Carbon Sequestration by Leaves and Dead Plants Carbonisation

To prevent the catastrophic effects of global warming, as explained in the previous post “How much does switching to totally clean energy cost?” we need to use two general approaches:

  • stopping future greenhouse gas emissions (which is best done by stopping the burning of fossil fuels as explained and significantly reducing meat & dairy consumption, as well reducing food waste)
  • removing existing greenhouse gases from the atmosphere, down to a stable level (around 350ppm).

In many previous posts, I’ve already discussed how to tackle the first point. In this one, I will propose alternative ideas on how to deal with removing greenhouse gases from the atmosphere.

This idea is about a year old. Some recent findings confirmed the idea’s validity. Only the last part about the government payment of subsidies has been added recently, as a very viable booster. In my knowledge, no one has tried something like this before — at least not in the way I will describe here.


Overall CO2 emission could be reduced by collecting fallen leaves and dead wood (dry and fallen branches and woods) from the forests around the world, then drying them out and processing them either into building materials (boards, beams, furniture...) or into charcoal, activated carbon, graphite, and graphene for multipurpose use but most significantly for batteries.
To boost the schema, governments should start paying people to stop cutting forests and instead collect foliage, dead wood, and plants, processing it into activated carbon that can be used in batteries, which would create additional profit and speed up switching to clean energy, preventing future carbon emissions.


Before I explain this model in depth, I will introduce a few basic concepts that will help you understand this idea better. Bear in mind that those concepts won’t be explained in detail, although links are provided for future reading. If you have questions, strong opinions or arguments against those just by reading my short explanations, I suggest reading those papers in full, as my short explanations may be misleading.

The following components are used as pillars for the model:

1. Seasonal cycle of CO2 concentrations in the atmosphere

Each year, CO2 levels rise from around October to May and it falls a around every May to October.

Recent Monthly Average Mauna Loa CO2 - NOAA 

This saw tooth pattern is called a Keeling Curve. The reason for this is that “the leaves on the trees drop in the fall, the leaf litter and other dead plant material break down throughout the winter, thanks to the hard work of microbes. During this decomposition, microbes respire and produce CO2, contributing to atmospheric CO2 levels in the process.” [1] In May, when plants turn green again, with the help of sunlight and photosynthesis, they pull the CO2 from the atmosphere.
The Keeling Curve process of rise and decline of CO2, in the way it is, depends mostly on the Siberian and forests across the Northern Hemisphere. Most rainforest trees stay evergreen, and, in the Southern hemisphere, there isn’t much land or trees.

2. Carbon sequestration via wood burial

Ning Zeng, in his paper from 2008, explained an idea to sequester large amounts of CO2 by burying dead, old, and selectively cut wood, in order to extend wood decomposition and create carbon deposits. Forest cleaning and thinning forests would make them healthier and younger, avoiding wildfires, especially when followed by immediate reforestation.

3. Payments for ecosystem services to reduce deforestation

Seema Jayachandran took a different approach to tackle global warming: preventing deforestation (responsible for up to 15% of global CO2 emission [2]) by giving monetary incentives to forest owners, if they keep their forests intact. Trials done in Uganda have shown significant benefits. [3] [4]

4. Carbon battery

For years, I am actively following the development of new technologies. Among them, one of the crucial ideas is energy storage. In recent years, Li-Ion batteries have become the storage with the largest media coverage, but there are a few issues with Li-Ion batteries. Although Li-Ion batteries have a relatively good weight-to-energy storage ratio (which is very important from the perspective of usage), they are flammable, not recyclable, have a relatively modest cycle life (2000 cycles), and it takes a very long time to charge them.

A recent, equally-captivating technology is super-capacitors. By super-capacitors I especially have in mind all-carbon batteries that come in many variations: activated carbon batteries, dual carbon batteries, and graphene batteries.
Super-capacitor batteries have very short charge times—measured in seconds and minutes, instead of hours—have a very long cycle life (100,000 cycles), they are very recycle-friendly (it is possible just to disassemble them, put active material in the ground, and it will help plants grow), and they are not flammable, but, unfortunately, they have smaller capacity than Li-Ion batteries.
The smaller energy-to-weight ratio is not a huge obstacle from the perspective of residential energy storage; if we consider its phenomenally fast charging, this makes it useful for cars and other vehicles (despite shorter range, they could refill much faster, in 5-15 minutes).

It is important to mention that development of carbon super-capacitors started very early: since the 1950s, it has been lead by General Electric engineers, and the earliest mentions of a dual-carbon battery can be found in patents US3844837 (A) from 1974 and US 4830938 A from 1989 but recently a Japanese company perfected the chemistry [5][6]
Today, many researchers and open source communities are actively working on different types of chemistries for this type of energy storage, continuously increasing its ability to store larger amounts of energy.

