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Earth Radiation Management strategies as alternatives to SRM techniques
Renaud de_RichterInstitut Charles Gerhardt Montpellier
UMR5253 CNRS-UM2 ENSCM-UM1 Ecole Nationale Supérieure de Chimie de Montpellier, 8 rue de l’Ecole Normale
34296 Montpellier Cedex 5, France
CEC14, Climate Engineering Conference 2014, Critical Global Discussions18-21 August, Berlin, Germany. Wednesday August 20th, 2014. Session:
Novel SRM Techniques: Cirrus Clouds Thinning and Marine Sky Brightening
SRM (sunlight reflection methods) SRM aims to reduce incoming Shortwave radiation
Earth Radiation ManagementThe notion of ERM was introduced in 2011 by Mitchell et al, with Modification of Cirrus Clouds to Reduce Global Warming
Mitchell DL, Mishra S, & Lawson RP. Cirrus clouds and climate engineering: new findings on ice nucleation and theoretical basis. Planet Earth, 2011, 257-288.
In (very) short: cirrus clouds trap Longwave radiation below them and contribute to warm the Earth by back radiation; dissipating cirrus clouds would increase outgoing longwave radiation, thus global warming is reduced.
Same thing for CO2: if we reduce it’s concentration we allow more heat energy (IR radiation) to escape out to the space.
=> Thus, for Mitchell et al, CDR belongs, together with Cirrus Clouds reduction, to ERM techniques which target to increase outgoing Longwave radiation
CDR
dissipating Cirrus clouds=> reducing
back radiation
For Mitchell et al, CDR belongs, together with Cirrus Clouds reduction, to ERM techniques which goal is to increase outgoing Longwave radiation
ERM aims to increase outgoing LW
SRM aims to reduce incoming SW
cloud whitening aerosols
Lagrange L1 reflectorsorbital mirrors
sea reflectivity land albedo
LandOceansurface
radiation
GHGR
+ Night Sky radiative cooling
By which mean can we enhance outgoing Earth LW radiation?
Let us start with thermals
Thermals: birds and sailplaners (gliders) know them well
one possibility for generation of thermals
urban heat islandalbedo change
Aufwindkraftwerk described in 1931 by German author Hanns Günther. The prototype was built under the
direction of a German engineer, Jörg Schlaich in Manzanares, Ciudad Real,
150 km south of Madrid Spain. The project was funded by the German
government and the power plant operated for 7 years.
Greenhouse effect+ Stack effect
Cost-competitive energy
if height > 700mArchitects say >1500m
height no problem!
A prototype with 200m high chimney built and fully tested 1982-1989
Updrafts generated by solar chimneys
the hot air is transferred from the surface and released much
higher, where it still rises high in the
troposphere where some of the heat can escape out to
the space
Something else on which we can act to increase OLWR?
CO2
CDR
Figure from NASA
DAC: CO2 direct capture in the Atmosphere• Adsorption on solids (similar to current methods being tested
for Carbon Capture & Sequestration)• Adsorption into alkaline solutions (or alkaline solid resins)• Resulting material must be transported and sequestered• Costs could be competitive since plants can be located near
the sequestration location…• The energy required
to capture 4 CO2 emits 1 CO2 (if done using FFPP)
All methods require energy to move air through the adsorption system EXCEPTED ONE!
http://www.sciencedirect.com/science/article/pii/S1364032112005680
In 2013 we proposed to use artificial trees from Lackner, with
his alkali solid resin, in synergy with a Solar
Updraft ChimneyDAC +25% efficiency using renewable energy
no more fans (investment savings & more energy savings) + other synergies
(resin regeneration…)
Do we forget something on which we can act to increase OLWR?
other GHGs
GHGR
Figure from NASA
Carbon dioxide removal (CDR) techniques aim to remove CO2, a major greenhouse gas, from the atmosphere, allowing more outgoing long-wave to escape (less back radiation).
… photocatalysis may be applied successfully to eliminate or transform all major long-lived well mixed GHGs, but also
soot, tropospheric ozone and other short-lived climate forcers.
by photocatalysis!All other GHGs, can also be removed from the atmosphere…
http://www.sciencedirect.com/science/article/pii/S1389556711000281
But such approaches are still in development
Next way of enhancing outgoing heat radiation
Latent heat
release
A solar chimney variant at the equator
Outside air temperature 35°C, 85% relative humidity. Sea water at 30°C is warmed to 85°C by the sun in black tubing and sprayed at the chimney entrance so has to obtain hot air 60°C / 95% RH The excess water is directed to a saline (salt deposit).
At some height inside the tower, an efficient heat exchanger with the outside air temperature cools the air => clear water condensates (20-30%, useful byproduct?) and the heat of condensation releases heat, warming the air above, making the air lighter… This warmed air in the tower rises and sucks the air column below by increased buoyancy. After the exit out of the tower, the warm and humid air still rises until the condensation releases more latent heat that escapes to the outer space.
Africa
Arabic peninsula
Red Sea averagesurface temperature
in August >30°C
Equatorial Solar chimney (Denis Bonnelle) with piece of cake collector
(initial Drawing: Janning Petersen)
Salt depositsea water is pumped, warmed and spayed
Next way of enhancing outgoing heat radiation
Latent heat
release
tornadoes
atmospheric vortex engine concept from Louis Michaud
(figure by Charles Floyd)
Hurricane Heat Engine close of a Carnot cycle
(image from Emmanuel)
http://vortexengine.caImage from Aqua CERES
Artificial
Are there other methods to help thermal infrared radiation to escape more easily to
the outer space?
YES ! There are many devices able to enhance atmospheric convection
Anymore things to enhance thermal IR out to space?
