Showing posts with label CDR. Show all posts
Showing posts with label CDR. Show all posts

Tuesday, January 14, 2014

Six commercially-viable ways to remove CO2 from the atmosphere and/or reduce CO2 emissions


by Roelof D Schuiling and Poppe L de Boer


Background

Almost all of the CO2 that has ever leaked out of the planet has been removed from the atmosphere and the ocean, and sustainably stored in rocks, mainly by weathering, and also in the later part of the Earth’s history by storage as organic carbon. During weathering, which is the reaction of rocks with CO2 and water, CO2 is first converted to bicarbonate solutions. In the ocean corals, shellfish, and plankton convert them to carbonate sediments, which form the ultimate sustainable storage of CO2 (Figure 1).

Figure 1. A Karst landscape in China is one of the many stores for CO2 of the world.

Six solutions

Six low-cost or financially self-supporting ways are described in which we can store large
volumes of CO2 and/or significantly diminish CO2 emissions:

  1. Nickel Farming: A switch from nickel mining, ore dressing, and nickel recovery to nickel farming by the use of nickel hyperaccumulator plants. This switch will cut down CO2 emissions because it avoids the energy-intensive steps in the nickel cycle and enhances the weathering of olivine or serpentine which captures additional CO2.
  2. Biodiesel from Diatoms: Diatoms contain approximately 50% of lipids, which makes them an ideal starting material for the production of biodiesel. They grow fast, provided they have a source of silica. They do not suffer from drawbacks of land-grown biofuel crops. They do not occupy vast tracts of land that are urgently needed for food production, and they do not require vast amounts of scarce irrigation water and fertilizer. The use of biodiesel from diatoms will reduce the CO2 emissions from fossil fuels.
  3. Quenching Forest Fires: Forest fires are the second largest emitter of CO2, after fossil fuels. It was demonstrated that quenching such fires with a slurry of serpentine powder is considerably more effective than quenching with water. This reduces the emissions of CO2 by the fires and the associated financial losses. The serpentine that was calcined by the fire reacts very fast with CO2 and water afterwards, thereby compensating part of the emitted CO2 during the fire. A better and quicker mastery over forest fires may also help to save lives.
  4. Supergreen Energy: If the heat that is released by the weathering of olivine is trapped, this would represent a huge alternative source of energy that additionally captures large volumes of CO2, hence the name supergreen energy. A basic scenario is described how this could be achieved.
  5. Coastal Protection: When olivine is used for coastal protection (breakwaters, artificial reefs, sand replenishment on beaches) this has a direct effect against ocean acidification. CO2 is absorbed as bicarbonate, and the pH of the surrounding waters rises.
  6. Olivine in High-Energy Marine Environments: Large areas of shallow seas are subjected to strong currents that can transport gravel. When olivine grit is spread on the sea floor, the grains are kept in motion and bump and rub against each other. This destroys reaction-limiting silica coatings on the grain surfaces and releases micronsized slivers that rapidly react with sea water. It is the most direct way to counter ocean acidification.

1. Nickel Farming

All mining operations have an impact on the environment. This also holds for nickel, independent of the type of ore, whether nickel laterite or nickel sulfide. Nickel laterites must be leached and nickel sulfides must be roasted and dissolved. These steps are energyintensive and polluting. These disadvantages can be reduced if part of the world nickel production is gradually replaced by a switch to nickel farming. A fairly large number of plant species from different families are known to exhibit the remarkable property that they very effectively extract nickel from nickel-rich soils and store it in their tissues (Figure 2). Soils on serpentinized peridotites often contain no more than 0.2% of nickel, but the ash of these plants may contain 10% or more of nickel, much richer than the richest nickel ores. If some NPK fertilizer is spread over nickel-rich soils and such plants are sown, these nickel hyperaccumulator plants can be harvested at the end of the growing season, and their nickel content can be recovered after ashing. Several of these plants are perennial, so they do not need to be sown every year.

Figure 2. Alyssum corsicum, a nickel hyperaccumulator.

A first estimate [1] shows that the recovery of nickel by using these plants will cost no more than the current way of nickel production. This means that all the savings on CO2 expenditure and CO2 storage are essentially cost-free. In instances where an appropriate value may be associated with the CO2 savings compared to conventional nickel production, nickel farming may economically outcompete incumbent nickel production processes.

Once such nickel hyperaccumulation systems will have been fully developed and become deployable, it is hoped that governments adopt incentive structures that oblige mining companies with nickel mining assets to conduct at least part of their businesses with these methods and that associated CO2 savings and removals are quantified and verified. In addition, because the nickel obtained from phytomining is not extracted from nickel ores but from common peridotite rocks, nickel farming will extend the lifetime of nickel ore deposits.

2. Biodiesel from Diatoms

Diatoms (siliceous algae) make up a large part of the biomass in the oceans. They consist about 50% of the lipids, which makes them an ideal raw material for the production of biodiesel. The process to make biodiesel from algae is already known. They grow fast and can outcompete their competitors in the algal world in the fight for food, provided that there is sufficient silica available in their environment. Diatoms need silica for the construction of their silica skeleton (Figure 3). An extensive discussion of the role of dissolved silica in promoting the growth of diatoms at the cost of other plankton like dinoflagellates can be found in [2].

Figure 3. Diatoms have delicate silica skeletons.
Land-grown biofuels (among others oil palm, sugarcane, sweet sorghum, soybean, maize) occupy vast tracts of land that would normally be used for food production, or land that used to be the territory of threatened species like the orangutan. They also need vast volumes of scarce irrigation water and fertilizer. This results in higher prices for these fertilizers, which will push up their price as well as the price of food.

Diatoms do not have these drawbacks, but before they can be used as an alternative source of biofuel, the problems of mass culturing and harvesting them must be solved. A large-scale mariculture of diatoms might take the following shape. An artificial lagoon can be sectioned off by a dike around a sector of shallow seawater in front of a beach section.

