Sand Battery Patents

Sand battery (thermal energy storage, TES) patents cover storage-medium innovations; charging/heating innovations; insulation and long-duration innovations; and discharge, conversion, and process-heat innovations — with IP held by thermal-storage companies (in a field storing cheap renewable electricity as HIGH-TEMPERATURE HEAT in inexpensive solid materials, then delivering it as industrial process heat or re-converting it to electricity). WHY SAND BATTERIES / THERMAL STORAGE: storing energy as HEAT in cheap, abundant solids (sand, rock, refractory brick, graphite) is dramatically cheaper per kWh than electrochemical batteries for long-duration and especially for delivering HEAT — and industry needs vast amounts of high-temperature process heat (a huge, hard-to-decarbonize emissions source); a 'sand battery' charges by resistively heating the medium to high temperature with cheap/surplus renewable electricity, stores it for hours-to-days, then discharges heat (or electricity). MAJOR SAND-BATTERY / TES PATENT HOLDERS: POLAR NIGHT ENERGY: sand-based thermal storage (commercial installations in Finland for district heat). RONDO ENERGY: refractory-BRICK heat battery (RHB) for industrial heat/steam. ANTORA ENERGY: carbon/graphite blocks heated to very high temperature, discharged via THERMOPHOTOVOLTAIC (TPV) cells to electricity + heat. BRENMILLER (bGen crushed rock), ELECTRIFIED THERMAL SOLUTIONS (conductive e-bricks), MGA THERMAL (miscibility-gap-alloy blocks), KRAFTBLOCK. Storage media, charging/heating, insulation, and discharge/conversion are the core sand-battery patent domains — and high-temp media, efficient charging, long-duration insulation, and high-temp discharge/conversion are the open whitespace.

Storage-medium innovations; high-temperature-material innovations; charging/resistive-heating innovations; and thermal-cycling-durability innovations represent core sand-battery patent domains — and choosing a cheap medium that holds lots of heat at high temperature and heating it efficiently are the foundational levers. STORAGE-MEDIUM PATENTS: the solid that stores the heat — sand, crushed rock, REFRACTORY BRICKS (Rondo), graphite/carbon blocks (Antora), or engineered media like miscibility-gap ALLOYS (MGA — phase-change within a stable matrix for high energy density) — chosen for low cost, abundance, high heat capacity, high-temperature tolerance, and stability; the medium composition/structure is core IP. HIGH-TEMPERATURE-MATERIAL PATENTS: materials and structures that survive very high temperatures (500-1500°C) over many cycles without degrading, cracking, or reacting — refractory formulations, containment, and medium geometry for heat transfer. CHARGING / RESISTIVE-HEATING PATENTS: converting electricity to heat in the medium — resistive heating elements, CONDUCTIVE media that act as their own heater (Electrified Thermal's e-bricks pass current through the brick), inductive heating, and achieving high temperature efficiently and uniformly; the charging method/architecture is high-value. THERMAL-CYCLING-DURABILITY PATENTS: surviving repeated heat-up/cool-down (thermal expansion/stress, dust, sintering) over a 20+ year life — durability is essential. Cheap high-heat-capacity high-temperature media, conductive/efficient charging architectures, and thermal-cycling-durable materials are the highest-value medium/charging IP because the medium cost/temperature and charging efficiency determine storage economics.

Insulation and long-duration-retention innovations; discharge and heat-extraction innovations; electricity-conversion (thermophotovoltaic/turbine) innovations; and system, integration, and process-heat innovations represent additional sand-battery patent domains — and retaining heat over long durations and delivering it usefully (as heat or power) are where system value and differentiation sit. INSULATION / LONG-DURATION-RETENTION PATENTS: keeping the stored heat in for hours-to-days (or longer) with minimal loss — high-performance insulation, vacuum/multilayer insulation, containment design, and thermal management; low standby loss is what enables long-duration storage and is high-value. DISCHARGE / HEAT-EXTRACTION PATENTS: getting the heat back out controllably — passing air or fluid through/around the medium (heat exchange) to produce hot air/steam/process heat at the needed temperature, flow/temperature control, and matching industrial heat demand (Polar Night district heat, Rondo industrial steam). ELECTRICITY-CONVERSION PATENTS: re-converting stored heat to ELECTRICITY — THERMOPHOTOVOLTAIC (TPV) cells that convert the glow of very hot media to electricity (Antora), or steam/gas turbines/heat engines; the conversion method/efficiency is key for power applications. SYSTEM / INTEGRATION / PROCESS-HEAT PATENTS: integrating with industrial processes and grids — delivering high-temperature process heat (the biggest market), combined heat-and-power, grid services, controls, and modular/containerized systems. Long-duration low-loss insulation, controllable high-temperature heat extraction for industrial process heat, and efficient heat-to-electricity conversion (TPV/turbine) are the highest-value system IP because heat retention, useful discharge, and conversion efficiency determine what applications the storage can serve.