Figure from NASA
Heat Pipes or Thermosyphons
Half million thermosyphons
are already used
to prevent permafrost
melting
0IL
Half million heat pipes are used to prevent permafrost melting
along roads, railways, oil pipelines… in Siberia, Tibet, Alaska…
Are there credible proposals against the vicious cycle due to loss of polar reflectivity (albedo)?
A melting glacier surface cannot raise its temperature and thus not increase outgoing longwave radiation; any surplus of radiation is thus used for additional meltingOerlemans, J. A projection of future sea level. Climatic change, 1989, 15(1-2), 151-174.
D. Bonnelle has proposed a device transferring sea water in altitude where chilling air makes ice, which is returned to the ocean.
The latent heat of freezing warms the air inside a tall tower anddrives turbines to produce renewable electricity.
The hot air coming out of the chimney enhances atmospheric convection… and the humidity released will produce high albedo fresh
snowhttp://data.solar-tower.org.uk/thesis/2004-Denis-BONNELLE_Solar-chimneys_Energy-towers_etc.pdf
Both a SRM technique by ALBEDO effect and a ERM method by heat transfer from the ocean to the atmosphere
D. Bonnelle also proposed a giant closed heat pipe thermosyphon (book ISBN: 978-2729854072)
top ofa hill
Proposal by: S. Zhou, P.C. Flynn; Geoengineering downwelling ocean currents: a cost assessment.
Clim Change 2005, 71(1-2), 203–220
Both a SRM: by ALBEDO effect and ERM: by heat transfer from the ocean to the atmosphere
SNOW CANONS
Other ways of enhancing outgoing IR radiation?
Emitted by surface and preferably by the atmospheric window
by the atmospheric window8-13 µm
Complementarity between cool roofs…reflective coatings on top of buildings => .SRM
…and night sky radiative coolingradiant materials on top of buildings => ERM
University of Central FloridaParker, D. S., Sherwin, J. R., Hermelink, A. H., & Center, F. S. E. (2008). NightCool: A Nocturnal Radiation Cooling Concept. 2008 ACEEE Summer Study on Energy Efficiency in Buildings, 209-222.
Improved by cold water storage tank
=> reduces even more the cooling costs
Remark: SRM is only possible 12 h/day… SRM
or on one half of the planet at the same time
Outgoing longwave radiation, March 18, 2011 from Aqua CERES data
…meanwhile outgoing Longwave radiation is permanent
Some recentprogress done by researchers in Stanford and Harvard universities
Geoengineering SRM diverts sunlight radiation back into space by increasing albedo, increasing short wave radiation reflection (parasol effect): thus less light reaches the Earth surface.
But blocking the sun will not help the humans to stop spewing billions of tons of CO2 into the atmosphere
ERM consists to increase longwave outgoing radiation, by the use of atmospheric convection devices, which are a full set of unusual renewable energies, which allow more heat to leave the Earth surface and at the same time cool the Planet, provide humans with all their energy needs and progressively de-carbonize the energy sector
Pros and Cons of SRM and ERMSRM ERM
FAQ• Q1: isn’t it like science fiction?
Science fiction??? what about orbital mirrors?and reflector arrays at the Lagrange (L1) point? and millions of artificial trees? …and… and …
• Q2: if so perfect and so good, … why aren’t they already built and in operation?
Behind “atmospheric convection devices”, the science is strong and they are proven technologies!They are worth being studied to help cool the Earth by ERM
Answer later, after the talk…
• Q3: are there complementarities between: SRMERM & ?Yes! Some examples, after the talk…
More information on
Open Access: http://www.sciencedirect.com/science/article/pii/S1364032113008460
Thank you for your attention
QUESTIONS?
Additionnal slides
SRM Advantages: It can be cheap Rapid deployment is possible It allows to “buy time” It is often presented as a “last resort”, in case
of climate emergency
SRM Drawbacks: Imperfectly compensates for CO2 driven warming Doesn’t stop ocean acidification, nor CO2 emissions May introduce new environmental risks like affecting
precipitation patterns and volumes... Treats the symptoms rather than cure the illness
Comments on SRM
Solar updraft tower and downdraft energy tower are under industrial development in the US (Texas & Arizona)
Atmospheric vortex engine found funding for the next prototypes in Canada. The development plan is going on.
Heat pipes are widely used in several industrial sectors and prevent permafrost melting on the Trans Alaska Pipeline and the Qinghai-Tibet Railway.
Radiative cooling technologies and new materials are available for heat transfer by the atmospheric window during clear sky nights.
Future ERM prospects
How can we cool the Earth surface?
Some examples of convection towers and devices:• http://en.wikipedia.org/wiki/Energy_tower_(downdraft)
http://www.solarwindenergytower.com/the-tower.html• http://en.wikipedia.org/wiki/Solar_updraft_tower
http://www.solar-updraft-tower.com/en#commercial_sut/index http://www.theengineer.co.uk/energy-and-environment/news/per-lindstrand-
plans-1km-high-inflatable-solar-energy-chimney/1017508.article• http://en.wikipedia.org/wiki/Vortex_engine http://www.fmrl.gatech.edu/drupal/projects/solarvortex Georgia Institute of Technology
http://phys.org/news/2012-12-entrepreneur-funding-tornado-power.html• http://en.wikipedia.org/wiki/Radiative_cooling Harvard University, Cambridge
http://www.pnas.org/content/early/2014/02/26/1402036111.short • http://en.wikipedia.org/wiki/Heat_pipe
There exist many convection devices are able to break the GHGs insulating envelope surrounding the Earth and create thermal bridging, thus increase outgoing longwave radiation
Conclusion: by progressively replacing fossil fuel power plants, these unusual renewable energies will produce electricity with no CO2 emissions and thus will reduce global warming, cool the Planet, stop sea level rise, stop ocean acidification…