The beach between the low-tide mark and the high-tide mark must be covered by a layer of olivine sand with a thickness of about 0.5 m. One or more U-shaped tubes are left in the dike that connects the lagoon with the open sea, permitting the tide to reach the lagoon and to alternatively wet and drain the olivine beach. These tubes should be closed by a perforated metal plate covered with a plankton net. This would permit the exchange of water, but prevent the diatoms to be carried out of the lagoon by the ebb. The olivine will weather, and the weathering solution, including the silica that is set free during the olivine reaction, will be distributed in the lagoon. In addition, the bicarbonate that is captured during olivine weathering will be used by the diatoms for photosynthesis.

When the silica limitation is removed, diatoms will form a quasi-monoculture in the lagoon. Nutrients should, of course, be added, mainly for their ammonia and phosphate requirements. A cheap way to do this would be by the use of struvite, an ammonium-magnesium phosphate that is produced by a simple and robust technology in the treatment of organic wastes, including manure, urban waste, and urine [3]. Struvite is a slow-release fertilizer that will steadily add ammonium and phosphate to the lagoon. The addition of nutrients should be limited, however, because diatoms react to a slight starvation by raising their lipid content, which increases their value for biodiesel production. The diatom production can be increased by underwater lighting at night.

Harvesting the diatoms efficiently is a major problem. The following possibility may provide a solution. Dig a hole inside the lagoon. Dead diatoms will collect in this pit, also thanks to the fact that they are relatively heavy due to their silica skeletons. From time to time, this mass of dead diatoms can be sucked up, drained and transported to the biofuel plant.

When the culture and harvesting of vast volumes of diatoms can be successfully accomplished, this application will become financially self-supporting and will reduce CO2 emissions from the burning of fossil fuels. It can be setup in any country with marine coastlines, preferentially in dry climate zones with abundant sunshine.

3. Quenching Forest Fires

Forest fires (Figure 4) are the largest CO2 emitters after the burning of fossil fuels. Forest fires and, to a lesser extent, other forest losses account annually for about 6 Gt of extra CO2 emissions on a total of somewhat more than 30 Gt of human CO2 emission [4]. They cause every year not only huge financial losses but also the deplorable loss of human lives. Experimental fires at the test site of Brandbeveiliging BV (Fire Protection) in the Netherlands were considerably faster and completely extinguished by spraying with a suspension of serpentine powder than with plain water. Serpentinite powder from the PASEK mine in North-West Spain and from the Isomag Mine in Austria was used with equally positive results.

Figure 4. Forest fires are the second largest emitter of CO2 in the world.
Serpentine can be considered the hydrated equivalent of olivine. Huge massifs of serpentinite are formed by the interaction of olivine with hydrothermal waters and also on the ocean floor along mid-ocean ridges. Serpentinite is a soft rock and serpentine is similar to a clay mineral. Like any other clay, it can be baked into a hard, brick-like substance. When this calcined serpentine is pulverized, it turns out that the powder reacts fast with CO2 and water, considerably faster even than olivine. It would be an excellent material to rapidly remove CO2 from the atmosphere, but baking it costs a lot of energy and associated CO2 emission. So, it is a pity, but using calcined serpentine against climate change is out…, except in cases where one wants to quickly remove as much heat as possible, like in extinguishing forest fires. When serpentine slurries were tested in test fires, they not only removed a considerable amount of heat from the fire, but they displayed another property which is probably more decisive. The serpentine that was sprayed over the fire turned into a thin baked impermeable skin that prevented the access of oxygen to the burning material, and also prevented the emission of the inflammable gases from the burning wood.

So, when forest fires are raging, the spraying of serpentine slurries (almost as simple as spraying water, because a 40% serpentine slurry is still very fluid) can reduce the extent and severity of such fires. When a reduction of 10% in forest losses could be achieved worldwide, this would already be a major breakthrough, since this represents a reduction of 0.6 Gt of CO2 emissions each year.

Moreover, after extinction of the fire, the calcined serpentine will quickly react with CO2 and the first rainwater, thereby compensating part of the CO2 that was emitted by the fire. It is clear that the spraying of serpentine (serpentine powder is a cheap and ubiquitous material) is a very cost-effective way of reducing the huge financial losses from forest fires, and it holds the promise of reducing losses of life as well. It pays amply for the reduction in CO2 emission by limiting the areal extent of burnt forest and by the capture of CO2 by the reaction of the calcined serpentine afterwards. It also limits the required volumes of water considerably, which is important in hot dry summers in countries that are most vulnerable for forest fires and have only limited fresh water resources.

It should be considered whether the spraying of serpentine slurries can also be used in the containment of tunnel fires.

4. Supergreen Energy

A property of olivine weathering that is commonly overlooked is its energy production. When olivine is weathering under conditions of limited water flow, it weathers according to:

Mg2SiO4 + CO2 + H2O    Mg3Si2O5(OH)4 + MgCO3
Olivine, Carbon dioxide, Water             Serpentine,   Magnesite   

Serpentine is like a clay mineral, and magnesite is similar to limestone. It is well known that baking clays to make bricks costs a lot of energy and the same holds for burning lime to make quicklime. If we follow the reverse route and make clays and carbonates, such energy is set free. Unfortunately, weathering reactions are notoriously slow, so there are no technological applications for this energy yet, because under normal conditions this heat will be radiated or conducted away. That is a pity, because the energy that is produced by the weathering of olivine is considerable. The heat flow anomalies along the mid-ocean ridges may be due, for a large part, to the widespread serpentinization of mantle rocks when they react with infiltrating sea water [5].

In a system that is very well isolated and has a large volume-to-surface ratio, it might be possible to recover most of that energy. Rocks are excellent thermal isolators, as shown by caves. If one visits a cave in summer, it feels nice and cool, and in winter it feels pleasantly warm. This is because the surrounding rocks provide a good thermal isolation and keep the cave at a fairly constant temperature throughout the year. The larger the volume of olivine sand under good isolating conditions, the better it will be able to develop and keep a high temperature. One might say, volume stands for heat production and surface area stands for heat loss; thus, the larger the volume (and the thicker the isolation), the lesser the heat loss.

