Sand Battery Technology: A Promising Solution for Renewable Energy Storage[1][edit | edit source]
- Sand: abundant, inexpensive, available, Non-toxic
- sand-based electrodes--> store &release energy
- Use in small-scale residential systems to large-scale grid-level storage
- Adv:
- High energy density
- Long cycle life
- Cycle stability
- Safety
- Potential for renewable energy storage
- Sand-based electrodes--> potential in Li-ion & supercapacitors
- Sand-Based Energy Storage Technologies:
- Thermal energy storage.
- Mechanical energy storage.
- Electrochemical energy storage.
- Required materials:
- Sand
- storage medium
- should have high thermal conductivity
- low thermal mass
- withstand high temperatures
- Thermoelectric Generators
- Thermal energy in sand to electric energy (discharge: for electricity generation, power industry, space heating)
- selection: phase-change temperature & energy storage capacity.
- Electrodes/Heating Coil
- Transfer thermal energy between sand & the thermoelectric generator
- graphite or metal foils
- Insulation
- Reduce heat loss in charge & discharge
- Improves efficiency
- Heat Source:
- charge the battery & heat the sand
- Can be solar/ waste heat from industry/ renewable / nonrenewable thermal energy
- Container
- Holds everything
- withstand high temperatures & thermal stresses.
- Sand
- Design-->based on amount of required thermal energy & storage duration
- Energy generation & storage:
- wind / solar --> electricity
- 30%-->immediately power local infrastructure
- 70%-->store in sand battery & heat to 600-1000°C
- weaker solar--> use the stored energy
- Charge:
- Heat to sand--> increase temp --> until treshold-->full energy
- sand type & heat source--> different charge time
- Discharge:
- sand--> expose to a heat sink or device that extracts the heat
- sand temp drop-->energy release as heat
- Sand type & heat sink temp-->different discharge time
- Sand-battery type:
- Indirect Heat-Storing:
- heat transfer fluid (transfer heat to & from the sand)
- higher temp operation
- large physical footprint
- Direct Heat-Storing
- Direct contact with heat source & heat sink
- lower temperatures operation
- compact
- Thermochemical Heat-Storing
- chemical reaction
- store more energy
- longer charge & discharg time
- Hybrid Heat-Storing
- Combine of direct & indirect
- higher energy density
- faster charge & discharge
- Indirect Heat-Storing:
- Application
- Renewable Storage
- Heat & Cool
- Emergency Backup Power
- Challenges
- Efficiency --> depends on material/ design/ operating condition
- operating temp
- scale up
Sand Battery: An Innovative Solution for Renewable Energy Storage (A Review)[2][edit | edit source]
- UAE --> aims to use 7% of its energy from renewable sources (specifically solar)--> but challenging -->UAE deserts sand
- Sand composotion: silicon dioxide
- Subzero temp areas -->sand-bed-based solar heat/thermal storing promissing
- Dry sand-based TE--> High temp and high energy --> can be used in infrustructure of facilities like car parks
- Obtainable Materials: sand and rocks
- Installedcyclical storage structures: Germany, Canada, Turkey, Korea, the Netherlands, the United States, Finland, France, and Switzerland
- Sand: store up to 1000 °C, zero mass loss, reduced ownership and maintenance costs, improved and stable energy exchange rates
- sand medium: in a single basin solar--> increases the yearly mean of daily output by 23.8% (compared to no sand), hold the thermal energy for extended time, can be used during winter (when no solar available)
- Principle:
- 30% of the renewable used, 70% stored in sand --> increase temp to 600-1000
- Component of battery:
- steel casing--> sand & heat transmission piping
- External--> mechanical mechanisms, regulators, heat exchangers, fan
- Operation:
- Charge
- Storage
- Discharge
- Mechanism:
- Circulating hot air around sand --> Renewables control a resistance electric heater to increase the temp of the air near sand
- heat exchange tubing by a fan
- Dense insulation --> cover --> maintain temp
- Discharge: blow cool air--> heats up --> can steam water
- A COMPARISON OF DIFFERENT TES SYSTEMS TABLE AVAILABLE
- Disadv:
- Limited Temperature Range (300-1000)
- Slow Charge
- Low Power Density
- Land Use
- Transportation
- Recent:
