Re: [TUHS] Death by bug

Hi Jon, I see, a ‘big bang’ disaster, like Bhopal, rather than a gradual sniping. There's the Battery Management System software which controls the charging and discharge of Lithium-ion batteries. I don't mean a burning laptop causing an airliner to go down, more a shipping container stuffed full of the things going up. There is an interesting recent paper on the flaws in ‘Battery Energy Storage Systems’ and defending against the inevitable lithium metal dendrites. It assumes the BMS has no flaws but if it did then the same end effect could occur. Here's some extracts from the ‘Executive Summary’. Safety of Grid Scale Lithium-ion Battery Energy Storage Systems https://www.researchgate.net/publication/352158070_Safety_of_Grid_Scale_Lit… Li-ion batteries are dominant in large, grid-scale, Battery Energy Storage Systems (BESS) of several MWh and upwards in capacity. Several proposals for large-scale solar photovoltaic (PV) “energy farms” are current, incorporating very large capacity BESS. Despite storing electrochemical energy of many hundreds of tons of TNT equivalent, and several times the energy released in the August 2020 Beirut explosion, these BESS are regarded as “articles” by the Health and Safety Executive (HSE), in defiance of the Control of Major Accident Hazards Regulations (COMAH) 2015, intended to safeguard public health... Li-ion batteries can fail by “thermal runaway” where overheating in a single faulty cell can propagate to neighbours with energy releases popularly known as “battery fires”. These are not strictly “fires” at all, requiring no oxygen to propagate. They are uncontrollable except by extravagant water cooling. They evolve toxic gases such as Hydrogen Fluoride (HF) and highly inflammable gases including Hydrogen (H2), Methane (CH4), Ethylene (C2H4) and Carbon Monoxide (CO). These in turn may cause further explosions or fires upon ignition. The chemical energy then released can be up to 20 times the stored electrochemical energy. “Battery fires” in grid scale BESS have occurred in South Korea, Belgium (2017), Arizona (2019) and in urban Liverpool (Sept 2020)... A report into the Liverpool “fire” though promised for New Year 2021, has not yet been released... No existing engineering standards address thermal runaway adequately, or require measures (such as those already used in EV batteries) to pre-empt propagation of runaway events. And BMS's get a few mentions, e.g.: Li-ion batteries are sensitive to mechanical damage and electrical surges, both in over-charging and discharging. Most of this can however be safeguarded by an appropriate Battery Management System (BMS)... -- Cheers, Ralph.