A scenario that provides these conditions could be the following. An existing 550-m deep lignite mine in Germany (Figure 5) will be taken as an example; but in fact, any deep open pit mine could serve, whether in operation or left as a scar in the landscape after closure .

Figure 5. A lignite mine in Germany.
The lignite mining goes on at the front end of the mine, while the mined-out rear part is filled with the overburden that was first removed to reach the lignite seams. This way the mine moves slowly through the landscape. Villages are torn down in front of the mine and rebuilt at the backside. Instead of refilling the whole mine with the overburden, the lower 250 m may be filled with olivine sand and then topped off with the remainder of the overburden. This setup provides thermal isolation and also sufficient counter-pressure to maintain the pore waters in a liquid state. Before doing this, a network of perforated pipes and heat exchangers should be installed in the olivine sand, through which water (or steam) and CO2 can be injected. A set of thermistors inside the olivine mass will make it possible to follow its thermal evolution.

As long as the temperature is low, the reaction will be slow. In order to kickstart the process, it is advisable to first inject steam to heat the inside of the mass. This will increase the reaction rate, and as the reaction takes off, the temperature will rise further and the reaction accelerates.

When the system has reached a sufficiently high temperature to be of interest for power production, water is passed through the heat exchangers and converted to high-pressure steam.

It should be evident that such a system will require a lot of additional and rather unusual engineering before it can be operational. On the other hand, the potential reward is huge because it represents an almost unlimited amount of energy. This energy is called supergreen energy because it does not produce CO2, but, on the contrary, it traps it in a safe and solid form. The question asked by the author in [6] is relevant ‘So what would we prefer, a CCS infrastructure that uses a quarter of a power station’s electricity to sequester its CO2 emissions under the North Sea or one that generates additional electricity and useful materials products?’.

A major technical problem may arise if silica that is released during the olivine reaction would form a layer on the olivine grains, preventing the reaction to proceed. A possible way out is to mix the olivine sand with some minute quartz grains. Quartz has a much lower solubility than amorphous silica, so the dissolved silica that is released in solution will tend to diffuse to the quartz grains and precipitate as an overgrowth on quartz surfaces instead of on the olivine grains, leaving the olivine surfaces free for continued reaction.

5. Coastal Protection

Olivine can be used in several ways to protect coastlines against erosion. Olivine is considerably heavier than normal quartz sand (specific masses of 3.4 versus 2.65 kg/m3), which makes it more resistant to physical erosion. Olivine blocks can be used in the construction of permeable breakwaters. In a permeable triangular breakwater, pointing into the sea, the force of the longshore (flood and ebb) currents is weakened because part of the water passes through the breakwater and loses momentum in doing so, while another part is deviated from the coast. Both effects reduce coastal erosion. If the sections at either side of the breakwater are covered with olivine sand, it will resist erosion even better.

Another way of using olivine for coastal protection is the construction of olivine reefs at strategic points to keep waves and currents away from the coast. If the seawater that is enclosed in the reefs is only slowly refreshed, its pH will rise as a consequence of the olivine reaction. This may lead to the precipitation of calcite, so that these reefs are self-cementing. They will become hatching and hiding places for fish and a place for mussels and oysters to settle (Figure 6).

Figure 6. The sea as a threat: the Hondsbossche Zeewering along the Dutch Coast.
Stretches of beach that lose sand can be restored by spreading olivine sand on the beaches. Olivine sand on beaches feels well, and children love to build their sand castles with it and make sand sculptures of dolphins and seals (Figure 7).

Figure 7. The sea as an ally. Children making sand sculptures of olivine sand that
will merge with the sea at high tide and help in counteracting ocean acidification.
Very rough coastal stretches can be covered with olivine grit, preferably of various sizes. In imitated surf experiments, we have shown that mixtures of different grain sizes become rounded and are abraded faster than single grain sizes by the multiple grain-to-grain collisions [7]. During this polishing in the surf, small micron-sized slivers of olivine are knocked off (see also Section ‘Olivine in high-energy marine environments’). These slivers react very rapidly with sea water and add alkalinity to counteract ocean acidification. It was even found that brucite (Mg(OH)2) formed already after a few days in experiments with olivine and seawater. From the observations on white smokers [8], it is known that brucite is rapidly transformed into aragonite (Figure 8).

Figure 8. Sixty-meter tall aragonite (replacing brucite) chimneys on Lost City seamount.
Coastal protection with olivine, instead of with the usual basalt blocks, will add alkalinity to the ocean and also provide places of interest to tourists. This makes this combined function of CO2 capture and alkalinity provider also financially attractive. Rough stretches of beach covered with olivine grit can serve as natural tumbling devices, where nicely rounded green grit can be produced by the surf. These may serve for applications as diverse as chicken grit and covering material for driveways. Tourists may also find these polished marbles attractive collector’s items. Using the surf which is free of charge, instead of mechanical crushing and tumbling devices, is an additional modest saving. Another financial advantage is that olivine cargo ships can unload their olivine directly in front of the coast, thus avoiding harbor dues.

6. Olivine in High-Energy Marine Environments

It is a paradigm that weathering on land, and under marine conditions, always would be a slow process. When olivine grains, preferably of different sizes, are free to be kept in motion by currents, their weathering is a fast process. The grains are quickly rounded and abraded by mutual collisions (Figure 9), producing myriads of micron-sized slivers (see picture in Additional file 1; see also [9]).

Figure 9. Angular olivine grains are quickly rounded
and abraded by mutual collisions when kept in motion.
In experiments where modest current action was imitated by letting olivine grains rotate slowly along the bottom of an Erlenmeyer, the water had become opaque white after a few days of rotation, the pH of the solution had gone up, and neoformed grains of brucite, a mineral known to transform into carbonate fast, had evolved.