- optimize particle size & distribution
- Application
- grid-level storage
- portable devices
- off-grid power systems
- industrial heating
- building heating
- district heating
- agriculture
- mining systems
Uses of sands in solar thermal technologies[3][edit | edit source]
- rock or mineral particles-->silica (quartz), feldspar, carbonates, micas, amphiboles, pyroxenes--> 0.06 to 2 mm in diameter
- 6% of land surface area (6% of the Earth land surface area in different regions)
- 2% North America
- over 30% Australia
- more than 45% Central Asia
- $11 and $58 per metric ton
- specific heat capacities: between 700 and 1000 J/kg◦C
- Thermal conductivity depends on porosity, granularity, moisture content, & mineralogy
- less porous-->higher thermal conductivity
- Smaller particles--> less thermal conductivity
- saturated with water --> higher thermal conductivities
- Quartz thermal conductivity: 7.7 W/m.K
- other sand constituents thermal conductivities: from 2.5 to 3.6 W/m.K
- non-toxic, non-corrosive, and non-flammable
- Sand in solar
- Thermal Energy Storage
- Solar Absorption
- Heat Transfer
- heat insulationsuitable
- large surface area --> water evaporation as evaporative medium
- Solar Distillation
- solar radiation --> obtain fresh water from impure water
- Limitation: low yield during the day and none at night
- with sand
- fill the area beneath the basin liner, the basin itself /using containers like metallic boxes, cotton bags, or mud pots
- maintain higher temperatures
- increase the evaporative surface area through capillary action
- fine, uniform sand better, black better, min thickness better, no water height above
- Solar heating
- Solar thermal collectors + thermal energy storage media
- High quartz content, low porosity, & high moisture content
- Dry sand with low quartz content
- Tank thermal energy storage
- Water: high specific heat capacity but Heat Loss --> Surrounding tanks with sands of low thermal conductivity; Sandy soil: lower heat capacity & thermal conductivity--> less heat loss from tanks compared to granite soil
- Require
- Low specific heat capacity and thermal conductivity
- Dry
- sufficient depth
- Aquifer Thermal Energy Storage (ATES)
- contain porous and permeable sand layers
- hot water in summer--> inject to the aquifer-->heat the soil and existed water--> extract the heat in winter, e.g. 72% recovery in Gassum Formation in Denmark
- Require
- High heat capacity and thermal conductivity
- High porosity and permeability
- Borehole Thermal Energy Storage (BTES)
- heat to ground by U-pipe heat exchangers in summer-->extract in winter
- high quartz low porosity sand --> good over bentonite or gravel
- 50% more heat for a 50% longer duration compared to gravel --> 78% efficiency
- Belgium: yearly storage efficiency 70%
- Require
- high thermal conductivity and heat storage capacity
- Packed-Bed Thermal Energy Storage
- use packed-bed sand in insulated pits
- 64% to 91% savings
- 65–75% of domestic hot water needs
- Finland
- Sand --> filled in containers or pits, heat transfer fluid flow through the bed--> Heat transfer in low demand (summer) & extract in high demand
- Require
- high thermal conductivity and specific heat capacity
- Solar Greenhouse Enhancement
- thermal storage walls (Trombe walls) --> increase air and soil temperatures in greenhouses
- made of: blackened surface (absorbs solar radiation, transferring heat to the sand), sand, and insulation
- greenhouses with sand thermal storage walls
- daytime air temp--> rise by 6.4°C above ambient, nighttime temp--> rise by 1.1°C
- Soil temp-->depth of up to 8 cm--> rise by 6.4°C during the day and by 4°C at night
- earlier flowering (by 14 days), earlier maturities (by 20 days), and higher yields (by 33.4%)
- Solar Dryers
- solar radiation --> dry agricultural or food products
- quartz, sand, gravel, soil minerals, sandstone, rocks, limestone, granite stone, soil, clay, waste concrete, fire bricks, and water
- sand:
- in drying chamber and the solar air heater--> reduce drying time & prevent the re-absorption of moisture at night
- increase the absorber surface area & roughness
- black-painted fine sand & high specific heat capacity & thermal conductivity
- Solar cooking
- Concentrating Solar Power (CSP)
- run a power block
- Which sand?
