CO2 Liquefaction Temperature and Pressure: P-T Chart & Guide

CO2 liquefaction temperature and pressure define the specific conditions needed to convert carbon dioxide from gas into liquid form. Below 31.1°C and above 5.11 bar, CO2 can exist as a liquid, but the exact pressure required depends on temperature. At room temperature around 20°C, you need roughly 57 bar to keep CO2 liquid. Drop the temperature to 0°C, and pressure requirements fall to about 35 bar. These relationships follow a predictable curve on a pressure temperature chart, making it possible to design reliable storage and processing systems.

This guide shows you the exact temperature and pressure combinations that work for CO2 liquefaction. You'll find practical data for designing storage tanks, understanding the critical and triple points, and calculating the right operating conditions for your equipment. We cover how impurities change liquefaction requirements, safety margins you should build into your systems, and why these numbers matter for BioGas processing applications. Whether you're specifying a CO2 capture system or troubleshooting an existing setup, you'll get the technical details you need without wading through theory.

Why CO2 liquefaction conditions matter

Your liquefaction system's efficiency and safety depend directly on maintaining the right temperature and pressure combinations. Operating even 5 bar off target can increase your compression energy costs by 15-20%, turning a profitable operation into one that barely breaks even. Storage tanks designed for 20 bar can't safely handle 30 bar, and temperature swings of just 10°C can push your system past safe operating limits. These aren't theoretical concerns but real constraints that determine whether your equipment runs reliably or fails catastrophically.

Economic impact of operating parameters

The co2 liquefaction temperature and pressure you choose define your project's operating expenses for years. Lower storage temperatures around -20°C require only 20 bar pressure but need continuous refrigeration consuming 50-80 kWh per tonne of CO2. Higher pressure storage at 70 bar eliminates refrigeration costs but demands thicker vessel walls, increasing your capital expenditure by 30-40%. You'll find the sweet spot varies by project scale, local electricity costs, and whether you need to transport the CO2 afterward.

Temperature changes of just 5°C near the critical point can require pressure adjustments of 10 bar or more to maintain liquid phase.

Wrong conditions also mean lower CO2 purity in your final product. At insufficient pressure, you'll see partial vaporization that concentrates impurities in the liquid phase, potentially dropping purity below the 95% threshold that buyers require.

Safety margins and equipment longevity

Equipment ratings must account for temperature excursions during startup, shutdown, and upset conditions. Most industrial systems build in 10-15% pressure margins above normal operating conditions to handle transients without triggering relief valves. Temperature stratification in storage tanks can create local hot spots where pressure exceeds design limits even when average conditions look safe. Equipment cycling through freeze-thaw or pressure swings wears faster, shortening service life and increasing maintenance costs.

How to use CO2 P-T data in practice

You'll use pressure-temperature data every time you specify equipment, set control parameters, or troubleshoot a CO2 system. The relationship between co2 liquefaction temperature and pressure isn't just theoretical information but a direct input for calculating compressor stages, sizing relief valves, and determining insulation requirements. Engineering teams reference P-T charts dozens of times during design phases, and operators consult them daily to verify system conditions stay within safe boundaries. Understanding how to extract the right numbers from these charts separates functional designs from expensive failures.

Reading pressure-temperature charts

CO2 pressure-temperature charts plot pressure on the vertical axis and temperature on the horizontal axis, with curves showing phase boundaries. You'll see the vapor pressure curve running from the triple point at -56.6°C and 5.18 bar up to the critical point at 31.1°C and 73.8 bar. Any point above and to the left of this curve represents liquid conditions, while points below and to the right show gas conditions. Your operating point must sit comfortably within the liquid region with enough margin to handle upsets.

Find your target storage temperature on the horizontal axis, then trace vertically upward until you hit the vapor pressure curve. The pressure reading at that intersection shows the minimum pressure needed to maintain liquid phase. Add your safety margin (typically 10-15%) to this value to get your actual operating pressure. Charts also show lines of constant density, letting you calculate how much CO2 mass fits in a given tank volume at your chosen conditions.

Most P-T charts include both absolute pressure (bara) and gauge pressure (barg), so verify which scale you're reading to avoid 1-bar calculation errors.

Calculating operating windows

Your system needs defined upper and lower boundaries for both temperature and pressure to operate safely. Calculate the maximum allowable working pressure (MAWP) by adding your design pressure to the highest pressure you could see from temperature excursions, then compare this against your vessel's rated pressure. Temperature swings of ±10°C are common during daily ambient cycles, so trace these on your P-T chart to see how pressure will vary. If your storage operates at -20°C and 20 bar, a temperature rise to -10°C pushes pressure toward 24 bar automatically.