Many shallow sea floors are covered with gravel. When 700,000 km2 of such sea bottoms are covered each year with a 1-cm thick layer of olivine grit, this would compensate the entire anthropogenic CO2 emissions, and raise the pH of the oceans. To make it more concrete, the following example may serve. Part of the continental shelf between the Shetland Isles and France, i.e. the Southern Bight of the North Sea, the English Channel and the Irish Sea, is covered with sand waves, and in and around the Channel, an area of well over 100,000 km2 experiences bed stresses capable of transporting gravel [10,11]. If a volume of 0.35 km3 coarse olivine is spread over 35,000 km2 of this area, this would compensate 5% of the world’s CO2 emissions, that is more than the combined emissions of the adjoining countries, the UK, France, Ireland, Belgium and the Netherlands together [9].

Another site where the spreading of coarse olivine grit may work out well is the Maelstrom, with very strong tidal current in the Lofoten Islands, Norway, and there are many more suitable areas in shallow shelf seas.

The alkalinity brought in by the olivine is of great importance. It counteracts ocean acidification, and the contained bio-limiting nutrients, Si and Fe, enhance marine productivity thereby capturing additional CO2. Another factor that makes this approach low-cost is that large carriers can bring the olivine directly to the place of use, where they are discharged, thus avoiding harbor dues and additional transport costs.

Results and discussion

A preliminary volume and cost-benefit estimate

At this early stage, it is virtually impossible to provide accurate estimates of the volumes of CO2 involved for each of the options, and of the amount of money potentially won or lost.

Table 1 should, therefore, be taken as a not too-educated guess of the orders of magnitude involved in each of the six options. The large spread in the numbers for the first five options is caused by the uncertainty whether the particular activity will be executed in a few tests on essentially pilot scale, or as a worldwide activity.

Table 1. Estimated order of magnitude of CO2 capture and/or emission reduction and money involved
CO2 capture or emission reduction Cost or benefit  
Unit1 Million ton1 Million euro
Options:
1. Nickel farming1 to 500 to +200
2. Biodiesel from diatoms50 to 1,000+10 to +500
3. Quenching forest fires100 to 1,000+200 to + 2,000
4. Supergreen energy20 to 1,000+50 to + 5,000
5. Coastal protection10 to 1,000−1 to + 100
6. Olivine in high-energy waters 25,000−500,0003
3If the figure of 50 billion euro of costs for the option in the last row is compared to the cost of the CCS-option, the deficit changes into a benefit of 0 billion euro [cf. 12].

The cost of the olivine in high-energy shallow seas is calculated as the total costs of spreading 25 Gt of crushed olivine in shallow high-energy seas. When compared to carbon capture and storage (CCS), it should not be marked as a cost of 50 billion euro, but as a benefit of 0 billion euro.

Conclusions

It is likely that the first five examples of large-scale applications of the olivine option that are presented in this paper will all turn out to be profitable or, at least, financially self-supporting without requiring subsidies or carbon credits. The costs/benefits of the spreading of olivine in high-energy shallow seas depend on the way to calculate it. If it is just the cost of the operation itself, this total solution of the climate problem and ocean acidification costs a lot of money (order of 15% of the price of the equivalent amount of crude oil), but if it is compared to the costs of the CCS alternative, which is still on the agenda of several governments, it will save a huge amount of money. The major obstacle may well be that the unusual character of the proposals will delay their introduction because parties have a tendency to shy away from untested innovative approaches. Each of the six represents a major breakthrough in the attempts to control climate change and ocean acidification.

Methods

This study utilized stimulation of a chemical reaction that has been common at the Earth’s surface over the last 4.5 billion years.

Competing interests

The authors declare that they have no competing interests.

Authors’ contributions

RDS developed ideas about the use of stimulated olivine weathering as a means to counter human CO2 emissions. PDB carried out flume experiments. Both authors contributed to, read and approved the final manuscript.

Acknowledgements

Prof. Elburg (Durban) is thanked for suggesting some significant modifications. David Addison from Virgin Group, London is thanked for going through the text and suggesting a number of clearer formulations.

References
  1. Schuiling RD: Farming nickel from non-ore deposits, combined with CO2 sequestration. Natural Science 2013, 5:4.
  2. Scheffran J, Dürr HH, Wolf-Gladrow DA, De La Rocha CL, Köhler P, Renforth P, Joshua West A, Hartmann J: Enhanced chemical weathering as a geoengineering strategy to reduce atmospheric carbon dioxide, supply nutrients, and mitigate ocean acidification. Rev. Geophysics 2013, 51:113–149.
  3. Schuiling RD, Andrade A: Recovery of struvite from calf manure. Environ. Techn 1999, 20:765–768.
  4. Van der Werf GR, Morton DC, DeFries RC, Olivier JGJ, Kasibhatla PS, Jackson RB, Collatz GJ, Randerson JT: CO2 emissions from forest loss. Nature Geoscience November 2009, 2009:2.
  5. Schuiling RD: Serpentinization as a possible cause of high heat-flow values in and near oceanic ridges. Nature 1964, 201:807–808. no 4921.
  6. Priestnall M: Making money from mineralization of CO2. Carbon Capture Journal, February 03, 2013.
  7. Schuiling RD, de Boer PL: Rolling stones; fast weathering of olivine in shallow seas for cost-effective CO2 capture and mitigation of global warming and ocean acidification. Earth Syst. Dynam. Discuss 2011, 2:551–568. doi:10.5194/esdd-2-551-2011.
  8. Shipboard Scientific Party, Roe KR, Schrenk MO, Olson EJ, Lilley MD, Butterfield DA, Jeff G, Gretchen F-G, Blackman DK, Karson JA, Kelley DS: An off-axis hydrothermal vent field discovered near the Mid-Atlantic Ridge at 30°N. Nature 2001, 412:145–149.
  9. de Boer PL, Schuiling RD: Fast weathering of olivine in high-energy shallow seas for cost-effective CO2 capture as a cheap alternative for CCS, and effective mitigation of ocean acidification. AGU 2013 Fall Meeting, OS13A-1689. ftp://ftp.geog.uu.nl/pub/posters/2013/Mitigation_of_CO2_emissions_by_stimulated_natural_rock_weathering%e2%80%93fast_weathering_of_olivine_in_high-energy_shallow_seas-Schuiling_deBoer-November2013.pdf
  10. Belderson RH, Wilson RH, Holme NA: Direct observation of longitudinal furrows in gravel, and their transition with sand ribbons of strongly tidal seas. In Tide-Influenced Sedimentary Environments and Facies. Edited by de Boer PL, et al. Dordrecht: Reidel; 1988:79–90.
  11. Mitchell AJ, Ulicny D, Hampson GJ, Allison PA, Gorman GJ, Piggott MD, Wells MR, Pain CC: Modelling tidal current-induced bed shear stress and palaeocirculation in an epicontinental seaway: the Bohemian Cretaceous Basin, Central Europe. Sedimentology 2012, 57:359–388.
  12. McKinsey & Company: Carbon Capture & Storage: Assessing the Economics; Report September 22, 2008.