- Impurities in quartz (should be below 2%) --> less energy density
- Clays, carbonates, and feldspars--> agglomeration, degradation / reduced specific heat capacity
- Clays --> higher agglomeration at 600°C
- Carbonates --> decarbonization below 800°C--> mass loss & altered grain-size distribution
- Feldspars --> vitrify below 1200°C-->agglomeration --> impact on sand movement.
- Moderate cooling rates ~ 573°C required
- Below 1200°C --> quartz to cristobalite --> grain crack
- Solar gasification
- gasification: carbonaceous materials (like cokes, coal, biomass) --> fuels or chemicals
- Conventional methods: burning some of these raw materials --> heat generation for gasification --> loss of material & CO2 emission
- solar--> heat the material (no need to burn materials)----> quarts: receive, transfer & store heat & is inert (no reaction with materials) --> higher fuel quality & less carbon emission
- mix the carbonaceous materials with quartz --> solar is absorbs and transfers heat by sand --> raise temp (1100) --> thermal decomposition of carbonaceous materials --> syngas (synthetic gas) production
- require:
- High specific heat capacity and thermal conductivity
- Adiabatic Compressed Air Energy Storage
- Conventional: Excess electricity compresses air --> stored in underground--> natural gas required for reheat when required
- in sand: heat generated during compression --> store --> reheat compressed air when required by sand
- Charge: Hot air--> through heat exchanger --> sand flow in apposite direction --> sand warm, compressed air cold
- Discharge: cold compressed air--> through heat exchanger --> hot sand raise air temp
- electric cycle efficiency 69%
- High thermal conductivity and specific heat capacity
- Solar Photovoltaic/Thermal Panels
- PV-->small fraction of radiation to electricity --> excess to heat --> damage
- can be store in sand --> Cools down Pannels & prevent overheat
- e.g: desert sand and phase change materials (e.g., n-octacosane) --> Desert sand better heat transfer
- most suitable: high thermal conductivity and specific heat capacity
- Solar ponds:
- application:
- Industrial Process Heat
- Desalination
- Space Heating
- Power Generation
- Greenhouse Heating
- Salt Production
- Upper zone: low-salinity water--> insulator
- middle zone (Non-Convective Zone or Halocline) --> gradient of increasing salinity as depth increases --> density gradient--> convection currents prevention from forming -->traps heat in the lower layer
- Lower zone: high-salinity water-->Stores solar heat--> temp up to 85°C (185°F) or higher
- encasing sand in bottom and aournd lower layer --> reduce heat losses ( 69%) & store TE
- high thermal conductivity and specific heat capacity sand
- application:
- Solar-Powered Refrigerators:
- two metal cylinders --> sand-filled space between saturated with water
- solar --> power evaporation for cooling --> effective, accessible, sustainable
- Recommendation for research gaps:
- Coatings for Quartz Sand--> improve absorption, high mechanical wear & high temperatures up to 1000°C
Comparative CFD analysis of thermal energy storage materials in photovoltaic/thermal panels[5][edit | edit source]
- Desert sand (abundant, resistant to agglomeration, withstand high temperature) & silicon carbide --> enhanced heat transfer
- This study: copper pipe containing a water stream in a rectangular phase change material (PCM) exposed to solar, Additional absorber Layer
- under varying solar irradiance levels (ranging from 150 to 1,200 W/m2)
- desert sand: temperature of the liquid at the outlet boundary and the maximum temperature of the TES matrix are closer --> better heat transfer