Process equipment upstream and downstream must handle the full range of conditions you'll encounter. Compressor discharge pressures need to exceed your storage pressure by 5-10 bar to overcome line losses and provide control margin. Pump suction conditions must stay far enough from the vapor pressure curve that no cavitation occurs, typically requiring 3-5 bar of net positive suction head.

Accounting for real-world conditions

Laboratory-pure CO2 follows published P-T relationships precisely, but your actual gas stream contains impurities that shift these curves. Nitrogen contamination above 2% can increase the pressure needed for liquefaction by 5-8 bar at a given temperature. Water content creates hydrate formation risks below 0°C that standard CO2 charts don't capture. You'll need to adjust published data based on your actual composition, often using process simulation software that accounts for multi-component mixtures.

Pressure drops through piping, valves, and heat exchangers reduce the pressure available at your storage vessel compared to compressor discharge. Calculate total system pressure drop including dynamic losses, then add this to your required storage pressure to determine discharge pressure needed. Elevation changes in your facility also matter because liquid CO2 creates hydrostatic head of roughly 0.8 bar per 10 meters of vertical height.

CO2 phase basics triple point to critical point

Carbon dioxide's phase behavior defines the exact boundaries where it transitions between solid, liquid, and gas states. You need to understand these fundamental limits because they determine what's physically possible in your liquefaction system. The triple point at -56.6°C and 5.18 bar marks the lowest pressure where liquid CO2 can exist, while the critical point at 31.1°C and 73.8 bar represents the highest temperature. Between these two boundaries, you'll find the operating window where co2 liquefaction temperature and pressure combinations keep your CO2 in liquid form. Outside this window, your CO2 will either freeze solid or exist only as gas or supercritical fluid.

The triple point boundary

Below the triple point conditions of 5.18 bar and -56.6°C, liquid CO2 cannot exist at any temperature or pressure combination. Your CO2 will transition directly from solid (dry ice) to gas through sublimation, skipping the liquid phase entirely. This explains why dry ice at atmospheric pressure (roughly 1 bar) never melts into a puddle but instead vaporizes directly into gas. Industrial systems must stay well above 5.18 bar to prevent accidental freezing that could plug lines, damage equipment, or create safety hazards from rapid pressure buildups when frozen CO2 warms and vaporizes.

Systems operating near the triple point face narrow margins between success and failure. Temperature drops of just 3-5°C below your target can push conditions into the solid region, while pressure losses through valves or fittings might drop you below the 5.18 bar threshold. You'll typically design with at least 2-3 bar margin above the triple point pressure to account for these variations.

The critical point threshold

At conditions above 31.1°C and 73.8 bar, CO2 enters the supercritical region where liquid and gas phases merge into a single fluid with unique properties. You can't liquefy CO2 above the critical temperature regardless of how much pressure you apply. Supercritical CO2 behaves like a dense gas with liquid-like dissolving power, making it useful for extraction processes but unsuitable for standard liquid storage and transport. Your liquefaction systems must keep temperatures below 31.1°C to produce true liquid CO2.

The critical point represents a hard boundary: above 31.1°C, compression alone cannot create liquid CO2 no matter how high the pressure goes.

Operating within 5°C of the critical temperature creates control challenges because small temperature changes cause large pressure swings. At 25°C you need 64 bar, but at 30°C you need 72 bar, an 8 bar increase from just 5°C of warming. Most practical systems operate at least 10-15°C below the critical point to maintain stable conditions.

Usable liquid range characteristics

Between the triple and critical points, you'll find the vapor pressure curve that defines the minimum pressure needed at each temperature. Lower temperatures along this curve require less pressure but need active cooling, while higher temperatures reduce refrigeration costs but demand thicker pressure vessels. Your system's optimal operating point depends on balancing these competing factors against your specific project economics and technical requirements.

Practical temperature and pressure ranges

Your actual operating conditions will fall into distinct ranges based on application, economics, and equipment constraints. Most industrial CO2 systems operate between -50°C and +20°C for temperature and 7 bar to 80 bar for pressure, though specific installations vary widely. These practical ranges represent proven combinations where equipment costs, energy requirements, and operational reliability balance against each other. You'll select from these established ranges rather than trying to operate at arbitrary conditions, because standardized equipment, safety codes, and industry experience cluster around specific temperature and pressure combinations that work reliably in real-world applications.