© 2013 Schuiling and de Boer
This article was published December 21, 2013, at enveurope.com/content/25/1/35 under a Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.




Tuesday, March 5, 2013

An integrated systems plan for 10 year carbon pumpdown to 280ppm

Aaron Franklin
By Aaron Franklin

There's little point getting too distracted with talk on how to reduce human CO2 emissions until we have succeeded in reversing the Arctic sea-ice crash.

However, as geoengineering for this will be an ongoing annual commitment until CO2 is back in the region of 280ppm, we do need a plan to pump carbon out of the atmosphere and the sea (where 60% of the 500 Gton total human contribution is residing.)

Current estimates are 56.4 billion tonnes C/yr (53.8%), for terrestrial primary production, and 48.5 billion tonnes C/yr for oceanic primary production.

It's been learned that the primary ocean production has fallen by nearly half in the last 100 years. The reduction in windblown dust from irrigation and cultivation of arid areas and the prolonging of the growing season of grasses in arid areas by CO2 increases is most likely the biggest cause of this. This has resulted in the amount of natural wind-borne iron-carrying dust falling dramatically, 30% over the past 30 years alone.
  • Tropical rainforests have globally 8 million square km with biomass productivity of 2000g Carbon per square meter for a total of 16 Gtons of Carbon per year. Doubling this area would only get near an extra 16 Gtons of annual carbon pulldown after 1 to 2 decades and with studies showing drought stress already turning Amazon and stheast Asian rainforests now net CO2 producers rather than removers no gains might occur at all.

  • Temperate forests have globally 19 million square km with biomass productivity of 1,250g Carbon per square meter for a total of 24 Gtons of Carbon per year. Doubling this area would only get near an extra 24 Gtons of annual carbon pulldown after 1 to 2 decades, and then would need a further 20 years to remove the 500 Gton existing carbon debt, and thats assuming that 100 percent of carbon taken in by these trees can be kept away from consumers and decomposers.

  • The Oceans have globally 350 million square km with average biomass productivity of 140 gC/m²/yr for a total of 48.5 Gtons of Carbon per year. This is heavily weighted towards coastal areas at present. The open Oceans are 311 million sqkm with average biomass productivity of 125 gC/m²/yr and a total of 39 Gtons of Carbon per year, however, as can be clearly seen on the map below, some 80% of the ocean are so isolated from land sourced nutrient inputs that their productivity is about 1/100 of the most productive oceanic zones.

 map of the earth showing primary (photosynthetic) productivity, from: http://upload.wikimedia.org/wikipedia/commons/4/44/Seawifs_global_biosphere.jpg

Oceanic desolate zone at 80% of 311 million sqkm is 249 million sqkm. 50 GtonsC/249million = 201 tonsC per sqkm per year = 200g C per sqmeter per year average. With prime coastal Aquatic enviroment like estuarys and coral reefs producing 10x that at 2000+ gC/sqm it would seem very achievable to increase the deep ocean productivity this much.

Doubling the productivity of the oceans could pump down the global 500 Gton Carbon burden in as little as 10 years and is possible, affordable, already very well studied.

In the currently near sterile central oceans the absence of an existing foodchain would ensure most of this Phytoplankton Carbon will die and sink a couple of hundred meters into the tidal mixed layer.

This can be a problem....

The amount of organic carbon needed to completely remove all oxygen from the WHOLE ocean as it is decomposed by bacteria is thought to be 1000 Gton C. Just letting the phytoplankton sink into the tidal mixed zone, which is low in oxygen already, would be a very bad idea. Back to this later.

As can be seen on the front page graphic of: http://www.aslo.org/meetings/Phytoplankton_Production_Symposium_Report.pdf
The benefits of iron fertilization alone are only achievable in the Nutrient Rich Iron Depleted zones of the southern ocean to 35degr sth, the equatorial oceans to 20degr sth and 10degr nth, and the nth pacific from 40 degr nth. These areas can easily be stimulated urgently.

At the low figure of 1 million tonC/1ton Fe we would annualy need 50GtC/1MtC= 50000 tons of iron dust -bugger all.

Antarctic krill have a total fresh biomass of up to 500 million tons. This will increase several times over when we iron fert the southern ocean.

The rest of the desolate zones need nitrogen and phosphorus. Rather than using mined phosphates and CO2 producing urea for nitrogen there are these alternatives:

  • Natural volcanic ash. There are concerns about heavy metal contamination from this but as long as we stick to siliceous ash from recycled seafloor volcanism we should be pretty OK.
  • Wave pumped chimneys. Tested already, these pump nutrient rich deep benthic water via wave power. We would however need millions of these due to scale limitations imposed by ocean wavelengths.
  • Chimneys driven by submarine volcanism. An idea I was looking at 10 yrs ago (dibs on the carbon credits, giggles, could make me a trillionaire) this could quickly fill the oceanic gyres of the desolate zones with all the deep benthic and volcano enriched nutrients needed.
  • Good old fashioned blood and bone. Puree krill from the southern ocean and fert the low nutrient desolate zones.

Simultaneous with fertilising the desolate zones we'll need to seed them with the best diatoms and suitable higher temp krill species such as north pacific, common in the sea of Japan. It would be possible to multiply world krill population 100x, to the region of 50 Gtons, making them the biggest living carbon store on the planet

Krill are looking very good for Ocean Fertilization for a number of reasons:

a) Getting phytoplankton produced carbon to seafloor or depth.