- Relationship between the PCM solid fraction and the solar irradiance:
- Desert sand retains heat -->4,500 seconds after heat flux switched off
- n-octacosane retains for longer periods-->store and release heat over an extended period--> better for when heat release overnight required
Cost-effective Electro-Thermal Energy Storage to balance small scale renewable energy systems[6][edit | edit source]
- Assumes 100% conversion of electricity to heat
- quantity of electricity (P) needed to charge the energy storage: P=mCpΔT/t
- m: mass of the thermal storage material
- Cp: average specific heat capacity
- ΔT: temperature difference during charging
- t: time taken
- Thermal to electric = ηth*efficiency (efficiency in sand~85%)
- Heat rate = Power output /Thermal to electric efficiency
- Time for temperature decrease = Energy stored/ Heat rate
Materials (1.5 mᶟ) | Tmin (◦C) | Tmax (◦C) | Charging (kWh) | Discharging (kWh) | Efficiency |
---|---|---|---|---|---|
Thermal Oil | 180 | 410 | 192 | 84 | 44% |
Molten Salt | 200 | 500 | 372 | 118 | 32% |
Sand | 180 | 950 | 424 | 360 | 85% |
System/material selection | Quantity of storage material(kg) | Unit price | Total capacity | Base load capacity | Price in ($) | Systemcomponents cost $ | Total
designcost $ |
Storage cost $/kWh |
---|---|---|---|---|---|---|---|---|
ETES/Sand | 2446 kg | 0.25 $/kg | 359 kWh | 88 kWh | 672 | 24142 | 24814 | 69 |
Performance evaluation of a sand energy storage unit using response surface methodology[7][edit | edit source]
- Annual energy consumption: ~624,430 TWh
- Carbon footprint from fossil fuels: 36.7 billion ton
- Renewable energy demand in 2019: 6890.7 TWh
- Expected increase by 2,493 TWh between 2022 and 2025
- Types of TES Systems:
- Sensible Heat Storage: Simple and cost-effective.
- Latent Heat Storage: phase change materials.
- Thermoelectrical Storage: conversion between thermal and electrical energy
- Storage media:
- rocks, water, oil, salt
- Salt: Must be below 600°C
- Concrete Bricks: daytime, under 500°C, Temperature changes during discharge--> cycle effectiveness reduction
- SAND:
- High Thermal Capacity
- High Thermal Conductivity
- cost-effective
- Long-Term Stability
- Non-Toxic and Environmentally Friendly
- High-Temperature
- Optimum size for heat transfer 2–3 mm (larger: heat transfer effectiveness reduction, smaller: Increase in pressure drop-->larger heat exchanger volume)
- This Research:
- helical coil made of copper inserted inside a cylindrical tank
- Hot inlet fluid --> into the coil at temperatures up to 200°C
- Thermal Conductivity Measurement: KD2 Pro Decagon device with a TR1 single needle sensor type at 25°C
- Specific Heat Capacity Measurement: DSC-25, temperature range 25–200°C
- Specific Gravity Measurement: 1 kg of desert and beach sand, dried to constant mass (at 110 ± 5 ◦C) then add 6% moisture--> dry for 15-19 h.
- Experimental results:
- XRF
- Desert sand:13 elements, calcium 60.96%.
- Beach sand: 11 elements, calcium 86.9%.
- specific heat capacity
- increase with temperature
- Cp for desert-->higher
- dehydration of calcium hydroxide formed after heat treatment at 200°C
- Density
- Beach sand: denser
- scenario for simulation:
- Hot oil--> at 100°C & 0.01 m/s velocity--> heat transfer to 25°C sand, oil temperature decrease--> sand temperature and stored energy increase
- oil temp change --> increase sand temp and stored thermal energy
- oil velocity and coil turns increase--> stored energy increase
- total stored energy per kg of sand-->6.348 kJ/kg after an 8h charging .