Low-pressure refrigerated storage

Storage systems operating at 7-20 bar pressure keep CO2 at temperatures between -50°C and -20°C to reduce vessel design pressures and wall thicknesses. You'll find this approach common in large-scale storage where the volume savings from thinner vessel walls offset refrigeration operating costs. Tanks at 7 bar and -50°C require continuous refrigeration consuming roughly 50-60 kWh per tonne of CO2, but the vessels cost 40-50% less than high-pressure alternatives at the same volume. Your refrigeration system must run constantly to maintain these conditions, making electrical reliability critical.

Lower pressures also simplify transport logistics since most road tankers and rail cars are rated for 20-25 bar maximum. Temperature maintenance becomes your primary operational concern, because ambient heat leakage of just 100 watts per square meter of tank surface can cause significant boil-off. You'll need insulation thicknesses of 200-300mm and active refrigeration with backup capacity to handle hot days and equipment failures.

Refrigerated storage at 7 bar and -50°C reduces vessel costs by 40-50% but adds continuous energy consumption of 50-60 kWh per tonne of CO2.

High-pressure ambient storage

Systems designed for 50-80 bar pressure can store CO2 at temperatures close to ambient conditions, typically +10°C to +25°C, eliminating refrigeration requirements. You'll pay more for thicker pressure vessels but save on operating costs since passive cooling through insulation and ambient air handles heat rejection. Storage at 70 bar and +20°C works well in moderate climates where summer temperatures don't exceed 30°C, keeping you safely below the critical point with adequate margins. Your capital costs increase 30-40% for the heavier vessels, but you eliminate 100% of the refrigeration energy consumption.

Pressure control becomes your key operating variable rather than temperature management. Ambient temperature swings of 10-15°C cause automatic pressure changes of 8-12 bar, so your vessel must safely handle the full range from coldest winter nights to hottest summer afternoons. You'll size relief valves and safety systems for peak conditions rather than average operating points.

Transport and intermediate conditions

Medium-pressure systems at 20-35 bar and -20°C to 0°C offer compromise solutions for applications requiring both storage and frequent transfer operations. Road tankers commonly operate at 20 bar and -20°C because these conditions balance vessel weight, cargo density, and refrigeration loads during multi-day transport. You'll achieve liquid densities around 1,000-1,100 kg/m³, maximizing payload while staying within vehicle weight limits. Loading and unloading equipment at terminals operates in this same range to maintain compatibility across the supply chain.

Your co2 liquefaction temperature and pressure selection in this range depends heavily on downstream requirements. Systems feeding pipeline injection need higher pressures (40-50 bar) to overcome line pressure drops, while those supplying dry ice production work better at lower pressures (15-20 bar) that reduce compression costs before the expansion process. Equipment in this intermediate range costs 15-25% more than low-pressure systems but uses 30-40% less energy than maintaining -50°C conditions.

Designing liquefaction and storage systems

Your liquefaction and storage system design starts with selecting target co2 liquefaction temperature and pressure conditions, then sizing every component to achieve and maintain those conditions reliably. Equipment specifications flow directly from your chosen operating point, determining compressor power requirements, vessel wall thicknesses, heat exchanger duties, and control system complexity. You'll make dozens of interconnected decisions where each choice constrains others, so starting with a clear operating philosophy prevents costly redesigns later. Systems designed around 20 bar and -20°C require fundamentally different equipment than those targeting 70 bar and +15°C, even though both successfully liquefy CO2.

Compressor staging and intercooling

You'll need multiple compression stages with intercooling to efficiently reach your target pressure while managing discharge temperatures. Single-stage compression from atmospheric to 70 bar would create discharge temperatures exceeding 250°C, damaging seals and wasting energy through excessive heat rejection. Most industrial systems use three to five stages with interstage cooling back to 30-40°C between each stage, keeping discharge temperatures below 120°C and improving overall efficiency by 25-35%. Your stage pressure ratios should stay between 2.5:1 and 4:1 per stage to balance equipment costs against compression efficiency.

Calculate total compression power by summing work across all stages, accounting for interstage pressure drops of 0.2-0.5 bar through coolers and piping. Typical power consumption ranges from 90-110 kWh per tonne of CO2 compressed from atmospheric to 70 bar, with lower values achieved through better intercooling and higher isentropic efficiencies. You'll reduce power by 8-12% for every 10°C reduction in interstage cooling temperature, making efficient heat rejection critical to operating economics.