- Approximately every 13 to 20 days, krill shed their chitinous exoskeleton which is rich in stable CaCO3.
- Krill are very untidy feeders, and often spit out aggregates of phytoplankton (spit balls) containing thousands of cells sticking together.
- They produce fecal strings that still contain significant amounts of carbon and the carbonate/silica glass shells of the diatoms.

These are all heavy and sink very fast into the deep benthic zone and ocean floor. Oxygen levels are higher down there, and the deep benthic zone is much larger in volume than the rest of the worlds oceans. Besides which, unlike Phytoplankton alone, the spitballs and fecal strings stand a much beter chance of not being decomposed and using up oyxgen. The exoskeletons won't be decomposed at all.

Quote wikipedia: "If the phytoplankton is consumed by other [than krill] components of the pelagic ecosystem, most of the carbon remains in the upper strata. There is speculation that this process is one of the largest biofeedback mechanisms of the planet, maybe the most sizable of all, driven by a gigantic biomass"

b) They can be dried and pressed for krill oil. Krill oil can be used directly for biodiesel or as food suppliments.

c) Dried krill (pressed or not),( and any other biomass) can be pyrolysised for gas, pyrolysis oil for existing power plants, and these can have their flue CO2 fed into algae ponds for negative carbon energy.

- The pyrolysis oil can be used directly for large diesels like ships and heavy machinery.

- The water soluble portion of pyrolysis oil can be used for timber construction adhesive for plywoods, chipboards, and laminated beams etc

- Existing refineries can produce bio-petrols, bio-diesels, and bio-plastics from pyrolysis oil with little modification.

- Pyrolysis also produces biochar, which is terrific fertiliser. Producing soils called Terra Preta that are able to sequester fresh carbon from humus, water and nutrients better than any other soils on the planet, and holding fertility for thousands of years. This is the best and safest way to bury carbon.

d) Krill are delicious nutritious food for humans to replace massively methane emitting beef/sheep/goats and reforest this pastoral land with food-forests and indigenous ecologies.

e) Krill are the best food for a large number of fish and whale species. Putting carbon into living marine biomass is a safe store, and replacing the carbon that we have lost by depleting those stocks.

f) Krill are very efficient phytoplankton harvesters, sometimes reaching densities of 10,000–30,000 individual animals per cubic metre. They quickly swarm to any plankton bloom in the area.

Using them to harvest phytoplankton, and then using simple krill nets on the worlds fishing fleet, is much easier than getting phytoplankton out of the ocean ourselves, as that requires energy intensive centrifuge separation of large quantities of water.

g) Krill Females lay 6,000–10,000 eggs at one time, and they reach maturity after 2-3 years.

- Obviously they can quickly build biomass to any level we can provide food for. Particularly if we are putting them in fresh habitat where small fish that normally consume lots of tiny immature krill are absent.

If we increased the total biomass of krill to 50 Gton fresh biomass as suggested above, that would be about 10 Gton C, then we could remove this amount of Carbon from the ocean every 2 years, this alone has the potential to remove 100 Gton C from the ocean/atmosphere in twenty years.

As krill are such messy feeders, inefficient digesters and shed carbonate rich exoskeletons every 2-3 weeks, they probably would sink to the ocean floor to relatively safely aggregate into sediments, stable carbonate and undecomposed organic carbon around 100 times as much as that. So burying 500Gton C of CO2 in one year would be possible.

Obviously we only need to increase Krill populations by 10x to get the result we need in about 10 years total including the breed up time.

We'd be best to harvest as much as possible to refertilise and replace the carbon in our soils. Remember that about 600 Gton C of carbon from our soils has gone into the oceans already in the last 2000 years.

Thursday, November 29, 2012

A Comprehensive Plan of Action on Climate Change


Threat to global food supply makes comprehensive action imperative
Climate change is strongly affecting the Arctic and the resulting changes to the polar vortex and jet stream are in turn contributing to extreme weather in many places, followed by crop loss at a huge scale.

The U.N. Food and Agriculture Organization (FAO) said in a September 6, 2012, forecast that continued deterioration of cereal crop prospects over the past two months, due to unfavourable weather conditions in a number of major producing regions, has led to a sharp cut in FAO’s world production forecast since the previous report in July.

The bad news continues: Based on the latest indications, global cereal production would not be sufficient to cover fully the expected utilization in the 2012/13 marketing season, pointing to a larger drawdown of global cereal stocks than earlier anticipated. Among the major cereals, maize and wheat were the most affected by the worsening of weather conditions.

The image below is interactive at the original post and shows the FAO Food Price Index (Cereals), up to and including August 2012.

from: Threat to global food supply makes comprehensive action imperative
Apart from crop yield, extreme weather is also affecting soils in various ways. Sustained drought can cause soils to lose much of their vegetation, making them more exposed to erosion by wind, while the occasional storms, flooding and torrential rain further contribute to erosion. Higher areas, such as hills, will be particularly vulnerable, but even in valleys a lack of trees and excessive irrigation can cause the water table to rise, bringing salt to the surface.

Fish are also under threat, in part due to ocean acidification. Of the carbon dioxide we're releasing into the atmosphere, about a third is (still) being absorbed by the oceans. Dr. Richard Feely, from NOAA’s Pacific Marine Environmental Laboratory, explains that this has caused, over the last 200 years or so, about a 30% increase in the overall acidity of the oceans. This affects species that depend on a shell to survive. Studies by Baumann (2011) and Frommel (2011) indicate further that fish, in their egg and larval life stages, are seriously threatened by ocean acidification. This, in addition to warming seawater, overfishing, pollution and eutrification (dead zones), causes fish to lose habitat and is threatening major fish stock collapse.

Without action, this situation can only be expected to deteriorate further, while ocean acidification is irreversible on timescales of at least tens of thousands of years. This means that, to save many marine species from extinction, geoengineering must be accepted as an essential part of the much-needed comprehensive plan of action.