- pressure drop -->71.4 Pa
- desert sand Thermal conductivity -->higher than beach sand by 1.77%
- Thermal resistivity of beach sand -->29.3% higher compared to desert sand
- XRF
Improved effective thermal conductivity of sand bed in thermal energy storage systems[8][edit | edit source]
- Introduction:
- TES--> substitute for lithium-ion batteries in stationary electric-grid storage
- Sand--> high thermal tolerance (melting point around 1700°C)
- wide temp range-->Enhanced Carnot cycle efficiencies
- sand High specific heat capacity --> high energy density BUT granular form & point contact between grains -->low thermal conductivity
- Coating of quartz sand --> improve solar absorption & thermal stability & enhancing energy storage efficiency by 60% to 80% compared to raw sand
- thermal conductivity of bentonite sand--> increase by add granite powder
- common methods-->Direct solar heating and heating by fluidisation (Circulating heat transfer fluids through heat exchangers in sand-packed beds)
- Mixing different heat storage materials--> improve storage properties
- Waste material streams-->economical materials option
- cut metal scrap from Metal workshops --> circular economy
- This research:
- Rectangular aluminium container (height 380 mm, length 230 mm, width 380 mm) --> investigate thermal properties of sand bed
- Two tubular-type resistance heaters (height 298 mm, width 309 mm, diameter 50 mm)--> 95 mm apart in the center of the box--> 2 kW On/Off control box & temp regulation up to 1000 °C
- K-type thermocouples --> between heaters (45 ±0.7 mm from each heater) and 30 mm away from heaters
- Sand bed -->exposed to air (T below 26 °C) without insulation
- Combination of sand and metallic by-products (enhance thermal conductivity)
- Brown Silica: silica (SiO2), grain size 0.06 to 0.2 mm, melting point 1713 °C, specific heat capacity 703 J/(kg⋅K), thermal conductivity 0.2 to 0.7 W/(m⋅K), bulk density 1800 kg/m3
- aluminium:15 to 20 mm long, 0.5 mm thick, 1.5 mm wide, melting point 660 °C, specific heat 897 J/(kg⋅K), thermal conductivity 205 W/(m⋅K), density 2712 kg/m3
- brass:diameter 0.25 mm, length 4.5 mm, melting temperatures 900 to 940 °C, specific heat 380 J/(kg⋅K), thermal conductivity 113 W/(m⋅K), density 8430 to 8730 kg/m3
- mixed metal chips: 90% steel, 10% aluminium/ length 10-15 mm, thickness 0.5 mm, breadth 1.5 mm/ Tm: 1370-1540 °C/ specific heat 490 J/(kg⋅K)/ thermal conductivity 50-70 W/(m⋅K) (varies by alloy)/ density: 7850 kg/m³
- T4: between wall and electric heater/ T3: between two electric heaters
- surface temperature reaches 500 °C within 30 min
- T4: heat faster than T3 in first 75 min (17.5 mm closer to heat source) & temperature constant at 350 °C after 3 h & rapid temperature decline outside heating elements
- T3: hotter than T4 after 80 min, equals surface temperature of heaters after 7 h & less rapid heat loss to environment & heat trap/ low thermal conductivity, high heat capacity of sand --> Terminal lag in T3
- Sand conductivity: 0.114 W/(m⋅K)
- Simulated charging time: five hours
- Brass-sand layer: highest effective thermal conductivity/ higher density and less porous structure--> lower thermal conductivity than aluminium
- Aluminium chips:
- More effective in uniform mixture: high thermal conductivity
- 20% aluminium: heat rate 1.7 times of pure sand & increases stable T4 temperature --> higher effective thermal conductivity
- 10% and 5% aluminium heat rates 1.36 times and 1.18 times of pure sand
- Higher aluminium:increased percolation & more interconnections --> facilitate heat transfer
- Lower chip concentrations: isolation of chips, fewer conductive paths, & lower thermal conductivity
- enhances overall temperature gradient of sand bed
- mix-metal chips--> lower performance: higher steel content (lower thermal conductivity)
- temperature outside thermocouples: metal composite--> Higher temperature than pure sand
- Metallic chips: easy heat travel--> more storage
- Commercial scrap metal prices in Finland--> Aluminium: 0.7 & Brass: 3.1 & Stainless steel: 0.7
From waste to value: Utilising waste foundry sand in thermal energy storage as a matrix material in composites[9][edit | edit source]
- Introduction:
- Waste foundry sand (WFS) by-product of metal casting processes
- WFS characteristics: ceramic composition, density, particle size (0.15 mm < D < 0.6 mm), specific surface area
- WFS recycling pathway: key material for composite phase change materials to capture, store, reuse waste heat
- This research:
- Materials:
- NaNO3, natural materials including clay, fully recyclable, Bentonite in sodium form, waste foundry sand (CPCM matrix material, predominant component: SiO2 at 87.91%, secondary components: Al2O3 at 4.7%, Fe2O3 at 0.94%), Additive X (?)