Sand battery startup IP strategy must navigate Polar Night/Rondo/Antora and thermal-storage portfolios, substantial thermal-energy-storage prior art (sensible-heat storage, refractory heat storage, and Cowper stoves/regenerators are old; molten-salt CSP storage is well-developed), the high-temperature-materials, insulation, and discharge challenges, the cost-per-kWh-thermal and round-trip-efficiency realities, the industrial-heat market focus, and a landscape where storage media, charging, insulation, discharge, and conversion are the durable assets; understand that storing heat in solids is an old concept, so the durable IP is in specific high-temp media, conductive/efficient charging, long-duration low-loss insulation, controllable high-temp discharge, and heat-to-power conversion (TPV), and that cost-per-kWh-thermal, temperature delivered, durability, and industrial integration matter as much as patents; identify whitespace in media, charging architecture, and high-temp discharge/conversion. SAND-BATTERY STARTUP IP STRATEGY: STORING HEAT IN SOLIDS IS AN OLD CONCEPT — MEDIA, CHARGING, INSULATION, AND DISCHARGE/CONVERSION ARE THE IP: sensible-heat/refractory storage is well-trodden, so patent specific media, conductive/efficient charging, long-duration insulation, and discharge/conversion methods — not 'store heat in sand'; STORAGE MEDIUM AND HIGH-TEMP DURABILITY ARE FOUNDATIONAL IP: the specific cheap, high-heat-capacity, high-temperature, cycle-durable medium (refractory brick, carbon, MGA alloy) is core composition/structure IP; CONDUCTIVE/EFFICIENT CHARGING IS HIGH-VALUE WHITESPACE: heating media efficiently to very high temperature (conductive e-bricks, resistive architectures) is a key differentiator; LONG-DURATION LOW-LOSS INSULATION ENABLES THE VALUE PROPOSITION: minimizing standby heat loss is what makes long-duration storage work — insulation/containment IP is valuable; HIGH-TEMP DISCHARGE AND HEAT-TO-POWER (TPV) ARE DIFFERENTIATORS: delivering high-temperature process heat controllably, and efficient thermophotovoltaic/turbine conversion to electricity (Antora), define application reach; INDUSTRIAL PROCESS HEAT IS THE BIGGEST MARKET (NOT JUST ELECTRICITY): industry's high-temp heat demand is huge and hard to decarbonize — targeting heat (vs round-trip power) is often the better thesis; COST-PER-KWH-THERMAL IS THE EXISTENTIAL METRIC: the whole point is being far cheaper than batteries for heat/long-duration — demonstrated low $/kWh-thermal strengthens patents and sales; WHEN TO PATENT: NOVEL MEDIUM/CHARGING/DISCHARGE WITH MEASURED PERFORMANCE: file once a medium/system shows measured results (cost ($/kWh-thermal) + storage temperature + energy density + standby loss/retention (duration) + charge/discharge efficiency + heat-to-power conversion efficiency (if applicable) + cycle durability) vs. molten-salt/battery baselines — measured $/kWh-thermal, temperature, and heat-retention duration are the critical sand-battery IP metrics; KEY FTO CHECKLIST: Polar Night Energy sand thermal storage; Rondo refractory-brick heat battery RHB; Antora carbon block + thermophotovoltaic; Brenmiller crushed rock bGen; Electrified Thermal conductive e-brick; MGA Thermal miscibility-gap alloy; storage medium sand/rock/refractory/graphite/alloy heat-capacity/high-temp/cost; high-temp material durability/containment; resistive/conductive/inductive charging architecture; thermal-cycling durability; insulation/vacuum/multilayer long-duration low-loss; discharge air/fluid heat-exchange process-heat/steam; thermophotovoltaic/turbine heat-to-electricity; industrial-heat integration/modular; sensible-heat/refractory/Cowper-stove + molten-salt-CSP prior art.