5. New process converts biomass waste into useful electronic devices

Chinese scientists have found a very simple way to convert tree leaves into activated carbon material for the super-capacitor batteries, with capacities exceeding those seen in graphene super-capacitors—basically, in that way, converting huge amounts of waste into very useful products.

6. Sea Weed to fight climate change

Using fast-growing seaweed farms could tackle climate change, and seaweed could be used as food to give us necessary minerals. It also could be processed as activated carbon material for the batteries the same way tree leaves are processed. [7] [8]

7. Picking right trees

Some trees will react better and some worse on climate change; in order to effectively fight climate change, we have to pick and plant the most resilient, fast-growing trees that will help us to stabilise global warming in the next 10 to 50 years. [9]


If we look closely at the Keeling curve, we will notice that the main issue is seasonal difference between sequestering and emitting CO2. The season when plants are fully grown, green, and able to sequester CO2 more than it is emitted lasts only 4 months (from the end of the May to mid-to-end of September), while plant degradation & harvesting and soil preparation period lasts 8 months. Equally, man-made CO2 emission will fluctuate during seasons, depending on energy requirements.

It is obvious that we must significantly reforest large portions of Earth with fast-growing, fast-sequestering plants (that would, if possible, stay evergreen during the entire year), continually taking CO2 out of the atmosphere, if we intend to make any meaningful impact on climate change.

Even if we convert to 100% clean energy tomorrow, other sources of greenhouse gases (meat & dairy production, landfills, deforestation, wildfires...) could tip climate change past the point of no return, so those things should be addressed promptly.

Over many years, land plants and sea life created a balance between how much CO2 is emitted and sequestered over the year. But, since the beginning of the Industrial Revolution in 1760, with significant changes in our lifestyle, humans have released huge amounts of CO2 by burning coal, gas, and oil stored in earth’s crust for millions of years. Additionally, farming animals on scales that could be counted in billons just made all those things worse.

The general idea behind the model I am presenting here is to temporarily (over the next 10 years or a bit more) change the balance in favour of sequestering, so that natural emission, which accounts for 90% of all emissions, would slightly but continuously decrease, allowing the natural environment to pull more CO2 from the atmosphere than is emitted in a typical year. [10] [11]

The modelled global Net Primary Productivity (NPP) says that, out of a total 57 GtC a year, 19 GtC per year goes into dead leaves, 17 GtC per year into dead wood, and 21 GtC per year to dead root structures.

We could prevent decomposition and therefore block significant portions of those emissions by collecting foliage, dead branches and trees, shrubs, dead grass, and other materials and convert them into useful products.

Processing foliage into activated carbon, graphite, and graphine (all stable forms of carbon) would starve microorganisms, partially preventing the natural emission of carbon dioxide (CO2) and methane (CH4) by microbial decay, allowing plants to pull more CO2 from the atmosphere.

Without materials decomposing, natural CO2 emission would be reduced significantly, as plants continue to pull CO2 from the atmosphere.


Bearing in mind the main purpose of reversing climate change, there are few more benefits.

1. Building material

Harvested leaves and dead wood could be used instead of sawdust for creating plywood or laminates that could be used in the building and furniture industries. Biomaterials locked in building material will be durable, long lasting, and also lock carbon inside, preventing further emissions.

2. Wildfire protection

Harvesting leaves and dry/decomposing wood could prevent wildfires that just this year (2017) turned to ashes more than 4 million acres (1.6 million hectares) 7 million acres (2.8 million hectares (most recent calculation)) across Chile, Portugal, Canada, U.S., Russia, Australia, and many others.

We have to do as much as possible to prevent future fires, as they are significantly adding to the problem and additionally crippling the sequestering ability of the planet. Fragmenting, thinning forests, and cleaning dry biomass (leaves, grass and wood...) could make forests healthier and make them more resilient to wildfires.

3. Carbonising bio material

By carbonising bio material into solid carbon forms (such as charcoal [biochar], activated carbon, graphite, and graphene), we could store carbon safely (bury, shelf, pile) without worrying that it will react with oxygen, thus forming CO2 and escaping back to the atmosphere.

4. Using CO2 from the carbonisation process for enhancing plants growth

During the process of carbonisation of leaves, dead wood, and other plants, emitted CO2 could be captured and used for growing food by greenhouse carbon dioxide enrichment.

At this point, hydroponics with a water- and air-enriched environment could be used to grow plants and algae, such as a fast-growing kelp. Depriving plants of soil would limit their ability to pull carbon from the ground. Also, it would be easier to control nitrogen content in a closed-vertical farm environment, therefore avoiding nitrogen pollution of rivers and lakes.

5. Creating super-capacitor batteries!

Most importantly, activated carbon and other forms of carbons can be used as active materials for super capacitors. With a project of such a large magnitude, already cheap, activated carbon would become more available and very cheap. That means that we could build inexpensive battery storages, on a large scale, storing energy and locking (sequestering) carbon for a long period of time.