- Fabrication:
- Comminution with mortar and pestle (85–95% between 0.6 mm and 0.15 mm uniform grain size distribution)
- Hand-stirring mixture
- Shaping into 13 mm pellets under 60 MPa pressure for 2 min
- Sintering at 400 °C, 5 °C/min in high-temp
- Cooling to room tempe for shape-stable structure
- Poor cohesion at 70–30 (WFS-salt) mass ratio -->instability
- Additive X (?):
- Thixotropic properties form gel-like matrix with water--> improving WFS particle binding
- Increases CPCM resistance to stresses during phase change process
- Tests:
- Sand grain density: Helium-based pycnometer, 2.51 ± 0.06 g/cm³
- Bulk density: Mass and volume (dimensions) of individual pellets, Porosity deduced from density ratio
- Latent heat, melting point, specific heat capacity: DSC: Temperature range: 20 to 400 °C, ramping speed: 10 °C/min, Aluminum crucibles, ambient air environment, gas flow rate: 100 ml/min, sapphire method for specific heat
- Thermal conductivity and diffusivity: Laser Flash Technique, Level sample surfaces, graphite spray coatingAirflow setting: 100 ml/min, Thermal conductivity formula: λ = a(T)ρ(T)Cp(T)
- TGA: Sample weight: ~10 mg, platinum crucible, Temperature range: 25 to 500 °C, heating rate: 10 °C/min, ambient air
- Microstructure and pore size distribution: X-ray nano-CT, Cylindrical samples: φ 2 × 15 mm, Voltage: 95 kV, current: 150 μA, pixel resolution: 9.5 μm, Projection images at 0.1° intervals, 180° rotation, Data analysis: Recon software, CTan software
- Coefficient of thermal expansion: Optical dilatometer, Cylindrical samples: ~13 mm diameter, Heating: ambient temperature to 500 °C, rate: 5 K/min, air environment
- Compressive strength
- Thermal cycling protocol: Temperature increase to 400 °C, hold for 30 minutes, Temperature decrease to 270 °C, hold for 10 minutes,Total of 48 cycles, Structural resilience and thermal efficacy assessment of WFS-salt CPCMs
- ..... (discussion)
- Energy storage density: 628 ± 27 kJ/kg for Na60, 567 ± 43 kJ/kg for Na55
- Average thermal conductivity: 24% higher for Na60 (1.38 W/mK) than Na55 (1.08 W/mK), due to higher porosity of Na55
- Compressive strength: 141 MPa for Na60, 105 MPa for Na55, influenced by porosity and pore size
- Larger porosity beneficial for CTE of CPCM
- Materials:
Heat Storing Sand Battery[10][edit | edit source]
- Desert sand can store thermal energy up to 1000 ℃
- 400 ℃ higher than molten salt
- Molten salt:
- maintenance to avoid plugging
- External heat needed to maintain temp above 260 °C
- 28,000 tons --> for 7.5 hours of storage
- 25.2 million dollars for storage medium
- This research:
- Electric heater chosen as heat input
- Heat by heater -->to heat exchanger through Heat Transfer Fluid (oil)
- Oil -->in an oil tank, pumped through pipes to heat exchanger
- Temp sensors--> monitor sand temp change
- Charging: Sand heated to desired temperature (150 °C)
- Storing: sand thermal energy retention over time
- Discharging:
- Cold oil -->through pipes to absorb sand heat
- Thermoelectric generator--> thermal energy to electrical energy
What Is a ‘Sand Battery’?[11][edit | edit source]
- First commercial sand battery: In Kankaanpää, Western Finland (max temp:600 ℃, can be higher though)--> integrated into a district heating network operated by Vatajankoski (Green energy supplier)
- In residential and commercial buildings (homes & swimming pool)
- Structure:
- Insulated silo of steel housing filled with sand & heat transfer pipes.
- Automation components, valves, a fan, & heat exchanger or steam generator.
- Heating:
- Electricity from the grid or local production from wind and solar.
- Charged during periods of clean and cheap electricity availability.
