Lithium-Ion Battery Applications
Lithium-ion batteries are constructed from materials that pose fire, explosion, and toxic exposure hazards. These batteries contain electrolyte systems that often include lithium hexaflourophosphate (LiPF6) as the electrolyte in a solvent like ethylene carbonate. Experience and studies show that these systems undergo self-accelerating decomposition and thermal runaway which leads to the generation of flammable gases, including CO, CH4, and C2H4, and toxic chemicals including HF and POF. In large scale (multi-cell) events large fires and even facility explosions have resulted due to accumulation of decomposition byproducts. Analysis shows that the amount of hydrogen fluoride (HF), which is extremely toxic with an immediately dangerous to life and health (IDLH) value of 30 parts per million (PPM), is sufficient to cause human harm if released in a small room, for battery systems as small as one that would be used in a single hybrid automobile.
Kenexis can help to safeguard facilities that utilize Li-Ion battery systems, such as automotive test and production facilities. The safeguarding begins with Process Hazards Analysis (PHA), through failure modes and effects analysis (FMEA) or HAZOP. This hazard analysis study will generally then lead to recommendations for safeguards. Common safeguards in Li-Ion battery systems include safety instrumented systems (SIS) to detect thermal runaway and “park” the battery in a state where the thermal runaway is stopped along with the potential addition of external cooling. If the battery system does go into thermal runaway it is important to safeguard people and the facility from the effects of the runaway. This is done be using gas dispersion analysis to place gas detectors that can indicate the extent and location of the hazardous situation and fire detection mapping to place optical fire detectors to provide an early warning of fire and allow mitigation actions to take place. The measurements from the fire and gas detectors can then be relayed to a SIS to take actions such as fire suppression and ventilation adjustments. Also, considering of the location of the hazard containing room in relation to normally occupied areas should be considered in a facility siting analysis.
Lithium-Ion Battery Development
Manufacturers of lithium-ion batteries must address hazards in their production process along with considering the liability of accidents experienced by their customers when using their products. Lithium-ion battery production facilities and processes should be assessed using PHA. The PHA will often lead to recommendations for a range of safeguards that include SIS and fire and gas systems. Storage of chemicals used in the production of the batteries should also consider the location of storage vessels and processes in relation to occupied rooms and buildings through facility siting.
Once the batteries are manufactured, testing and informing consumers of potential hazards and emergency response is essential for maintaining good relations. Li-ion batteries usually contain highly reactive chemicals whose decomposition can result in toxic chemicals release to the atmosphere. Testing should occur that allows users to understand what can go wrong and how to respond. This should include calorimetry testing that documents self-accelerating decomposition temperature (SADT), Temperature of No-Return (NRT), energy evolved by decomposition, reaction rate constants, and composition of materials released from decomposition. This information will then help large scale users of the batteries to appropriately safeguard their facilities with SIS and fire and gas systems.
Hydrogen Fuel Cell Applications
Generation of electricity from hydrogen fuel cells involves the hazards of hydrogen. Hydrogen if a flammable gas and, if confined, will readily explode if ignited. Hydrogen fires are particularly dangerous because they are not visible to the human eye. Facilities that employ hydrogen fuel cells should employ PHA to identify potential hazards. Gas dispersion modeling should be employed to identify any locations where a leak of hydrogen could accumulate and ignite, causing an explosion, and if identified gas detection systems should be employed. Also, fire detection mapping should be used to identify the required number and location of fires to detect and respond to any incidents of this “invisible” fire. Finally, facility siting should be employed to ensure that occupied rooms and buildings are sufficiently distant from any potential areas where explosion could occur.
Hydrogen Production and Storage
Hydrogen is a very important part of the green energy portfolio. It is abundant and can be produced from water. After consumption, either in traditional combustion or in a hydrogen fuel cell, the end product is water. Hydrogen can be produced in a variety of ways. Green hydrogen is produced in a carbon-free manner, typically by electrolysis of water. The electricity for the hydrolysis of to create green hydrogen would come from renewable methods such as wind and solar. Blue hydrogen, on the other hand, still relies on carbon-based fuels, specifically natural gas. Natural gas is consumed in a “steam reforming” process which generates hydrogen, but also generates carbon dioxide as a byproduct. Even though blue hydrogen is not the most desirable outcome from a “green” perspective, it is seen as an important steppingstone to get to that goal.