Systems with optimized interstage cooling consume 25-35% less power than poorly designed compression trains reaching the same final pressure.

Vessel specification and materials

Your storage vessel design pressure must exceed your maximum operating pressure by margins defined in ASME Section VIII or equivalent codes, typically 125-150% of normal operating pressure. Vessels rated for 20 bar cost significantly less per unit volume than those rated for 70 bar because wall thickness increases roughly proportionally with pressure. Material selection depends on minimum design temperature, with carbon steel suitable down to -20°C, 3.5% nickel steel needed for -50°C, and austenitic stainless steel or aluminum required below -60°C to prevent brittle fracture.

Calculate vessel wall thickness using the formula t = (P × R) / (S × E - 0.6 × P), where P is design pressure, R is vessel radius, S is allowable stress, and E is weld joint efficiency. A 10 m³ vessel rated for 20 bar and -20°C might need 8mm carbon steel walls, while the same volume at 70 bar requires 25mm walls, tripling material costs. You'll also add corrosion allowances of 1-3mm and account for fabrication tolerances that increase actual thicknesses by 10-15%.

Nozzle locations, manway sizing, and internal configuration affect operational reliability and maintenance access. Bottom outlets work better than top takeoffs for liquid withdrawal because they prevent gas entrainment, while side-mounted level instruments give more reliable measurements than dip tubes that can freeze or plug.

Heat rejection and cooling systems

Heat loads in your system come from compression work, ambient heat ingress through insulation, and pump work for liquid transfer. Compression intercoolers handle the largest loads, rejecting 70-80% of compression work as heat at temperatures of 80-120°C that allow air or cooling water as heat sinks. Your refrigeration system (if required) removes ambient heat leakage plus any process upsets that warm the stored CO2, typically 0.3-0.8% of stored inventory per day in well-insulated vessels. Insulation thickness of 150-300mm reduces heat ingress to 50-150 watts per square meter of vessel surface, cutting refrigeration loads by 60-75% compared to uninsulated vessels.

Select cooling methods based on local conditions and economics. Air-cooled heat exchangers work in any location but face performance penalties above 35°C ambient, while water-cooled systems offer better performance where water supplies and disposal are available. Refrigeration systems for low-temperature storage require careful refrigerant selection, with ammonia, propane, or CO2 itself serving as refrigerants depending on temperature levels and local regulations.

CO2 purity and impurities impact

Your CO2 stream rarely arrives at liquefaction equipment as pure carbon dioxide, and these impurities directly alter the co2 liquefaction temperature and pressure relationships you've carefully calculated from standard charts. Even small concentrations of nitrogen, oxygen, or hydrocarbons shift the vapor pressure curve by measurable amounts, forcing you to increase compression power or decrease storage temperature to maintain liquid phase. Industrial CO2 sources typically contain 0.5-5% impurities depending on origin, with BioGas-derived streams often carrying higher contamination loads than combustion or fermentation sources. You'll find that ignoring composition effects leads to undersized compressors, inadequate cooling capacity, and product that fails downstream specifications.

Common contaminants and their effects

Nitrogen poses the most frequent challenge in BioGas applications because it doesn't condense at typical CO2 liquefaction conditions and accumulates in the liquid phase over time. Concentrations above 2% raise the pressure required for liquefaction by 5-8 bar at any given temperature, while levels exceeding 5% can double your compression costs. You'll see nitrogen content increase during storage as repeated pressure cycling causes it to concentrate, eventually requiring purge operations that waste captured CO2 and reduce system efficiency.

Oxygen contamination creates both operational and safety concerns, reacting with organic compounds in your gas stream to form acids that corrode equipment. Most industrial specifications limit O2 to below 10 ppm in liquefied CO2, requiring catalytic removal systems that add capital costs of $50,000-150,000 for medium-scale operations. Water vapor freezes at the low temperatures used in many liquefaction processes, forming ice or hydrate crystals that plug heat exchangers, valves, and instrumentation lines.

Nitrogen contamination above 2% can increase your compression power requirements by 15-20% while reducing liquid CO2 purity below acceptable limits for most commercial applications.

Sulfur compounds from BioGas digestion leave deposits on compressor valves and heat transfer surfaces, cutting efficiency by 10-15% over months of operation. Siloxanes from organic waste polymerize under compression heat, creating glassy deposits that require mechanical cleaning during unplanned shutdowns costing $10,000-30,000 in lost production.