- Electrical energy -->heat air with electrical resistors --> via a closed-loop air-pipe--> circulate it through heat transfer piping--> to heat storage
- Extraction:
- Blowing cool air through pipes--> heat up
- used to convert water into process steam / heat district heating water in an air-to-water heat exchanger.
- Stay hot for months, typically charged and discharged in 2-week cycles
- Best range of use when charged and discharged 20 to 200 times per year
- In "Polar night energy":
- 600 °C, 10GWh, 100MW
- 36% of industrial heating demand can be provided by sand battery (now is relying on oil and gas)
- can save 100 Mt/year carbon mono oxide in 2030
- can supply power for about 10,000 people
- 30% of solar/wind--> direct use, 70% stored as heat, less than 10% need for external energy for the whole year
Climate change: 'Sand battery' could solve green energy's big problem[12][edit | edit source]
- Finland long border with Russia and halted gas and electricity supplies due to Finland joining NATO -->Concerns over heat and light sources during long, cold winters
- World first fully working sand batteryinstalled by Finnish researchers-->developed by "Polar Night Energy"
- power plant in western Finland --> 100 tonnes of sand inside a grey silo
- Difficulty in efficiently converting stored heat back to electricity.
Sand Battery For Thermal Storage[13][edit | edit source]
- Batsand: Thermal battery with heating generator and sand vessel.
- bring hot and fresh sand directly to the home
- Charge (with solar panels) in summer--> heating / cooling when needed
- potential to return investment in 4-6 years
- combine with solar panel --> Can disconnect from grid
- Rated Power: 1:14 KW, 2: 25KW
- Battery Capacity: 1: 12000 KWH, 2: 21000 KWH
- Suitable Home Size: 1: 300-600 m², 2: 500-1200
- Size: 1: 140 cm x 72 cm x 55 cm, 2: 185 cm x 85 cm x 72 cm
- Weight: 1: 142 Kgs, 2: 174 Kgs
How a Sand Battery Could Revolutionize Home Energy Storage[14][edit | edit source]
- University of Michgan: 30% of total US residential enery use--> dedicated to heating (water heating:13%)
- US Lawrance Berkeley National Laboratory: 1/5 of energy produced in US--> building thermal load
- DraKE landing solar community-->2012: 96%, 2015, 2016: 100% of their yearly heating from solar
- TES: good round trip efficiency (RTE) rates (% of electricity into storage)--> 100% RTE: every stored energy can be used; thermodynamically impossible
- lead acid:70%, Li ion: 90%
- sand: low specific heat, high density: large storage of thermal, no chemical reactions: no maintanace, above boiling water
- heat sand with solar-->move to home with air
- challenge: size--> Batsand ($7700-increase to $19000 with installation, store energy at 92% efficiency with 94% RTE) is in small size (40m^3), under ground-->300-400 m^2 building, 10680 kW/h with +30 kW solar
- Newton Energy Solution (NES) ($5300-6400, 95% RTE)--> between TES & water heater & buffer tank--> water heater already a TES (but can't turn heat to electricity) water volume of 590 mm x 1650 mm (214 L)--> 20 kWh (can heat 600 L tap water to 40 °C &, 320 L--> 29 kWh
- the efficiency drop to 50-70% when heat to electricity
DIY Sand battery HEATER. Over 599f simple to make[15][edit | edit source]
- Equipment:
- 30 L steel tub
- water heating element--> 300W 12v
- hardware sore sand (play sand)--> 5-8 kg
- ventiliser is required
- watt meter
- Method:
- Fill half way
- put element in center
- connect the w meter to the element wire
- in 40 min--> 179°C, in 50 min--> 290 °C
Sand Energy Storage System for Water Heater[edit | edit source]
- Demand for new and effective storage materials.
- Use of sand, abundant in Jordan, as a storage material.
- Silica sand predominant in southern Jordan, comprising 95.5% to 98.31% SiO2
- Specific heat capacity of silica sand: average 830 J/kg°C
- Energy stored proportional to temperature rise, specific heat capacity, and mass of medium.
- Solar Radiation in Jordan:
- Yearly average: 2080 kWh/m2.
