Sunamp have the following advantages:
a) Lifespan tested for over 40.000 cycles (50 years when cycled 2 times/day).
b) Sunamp batteries can be charged from multiple thermal sources including boilers, heat pumps, waste heat, electricity (grid or embedded), steam, glycol/water, thermal solar panels and recovered heat.
c) At least 2.5 times cheaper than an electric battery.
d) Non-flammable substances in the PCM composition.
e) Non-toxic substances in the PCM composition.
f) Derived from sustainable supply chains.
Key Benefits
A low carbon heating solution that can be applied in multiple neighborhoods helps to maximize the usage of renewables, and a better usage of the energy from the electricity grid, reducing the peak demand. It allows heat to be produced when conditions are favorable and used on demand. It also allows district heating plants to downsize heating equipment (electric boiler, heat pumps), in this case the storage is charged for a continuous period, reducing recycling operation, which improves energy efficiency, reduces capital costs, and increases grid resilience. When the energy usage is decoupled from the generation, more resilience is seen by decompressing the grid for community benefit.
Benefits to Customers:
• Higher energy efficiency
• Lower building costs (no separate boilers, chillers, or other related hardware)
• Easier building operation and maintenance
• Enhanced building aesthetics and comfort (reduced noise and vibration)
• Improved reliability (industrial-grade district energy equipment is more robust than commercial equipment installed at building level)
Benefits to Cities and Communities:
• Reduced first cost for new development
• Flexibility in use of renewable sources
• Architectural and aesthetic advantages, with roofs free of mechanical equipment and smaller thermal storage containment i.e. no need to have very large and visually imposing stratified hot water tanks.
• Capacity to provide baseload power and heat for microgrids, enhancing resilience and reducing regional greenhouse gas emissions
Benefits to Grid Infrastructure:
• Reduced peak demand by aggregating loads and shifting peak demand with thermal energy storage
• Fewer natural gas peaking stations
• Lower transmission and distribution costs by centralizing production in local plants
• Balancing of the grid
• Lower cost for grid reinforcement
• Dispatchable thermal storage
Benefits to the Environment:
• Reduced CO2 emissions, by making a better usage of the renewables
• Increased adoption of renewable energy sources at scale, replacing higher-emitting central station generation with low- and zero-emitting technologies
Applications
In the UK the system can be applied for medium temperature networks for new build properties connected to 4th Generation heat networks using a 55°C network serving both space heating and DHW. Since DHW is not stored in thermal storage that uses phase change materials, this does not pose a problem for legionella growth. It can also be applied in networks that use a 45°C network for space heating, separate from a second (gas boiler based) system to serve the DHW demand.
The district heating network solution using Sunamp thermal storage can be applied worldwide, especially in regions where excess renewable energy is produced and the company wants to reduce carbon emissions in the system. Sunamp thermal battery offers resilience and low carbon solution with an easy integration and compact way, storing 8MWh of thermal energy in two 20-foot shipping containers, maximizing the usage of renewables and reducing the peak demand on the grid. Thermal storage allows heat to be produced when conditions are favorable (off-peak) and used on demand, allowing the utility to control the energy usage by managing the storage charging periods.