Hydrogen production involves the full range of hazards that are present in many chemical process facilities, including fire, explosion, and toxic hazards. Risk management begins with performing PHA on the process units and equipment that produce the hydrogen. Hydrogen generation units will rely extensively on SIS to protect the equipment (reactor, heater, compressors) and prevent loss of containment. Fire detection coverage mapping will likely need to be applied to place fire detectors, especially around high probability leak sources, such as compressors. Gas dispersion modeling is commonly required to place gas detectors, both for flammable such as the hydrogen product and natural gas feedstock, but also potentially toxic byproducts of carbon dioxide and carbon monoxide which can be especially problematic for indoor installations. Facility siting will be essential to keep potential consequences of process incidents from impacting occupied buildings, as hydrogen production facilities are generally quite large in scale.
Ammonia Production, Storage, and Transportation
Ammonia is not currently seen as a “green” chemical, but a traditional fertilizer, or worse yet, as a cleaning product. That is expected to change soon. The green energy possibilities of hydrogen are well known, but transportation and storage of hydrogen is difficult and potentially prohibitive. Ammonia is highly touted as a transportation and storage intermediary for the use of hydrogen. Hydrogen is readily converted into ammonia using mature process technology, and then stored and transported as liquid anhydrous ammonia, which has more than ten times the energy density of lithium-ion batteries and significantly more than compressed hydrogen. Once the ammonia reaches its destination it is then cracked back into nitrogen, which is returned to the air from whence it came and the hydrogen which can be used in fuel cells.
Ammonia production is mature and safe, but the hazards of flammability and toxicity are still present and must be managed. This management, as always, begins with PHA. SIS are commonly used in numerous locations in the process to protect equipment and prevent loss of containment. Since the process includes flammable materials and toxic materials. Gas dispersion modeling for gas detection placement is essentially, as is the protection of equipment against fire hazards through fire detection coverage mapping. Like all large industrial facilities that process chemicals, facility siting for ensuring appropriate separation of occupied areas from locations where fires, explosions, and toxic releases can manifest themselves is crucial.
An early green energy chemical, ethanol, which is generally created for motor fuels use through fermentation and distillation of corn, is currently widely used as a supplement to the pool of hydrocarbon-based motor fuels. As automobiles begin to move more toward electrification, through batteries or hydrogen fuel cells, it is expected that the use of ethanol as an energy source will taper off with the decrease in use of gasoline. Nevertheless, ethanol is commonly used today, and will be for the immediate and medium-term future.
Ethanol is a flammable liquid, which entails the same set of hazards as other flammable liquids. The ethanol production process will require performance of a PHA to understand the hazards that are present in the process equipment. Some use of SIS is warranted in the production of ethanol, especially if natural gas fired heaters are employed as the medium for reboiling distillation columns or production of steam. Fire and gas detection systems might be employed, but they are less relevant than in higher risk facilities. Ethanol, while flammable, is a liquid under ambient conditions and does not possess significant toxic properties through the inhalation route. Facility siting should be considered for ethanol production facilities due to the flammable concerns.
Another green liquid fuel is biodiesel/ biokerosene. These chemicals can be used as a substitute for diesel and kerosene that are produced with petroleum as the feedstock. These chemicals are expected to play a role in a green energy outlook for some time even after most automobiles get converted to electric. Diesel and kerosene are primarily used for heavy trucking and jets, respectively. These types of transportation require large amounts of very energy dense fuels, and there is no clear pathway to the large-scale use of electricity as a replacement energy mechanism in these services, especially airplane travel. Biodiesel and biokerosene are generated from a starting feedstock of fats (oils) that are generated by living organisms – plants or even algae. The fats are then broken down in process called transesterification to produce methyl esters (which are the final product) and glycerin. The production process, though, is significantly more complex, as there are a number of contaminants in plant oils that are not compatible the engines that will consume them or will result in environmentally undesirable byproducts of combustion. This additional treatment will include processes like hydrotreating for desulfurization and hydrogenation to saturate olefinic bonds in the ester’s hydrocarbon chain.
A biodiesel refinery that includes hydrogenation and hydrodesulfurization can be significantly hazardous. As one would expect, the beginning of process safety management for biodiesel is the PHA, which is expected to determine the need for SIS and fire and gas systems. Hydrodesulfurization occurs and high temperature and pressure and has a propensity for thermal runaway. As such, significant amount of SIS equipment is expected to be required. Also, since the process necessary utilizes hydrogen at high pressure, gas dispersion modeling for placement of gas detectors is expected, along with fire detection, especially in the vicinity of compressors. Also, the hydrogen required for desulfurization and hydrogenation will require all the same process safety management of any other hydrogen production facility, whether blue hydrogen (more likely) or green hydrogen (less likely). As always, facility siting needs to be considered when laying out the process equipment.