The carbon dioxide removal potential of Liquid Air Energy Storage: A high-level technical and economic appraisal

Liquid Air Energy Storage(LAES)is at pilot scale.Air cooling and liquefaction stores energy;reheating revaporises the air at pressure,powering a turbine or engine(Ameel et al.,2013).Liquefaction requires water&CO2 removal,preventing ice fouling.This paper proposes subsequent geological storage of this CO2–offering a novel Carbon Dioxide Removal(CDR)by-product,for the energy storage industry.It additionally assesses the scale constraint and economic opportunity offered by implementing this CDR approach.Similarly,established Compressed Air Energy Storage(CAES)uses air compression and subsequent expansion.CAES could also add CO2 scrubbing and subsequent storage,at extra cost.CAES stores fewer joules per kilogram of air than LAES–potentially scrubbing more CO2 per joule stored.Operational LAES/CAES technologies cannot offer full-scale CDR this century(Stocker et al.,2014),yet they could offer around 4%of projected CO2 disposals for LAES and<25%for current-technology CAES.LAES CDR could reach trillion-dollar scale this century(20 billion USD/year,to first order).A larger,less certain commercial CDR opportunity exists for modified conventional CAES,due to additional equipment requirements.CDR may be commercially critical for LAES/CAES usage growth,and the necessary infrastructure may influence plant scaling and placement.A suggested design for low-pressure CAES theoretically offers global-scale CDR potential within a century(ignoring siting constraints)–but this must be costed against competing CDR and energy storage technologies.

Glacier geoengineering to address sea-level rise:A geotechnical approach

It is remarkable that the high-end sea level rise threat over the next few hundred years comes almost entirely from only a handful of ice streams and large glaciers.These occupy a few percent of ice sheets’coastline.Accordingly,spatially limited interventions at source may provide globally-equitable mitigation from rising seas.Ice streams control draining of ice sheets;glacier retreat or acceleration serves to greatly increase potential sea level rise.While various climatic geoengineering approaches have been considered,serious consideration of geotechnical approaches has been limited e particularly regarding glaciers.This study summarises novel and extant geotechnical techniques for glacier restraint,identifying candidates for further research.These include draining or freezing the bed;altering surface albedo;creating obstacles:retaining snow;stiffening shear margins with ice;blocking warm sea water entry;thickening ice shelves(increasing buttressing,and strengthening fractured shelves against disintegration);as well as using regional climate engineering or local cloud seeding to cool the glacier or add snow.Not all of these ideas are judged reasonable or feasible,and even fewer are likely to be found to be advisable after further consideration.By describing and evaluating the potential and risks of a large menu of responses e even apparently hopeless ones e we can increase the chances of finding one that works in times of need.

Geoengineering and the blockchain: Coordinating Carbon Dioxide Removal and Solar Radiation Management to tackle future emissions

Geoengineering is a proposed response to anthropogenic global warming (AGW). Conventionally it consists of two strands: Solar Radiation Management (SRM), which is fast-acting, incomplete but inexpensive, and Carbon Dioxide Removal (CDR), which is slower acting, more expensive, and comprehensive. Pairing SRM and CDR offers a contractually complete solution for future emissions if effectively-scaled and coordinated. SRM offsets warming, while CDR takes effect. We suggest coordination using a blockchain, i.e. smart contracts and a distributed ledger. Specifically, we integrate CDR futures with time and volume-matched SRM orders, to address emissions contractually before release. This provides an economically and environmentally proportionate solution to CO2 emissions at the wellhead, with robust contractual transparency, and minimal overhead cost. Our proposal offers a 'polluter pays' implementation of Long & Shepherds SRM 'bridge' concept. This 'polluter geoengineers' approach mandates and verifies emissionslinked payments with minimal friction, delay, or cost. Finally, we compare alternative market designs against this proposal, finding that this proposal offers several advantages. We conclude that blockchain implementation of the 'polluter geoengineers' approach is attractive and feasible for larger wellhead contracts. We also identify a handful of advantages and disadvantages that merit further study.

Security of solar radiation management geoengineering

Solar Radiation Management (SRM) geoengineering is a proposed response to anthropogenic global warming (AGW)(National Academy of Sciences, 2015). There may be profound - even violent - disagreement on preferred temperature. SRM disruption risks dangerous temperature rise (termination shock). Concentrating on aircraft-delivered Stratospheric Aerosol Injection (SAI), we appraise threats to SRM and defense methodologies. Civil protest and minor cyberattacks are almost inevitable but are manageable (unless state-sponsored). Overt military attacks are more disruptive, but unlikely - although superpowers' symbolic overt attacks may deter SRM. Unattributable attacks are likely, and mandate use of widely-available weapons. Risks from unsophisticated weapons are therefore higher. An extended supply chain is more vulnerable than a secure airbase - necessitating supply-chain hardening. Recommendations to improve SRM resilience include heterogeneous operations from diverse, secure, well-stocked bases (possibly ocean islands or aircraft carriers);and avoidance of single-point-of failure risks (e.g. balloons). A distributed, civilianoperated system offers an alternative strategy. A multilateral, consensual SRM approach reduces likely attack triggers.

Distributed governance of Solar Radiation Management geoengineering:A possible solution to SRM’s“free-driver”problem?

Geoengineering(deliberate climate modification)is a possible way to limit Anthropogenic Global Warming(AGW)(Shepherd,2009;National Research Council,2015).Solar Radiation Management geoengineering(SRM)offers relatively inexpensive,rapid temperature control.However,this low cost leads to a risk of controversial unilateral intervention—the“free-driver”problem(Weitzman,2015).Consequently,this creates a risk of counter-geoengineering(deliberate warming)(Parker et al.,2018),resulting in governance challenges(Svoboda,2017)akin to an arms race.Free-driver deployment scenarios previously considered include the rogue state,Greenfinger(Bodansky,2013),or power blocs(Ricke et al.,2013),implying disagreement and conflict.We propose a novel distributed governance model of consensually-constrained unilateralism:Countries’authority is limited to each state’s fraction of the maximum realistic intervention(e.g.,pre-industrial temperature).We suggest a division of authority based on historical emissions(Rocha et al.,2015)—noting alternatives(e.g.,population).To aid understanding,we offer an analogue:An over-heated train carriage,with passenger-controlled windows.We subsequently discuss the likely complexities,notably Coasian side-payments.Finally,we suggest further research:Algebraic,bot and human modeling;and observational studies.