Similarly, Arctic waters will continue to be exposed to warm water, causing further sea ice decline unless comprehensive action is taken that includes geoengineering methods to cool the Arctic. The threat that huge amounts of methane will be released from the warming Arctic seabed makes it imperative to prepare geo-engineering methods to respond to this threat and be ready for rapid deployment soon.

How to avert an intensifying food crisis

As extreme weather intensifies, the food crisis intensifies. Storms and floods do damage to crops and cause erosion of fertile topsoil, in turn causing further crop loss. Similarly, heatwaves, storms and wildfires do damage to crops and cause topsoil to be blown away, thus also causing erosion and further crop loss. Furthermore, they cause soot, dust and volitale organic compounds to settle on snow and ice, causing albdeo loss and further decline of snow and ice cover.

Extreme weather intensifies as the Arctic warms and the polar vortex and jet stream weaken, which is fueled by accelerated warming in the Arctic. There are at least ten feedbacks that contribute to further acceleration of warming in the Arctic and without action the situation looks set to spiral away into runaway global warming, as illustrated by the image below.

Diagram of Doom, with Comprehensive Plan of Action added  (credit: Sam Carana, October 9, 2012)



To avert an intensifying global food crisis, a comprehensive plan of action is needed, as also indicated on the image. Such a plan should be comprehensive and consider action in the Arctic such as wetland management, ice thickening and methane management (methane removal through decomposition, capture and possibly extraction).

A Comprehensive Plan of Action on Climate Change

A Comprehensive Plan of Action on Climate Change needs to include policies to achieve a sustainable economy, as well as adaptation policies.

Such a comprehensive plan is best endorsed globally, e.g. through an international agreement building on the Kyoto Protocol and the Montreal Accord. At the same time, the specific policies are best decided and implemented locally, e.g. by insisting that each nation reduces its CO2 emissions by a set annual percentage, and additionally removes a set annual amount of CO2 from the atmosphere and the oceans, followed by sequestration, proportionally to its current emissions.

Policy goals are most effectively achieved when policies are implemented locally and independently, with separate policies each addressing a specific shift that is needed in order to reach agreed targets. Each nation can work out what policies best fit their circumstances, as long as they each independently achieve agreed targets.

Cuts in CO2 emissions of 80% by 2020 can be achieved by implementing local policies focusing on specific sectors (such as energy production, transport, land use, waste, forestry, buildings, etc).

As an example, each nation could add fees on jetfuel. Where an airplane lands that comes from a nation that has failed to add sufficient fees, the nation where the airplane lands could impose supplementary fees and use the revenues to support methods that capture CO2 directly from ambient air. Such supplementary fees should be allowed to be imposed under international trade rules.

Some policies will need to continue beyond 2020, in order to bring down levels of greenhouse gases in the atmosphere to their pre-industrial levels this century, i.e. getting CO2 in the atmosphere back to 280ppm, CH4 back to 700ppb and N2O back to 270ppb. Policies can be very effective when focusing on local sectors such as agriculture and buildings, while also supporting geo-engineering methods such as biochar, enhanced weathering and direct capture of carbon from ambient air.

In addition to such policies to achieve a sustainable economy and adaptation policies, further geo-engineering methods will be needed to avoid runaway warming, as indicated in the blue area of the image below.


Arctic Methane Management

At the original post, some of the areas in these images can be clicked on, for examples or more background. The box for Additional Arctic Methane Management on above image is further worked out in the image below, which highlights the need for geo-engineering methods that focus on methane, a component of the plan that needs to be given far more attention. Again, support for such methods could be agreed to proportionally to each nation's current emissions.

Monday, November 14, 2011

Combining Policy and Technology


Technologies to remove carbon dioxide from the atmosphere

The Virgin Earth Challenge is a prize of $25m for whoever can demonstrate to the judges' satisfaction a commercially viable design which results in the removal of anthropogenic, atmospheric greenhouse gases so as to contribute materially to the stability of Earth’s climate.

Among the 11 shortlisted organizations are:
Above three technologies (biochar, carbon air capture and enhanced weathering) have great potential to help out with carbon dioxide removal (CDR) from the atmosphere. To combat global warming, further technologies should be considered, such as in Solar Radiation Management (SRM) and Arctic Methane Management (AMM).

How effective each technology is in one area is an important consideration; importantly, each such technologies can also have effects in further areas.

Further areas

Global warming is only one out of multiple areas where action is required; an example of another area is the hole in the ozone layer over Antarctica; effective action has already been taken in this area, but the growing hole in the ozone layer over the Arctic shows that further action is necessary.

A safe operating space for humanity is a landmark 2009 study by Rockström et al. It identifies nine essential areas where sustainability is stressed to the limits, in three cases beyond its limits.


Areas and applicable technologies

The table below shows these nine areas on the left, while technologies that could be helpful in the respective area feature on the right.

As said, each of technologies may be able to help out in multiple areas. As an example, by reducing carbon dioxide levels in the atmosphere, biochar and carbon air capture can also indirectly reduce carbon dioxide in oceans and thus help out with ocean acidification. Enhanced weathering could additionally reduce carbon dioxide in the oceans directly, thus presenting itself even more prominently as a proposal to achieve sustainability in this area.

Similarly, algae bags located in the mouth of a river could help out in multiple areas. They could produce biofuel and thus help reduce aviation emissions, while in the process catching fertilizer runoff, thus reducing emissions of nitrous oxide (the largest ozone-depleting substance emitted through human activities in a 2009 NOAA study) and also reducing depletion of oxygen in oceans.

1. Climate ChangeCDR: biochar, carbon air capture, enhanced weathering, algae bags, EVs, renewable energy, clean cooking & heating, LEDs, etc.
SRM: surface and cloud brightening, release of aerosols
AMM: methane capture, oxygen release, river diversion, enhanced methane decomposition
2. Ocean acidificationenhanced weathering
3. Stratospheric ozone depletionoxygen release
4. Nitrogen & Phosphorus Cyclesalgae bags, biochar, enhanced weathering
5. Global freshwater usedesalination, biochar, enhanced weathering
6. Change in land usedesalination, biochar, enhanced weathering
7. Biodiversity lossdesalination, biochar, enhanced weathering
8. Atmospheric aerosol loadingbiochar, EVs, renewable energy, clean cooking & heating, LEDs, etc.
9. Chemical pollutionrecycling, waste management (separation)

Implementing the most effective policies

Policy support for such technologies is imperative. Just like some technologies can help out in several areas, some policies can cover multiple areas. As an example, a policy facilitating a shift to cleaner energy can both reduce greenhouse gases and aerosols such as soot and sulfur. Sulfur reflects sunlight back into space, so reducing sulfur emissions results in more global warming, but conversely global warming can be reduced by releasing sulfur over water at higher latitudes.