Pressure and temperature shift from impurities

You'll need to adjust standard CO2 phase diagrams when your stream contains more than 1% total impurities, using process simulation software that calculates multi-component equilibrium. Binary mixtures of CO2 and nitrogen shift the vapor pressure curve upward by roughly 2-3 bar per 1% nitrogen at -20°C, while hydrocarbon contamination has less impact but still requires 1-2 bar additional pressure per percent. Your equipment must handle these higher pressures or accept lower storage temperatures to compensate.

Temperature effects become more pronounced near the critical point where small composition changes cause larger pressure deviations. Systems designed for 70 bar based on pure CO2 properties might actually need 78-82 bar when processing gas with 3-4% impurities, potentially exceeding vessel design limits. You'll see similar shifts in the opposite direction at lower temperatures, where impurities depress freezing points and create wider operating windows.

Purification requirements by application

Food grade CO2 demands purity above 99.9% with specific limits on individual contaminants, requiring multiple purification stages that add $200,000-500,000 to system costs. Enhanced oil recovery accepts 95-98% purity, letting you skip expensive polishing steps while still meeting injection well specifications. Your purification investment should match downstream requirements rather than chasing maximum purity that buyers won't pay for.

Pipeline injection typically requires 95% minimum purity to prevent corrosion and maintain flow properties, with some operators specifying 97-98% for longer pipeline life. BioMethane projects capturing CO2 for sale need to balance purification costs against market pricing, often finding the economic optimum at 96-97% purity where equipment costs plateau.

Safety and operational best practices

Your CO2 liquefaction system requires rigorous safety protocols because small operational errors can lead to rapid pressure buildups, catastrophic vessel failures, or personnel injuries from cold burns and asphyxiation. Operating pressures of 20-80 bar combined with temperatures as low as -50°C create multiple hazard scenarios that demand engineered safeguards and trained personnel. You'll face risks from overpressure events, cold liquid releases, oxygen displacement in confined spaces, and rapid phase transitions that can generate explosive forces. Industry statistics show that 60-70% of CO2 system incidents trace back to inadequate pressure relief sizing, insufficient operator training, or failure to follow established procedures during startup and shutdown operations.

Pressure relief and overpressure protection

You must install pressure relief valves sized to handle the maximum credible heat input scenario, typically calculated as total loss of cooling with full ambient heat ingress plus any process heat sources. Relief valve capacity should handle at least 110-120% of the maximum vaporization rate from fire exposure or cooling system failure, venting to a safe location away from personnel areas and ignition sources. Your relief system design needs to account for two-phase flow during venting because liquid CO2 flashing to gas creates much higher back pressures than gas-only venting, potentially reducing relief capacity by 30-40%.

Set pressure switches to trigger alarms at 90% of design pressure and initiate automatic shutdowns at 95% of maximum allowable working pressure. Redundant pressure instruments with independent power supplies prevent single-point failures that could leave you blind to developing overpressure conditions. You'll verify relief valve operation annually and test pressure switches quarterly to maintain reliability above 99.5%.

Relief valves must be sized for two-phase flow conditions during CO2 venting, as liquid flashing can reduce effective capacity by 30-40% compared to gas-only calculations.

Temperature monitoring and control

Your co2 liquefaction temperature and pressure controls need multiple independent temperature sensors at different locations in each vessel because stratification creates zones that vary by 5-10°C even during normal operation. Bottom temperatures typically run 3-5°C colder than top readings, so you'll control based on the warmest measurement to prevent overpressure while monitoring the coldest point to avoid freezing. Alarm setpoints should trigger at ±3°C from target to give operators time to respond before conditions reach safety limits at ±5°C.

Refrigeration systems require automatic switchover to backup compressors if primary units fail, maintaining temperature control within 2°C during the transition. Your control logic must prevent rapid temperature changes exceeding 10°C per hour that create thermal stresses in vessel walls and nozzles, potentially initiating fatigue cracks after repeated cycles.

Personnel training and emergency response

You need operators trained on CO2 hazards including cold burns from liquid contact, asphyxiation from gas accumulation in low areas, and high-pressure injection injuries from leaks. Training programs should include hands-on exercises with emergency shutdown systems, leak detection procedures, and proper use of self-contained breathing apparatus required for entry into potential oxygen-deficient atmospheres. Your facility must maintain oxygen monitors in areas where CO2 could accumulate, with alarms set at 19.5% oxygen and automatic ventilation activation at 18% oxygen concentration.