- More than 300 sunny days annually.
- Average daily radiation: 5.7 kWh/m2, with 8 hours of sun.
- June and July have highest sun hours (almost 12 hours) and radiation values (8.2 kWh/m2).
- December and January --> least sun activity ( 5 hours/day) and lowest daily radiation (2.9 kWh/m2).
- Optimizing inclination angle between 10° and 60° increases yearly radiation to 2419 kWh/m2.
- Most economical and effective inclination angle for PV system installation in Jordan: 30°.
- Yearly radiation at this angle: 2330 kWh/m2.
- Jordan Weather:
- Hottest month: July (average temperature 25°C/77°F).
- Coldest month: January (average temperature 8°C/46°F).
- Temperature fluctuation parameters: between 31°C and 4°C throughout the year.
- Rare cases of extreme temperatures: up to 43°C and as low as -10°C in different regions of Jordan.
- Energy storage design for night use as water heating source.
- Standard hot water temperature: 70°C.
- Average hot water use per person in Jordan: 40 liters/day.
- Average household size in Jordan: 5 people.
- Total water to heat: 200 liters (rounded to 240 liters).
- Water mass: 240 kg.
- Specific heat of water: 4.186 kJ/kg°C.
- Required temperature: 80°C (including error).
- Min temperature in January: 5°C.
- Temperature difference (∆T): 75°C.
- Energy required (Q):
- Q=m×Cp×ΔT=240kg×4.186kJ/kg°C×75°C=75,348kJ
- Least sun hours per day in December: 5 hours.
- Least average solar radiation per day in December: 2.9 kWh/m².
- Energy demand: 75,500 kJ --> 20.98 kWh.
- Silica sand
- Thermal conductivity: 0.33 W/m°C.
- Average thermal heat capacity: 0.83 kJ/kg°C
- ∆T: 75°C
- m=Q/Cp×ΔT-->m=1,213kg.
- Density of silica: 1,522 kg/m³ --> V= 1 m3
- System Design
- Storage tank
- Heat exchanger
- D= 60 cm & H= 0.9 m
- inlet top, outlet bottom
Solar Power Calculator for London, Ontario, Canada[16][edit | edit source]
- yearly avg of solar radiation in London Ontario: 1547.32 kWh/m2
- avg daily radiation: 4.232 kWh/m2
- Months of highest sunny days: June 9.6h & 6.08 kWh/m2, July 10.1h & 6.11 kWh/m2
- Least sun activity: Jan 2.3h & 1.97 kWh/m2, Dec 2.7h & 1.67 kWh/m2
Climate and monthly weather forecast, London, Canada[17][edit | edit source]
- Avg temp in hottest month: 25.5
- Avg temp in coldest month: -8.2
- ↑ Sand Battery Technology: A Promising Solution for Renewable Energy Storage
- ↑ Sand Battery: An Innovative Solution for Renewable Energy Storage (A Review)
- ↑ Uses of sands in solar thermal technologies
- ↑ http://dx.doi.org/10.1016/B978-0-12-818634-3.50133-8
- ↑ Comparative CFD analysis of thermal energy storage materials in photovoltaic/thermal panels
- ↑ Cost-effective Electro-Thermal Energy Storage to balance small scale renewable energy systems
- ↑ Performance evaluation of a sand energy storage unit using response surface methodology
- ↑ Improved effective thermal conductivity of sand bed in thermal energy storage systems
- ↑ From waste to value: Utilising waste foundry sand in thermal energy storage as a matrix material in composites
- ↑ Heat Storing Sand Battery
- ↑ https://polarnightenergy.fi/sand-battery
- ↑ https://www.bbc.com/news/science-environment-61996520
- ↑ https://www.batsand.com/
- ↑ https://www.youtube.com/watch?v=KVqHYNE2QwE&t=62s
- ↑ https://www.youtube.com/watch?v=4uUwMaiY12M
- ↑ https://solarcalculator.ca/report/Ontario/London/#:~:text=To%20navigate%2C%20press%20the%20arrow,panel%20slope%20of%2034o.
- ↑ https://www.weather-atlas.com/en/canada/london-climate