How many different policies would be needed to support such technologies? What are the best policy instruments to use?

Traditionally, government-funded subsidies and standards have been used to contain pollution, sometimes complemented with levies and refundable deposits; this can also work for chemical pollution. Standards have also proven to be effective in reducing the impact of CFCs on the ozone layer, while - as said - policies could at the same time also be effective in other areas, in this case reducing the impact of CFCs as greenhouse gases.

However, standards don't raise funding for support of such technologies, while taxpayer-funded subsidies make everyone pay for the pollution caused by some. Hybrid methods such as cap-and-trade and offsets are prone to corruption and fraud, which compromises their effectiveness. Local feebates are most effective in facilitating the necessary shifts in many areas.

Two sets of feebates

To facilitate the necessary shift away from fuel toward clean energy, local feebates are most effective. Fees on cargo and flights could fund carbon air capture, while fees on fuel could fund rebates on electricity produced in clean and safe ways. Fees could also be imposed on the engines, ovens, kilns, furnaces and stoves where fuel is burned, to fund rebates on clean alternatives, such as EV batteries and motors, solar cookers and electric appliances. Such feebates are pictured as yellow lines in the top half of the image below.

Support for biochar and olivine sand could be implemented through a second set of feebates, as pictured in the bottom half of the image below. Revenues from these feebates could also be used to support further technologies, as described in the paragraph below.

Further technologies should be considered for their effectiveness in specific areas, including:
  • release of oxygen to help combat methane in the Arctic and to help combat loss of stratospheric ozone
  • use of plastic sheets to capture methane
  • use of radio waves to enhance methane decomposition
  • diversion of water from rivers to avoid warm water flowing into the Arctic Ocean
  • release of aerosols over water at higher latitudes
  • surface & cloud brightening to reflect more sunlight back into space



Professor Schuiling proposes olivine rock grinding


Dutch Professor Olaf Schuiling has been working on rock grinding for many years. Remember the Virgin Earth Challenge, launched early 2007 with the promise to award $35 million to the best method to remove greenhouse gases? Schuiling said: Let's grind more rocks! Last thing Schuiling heard was that he was among the final ten contenders.
Schuiling's method is simple. Crush olivine rock to small pieces and it will bind with carbon dioxide. This process - called weathering - happens in nature but takes a long time. Crushing and grinding olivine rock will speed up the process and is therefore often called enhanced weathering. It works best in wet tropical countries, but can be done everywhere around the world.
Schuiling proposes to cover beaches, levees and railway tracks with the material, and proposes olivine to be added to building materials like pavement and concrete. It can also be added to soil and water. Adding olivine can fertilize the soil and improve its ability to retain water, and can work well in combination with biochar and other ways to increase organic carbon in the soil. When added to the sea, it can reduce acidification, and stimulate growth of diatoms and other forms of biomass in the sea.
This is a win-win solution, Schuiling says, as it helps grow more food, while combating global warming. To add another win, it can also produce drinking water that is healthier than rain water. Schuiling recommends cities to build olivine hills, to remove carbon dioxide from the air while filtering water.
There's is a video with more background, in Dutch with English subtitles. Also have a look at this poster.

Comments


What works best is implementation of feebates that put in place combinations of local financial incentives and disincentives, as illustrated by the image on the right.

Energy feebates, working in a parallel yet complimentary way, can clean up energy supply within a decade, while feebates as pictured above can continue to bring carbon dioxide levels in the atmosphere back to 280 ppm, as well as bring down carbon dioxide levels in the oceans.

Rock grinding should be part of a comprehensive policy that also includes replacing fuel with renewable energy and support for biochar. The latter is also discussed in the posts Biochar and The Biochar Economy.

As the above diagrams try to show, biochar and olivine sand can be combined in soil supplements, to help bring carbon dioxide levels in the atmosphere back to 280ppm. Rebates could be financed from fees on nitrogen fertilizers, livestock products and Portland cement.

Enhanced weathering is possible with other types of rock, but more easily done with olivine. The paper Olivine against climate change and ocean acidification includes the map below with the global distribution of dunite massifs. By removing their lateritic overburden, the underlying dunites (rocks that consists of > 90% olivine) can be mined. 

As the image on the right shows, there's no need for long distance transport. One dot often represents several dunites and olivine is available in abundance at many places across the globe.

The benefits are great and this looks like one of the most economic ways to bring down carbon dioxide levels. 

The energy can come from wind energy, which is clean, price-competitive and available in abundance in many places. Rock grinding, the transport and distribution can be largely automated, and take place predominantly at off-peak hours, while wind energy can be supplied very economically at off-peak hours.

Olivine sand can also be combined well with biochar, as soil supplement. Have a look at the post the Biochar Economy.




Further reading:
Feebates
Biomass
Carbon Air Capture and Algae Bags
Enhanced weathering
Oxygenating the Arctic
Ozone hole recovery
Enhanced methane decomposition
Desalination
Vortex towers could vegetate deserts
Carbon-negative building
LEDs: When will we see the light?
Thermal expansion of the Earth's crust necessitates geo-engineering
Towards a Sustainable Economy
The way back to 280 ppm

Thursday, September 22, 2011

Carbon-negative technologies


The image below, adapted from Negative Emissions Technologies report by Duncan McLaren (version 2, 2011), pictures a number of carbon dioxide removal (CDR) methods. 





For further discussion of biomass use, see the post Biomass; for further discussion of policy issues, see The way back to 280 ppm and Towards a Sustainable Economy