Emergency response plans need to address large-scale releases, equipment failures, and loss of utilities affecting pressure or temperature control. Practice drills conducted quarterly keep response teams sharp and identify procedure gaps before real emergencies occur.

Applying this to BioMethane projects

Your BioMethane facility faces unique challenges when capturing and liquefying CO2 because your gas stream composition differs significantly from industrial combustion or fermentation sources. BioGas typically contains 35-45% CO2 mixed with methane, plus contaminants like hydrogen sulfide, siloxanes, and moisture that complicate liquefaction operations. You'll need to account for these impurities when selecting co2 liquefaction temperature and pressure conditions, often requiring 5-10 bar higher operating pressures than pure CO2 systems to maintain stable liquid phase. Feed gas variability from changes in digester feedstock composition creates additional control challenges, demanding flexible equipment that handles composition swings of 5-10% without frequent adjustments or shutdowns.

BioGas composition impact on liquefaction

Raw BioGas from anaerobic digesters carries contaminants that standard CO2 phase charts don't account for, forcing you to build larger safety margins into your design. Hydrogen sulfide concentrations of 500-2,000 ppm create corrosion risks at the low temperatures used in liquefaction, requiring removal to below 4 ppm before compression to prevent equipment damage costing $20,000-50,000 in annual maintenance. Your siloxane content from organic waste sources deposits silicon dioxide on heat transfer surfaces when heated above 150°C, cutting heat exchanger efficiency by 15-20% between cleaning cycles. Moisture removal becomes critical because water content of 1-3% in raw BioGas forms ice crystals below 0°C, plugging control valves and instrumentation in systems designed for temperatures around -20°C.

BioGas-derived CO2 typically requires 10-15% higher compression capacity than combustion-source CO2 due to impurities that shift phase equilibrium and increase non-condensable gas content.

Integration with anaerobic digestion operations

You need to match your liquefaction system capacity to digester output patterns that vary daily and seasonally based on feedstock availability and ambient temperature effects on biological activity. Winter digester production often drops 20-30% compared to summer peaks, so your compression equipment should operate efficiently across a 3:1 turndown ratio rather than running at fixed capacity. Buffer storage between your BioMethane upgrading equipment and CO2 liquefaction system smooths these flow variations, letting you size compressors for average rather than peak loads and reducing capital costs by 25-35%.

Power availability at agricultural sites limits compression capacity, with many farms having only 200-400 kW electrical service that must support digesters, upgrading equipment, and CO2 capture simultaneously. Your total liquefaction power of 90-110 kWh per tonne of CO2 needs to fit within available capacity or justify upgrading electrical infrastructure that adds $100,000-300,000 to project costs.

Economic optimization for BioMethane facilities

Your optimal operating conditions balance equipment costs against ongoing expenses differently than industrial facilities because BioMethane projects operate at smaller scales where capital efficiency matters more. Storage at 20 bar and -20°C works well for farms processing 500-2,000 Nm³/hour of BioGas because vessels under 50 m³ cost only 15-20% more than atmospheric tanks while refrigeration loads stay below 50 kW. You'll capture CO2 at high purity (>99%) to maximize carbon credit revenue, with each percentage point of purity improvement worth $2-5 per tonne in environmental markets that reward verified emission reductions.

Key takeaways

You need to maintain co2 liquefaction temperature and pressure within specific boundaries defined by the triple point at 5.18 bar and -56.6°C and the critical point at 31.1°C and 73.8 bar. Your system's efficiency depends on selecting conditions that balance capital costs against operating expenses, with low-pressure refrigerated storage around 20 bar and -20°C offering different economics than high-pressure ambient storage at 70 bar. Impurities shift these requirements by 5-10 bar per percent of contamination, making purification essential for BioGas applications where nitrogen and sulfur compounds concentrate during liquefaction.

Design margins of 10-15% above operating pressure protect your equipment from upsets while multiple temperature sensors prevent stratification from causing overpressure incidents. Your compression system needs three to five stages with intercooling to reach target pressures efficiently, consuming 90-110 kWh per tonne of liquid CO2 produced. BioMethane facilities benefit from understanding these relationships to maximize carbon credit revenue while keeping capture costs competitive. Discover how 99pt5's BioTreater™ system integrates advanced CO2 capture with guaranteed 99.5% recovery rates for superior project economics.