If we could minimise production lines in the process, so they could be available for small communities or private owners—similar to 3D printers—we could open a huge market and, by distributing manufacturing by democratising technology, make the entire endeavour doable on a large scale in a short time.

Even with 3 times less energy density (although current 284 Farads/gram - 367 Farads/gram would make energy levels of 120Wh/kg - 180 Wh/kg, which is the bottom level of Li-Ion batteries), this concept would be cost effective and doable and very competitive against Li-Ion batteries without increasing storage size significantly, in comparison with space available and the benefits added (charge speed, cost, longevity, recyclability...)

Large supplies of battery-grade activated carbon will additionally drawdown the price, making battery storages very cheap and widely available for any purpose, home or industry. In that way, 100% electrification and switching to all clean energy sources could be achieved at a much faster rate.

Even now, I can envisage that it would be possible to satisfy 100 percent of energy storage requirements in a period of 5 to 10 years.

6. No additional space required

Instead of woods, as suggested by Ning Zeng, we could bury batteries into the ground.

The entire buried energy storage could be, for instance, enveloped by a slow biodegrading “placenta”, after 30 to 50 years of usage (although 100,000 cycles, if we cycle storage twice a day, would mean a life of 135+ years) we could either pierce the placenta, or it would naturally decompose, so that plant and microorganisms could start decomposing old batteries. Although this nature-friendly way looks nice, it is not necessary, as there is a huge number of abandoned mines and tunnels around world that can serve the future purpose of locking up carbon, instead of the fossil fuels we have burned over time.

Furthermore, activated-carbon batteries could be used as building bricks. Instead of using cement, clay or wooden frames, we could have power bricks and true power walls. Being fire retardant, they would be completely safe and additionally play an energy-storing role in residential and commercial properties.

7. Reduction of rejected energy waste

Large-scale energy storages will further increase the energy efficiency of the electric grid, reduce electricity waste, and further decrease CO2 emission. Currently, we waste 60% of all energy, mainly due to the inefficiency of combustion engine motors and power plants that must run on idle, in order to run the electric grid. All of that would change with large-scale, distributed energy storages.

8. Utilisation of surplus energy and exotic energy sources

With the implementation of all the above, excess energy from clean energy sources, as well as exotic sources—such as lightning storms, excess water from hydro power plants, or power from excess winds (wind turbine are frequently shut down, if production is higher)—could be harnessed and safely stored for later usage or/and we could power giant machines for sucking carbon directly from the air.

9. Further economic potential of solid carbon forms

Activated carbon has significant economic potential, as it is used in industrial, medical, analytical chemistry, environmental, agriculture, distilled alcoholic beverage purification, fuel storage, gas purification, chemical purification, mercury scrubbing, and many other applications. It has a well-known ability to purify air and water, removing toxins and fighting molds and pathogenic microorganisms.


1. Top soil and nutrition

This technique shouldn’t be applied on a large scale for a long period of time; having in mind that mulch is responsible for creating top soil and, by the process of microbial decomposition (especially nutrition rich leaves), gives nutrition to plants, insects, and different animals in the chain, supporting healthier soil. [12]

Decomposition is also very important for fungi development, and they have a significant role in trees’ lives, helping them to absorb nutrients and to communicate with other trees, creating healthier forests that can fight diseases.

In order to prevent those, supervision may be necessary, as well as some form of partial collection and rotation on annual bases, in order to prevent starving the same area for a long period of time.

2. Wildlife impact

When we start “harvesting” foliage from Northern Hemisphere forests on a large scale, tests should be done promptly, in order to find unknown impacts, especially those on wildlife and intact animal habitats. Specialists for the specific fields (forestry, ecology, biology...) should be employed, in order to assess the overall impact on nature.

3. Reforestation Challenges

Newly-planted trees need years to reach maturity, in order to start sequestering the highest amount of CO2 and locking them in wood mass. In our best estimates, we have only 10 years or less to perform significant actions. Aside from collecting leaves and dead biomaterial, we need to apply additional measures like reforestation fast and on a large scale, in order to capture atmospheric carbon and store it within wood mass. That will keep carbon locked over relatively long periods of time. This is a significant challenge, as it creates competition between agriculture and forestry. One way to overcome this is vertical farming, supplying energy needed from surpluses from clean energy sources, growing food more efficiently, and allowing woods to take over land.

4. Accessibility challenges

The foliage collection approach has significant logistic and accessibility issues. Northern Hemisphere forests—mainly those in Siberia, Canada, and northern parts of United States—are largely unpopulated areas and usually inaccessible by standard transport means and the network of forest roads.

This would make the entire endeavour very difficult but not impossible. New roads, railways, or even hyper-loop transportation would need to be built, in order to create stable networks for supplies. Also, certain numbers of people who would be employed for tending those forests would need to populate those far-away locations. Creating additional networks of roads would also encourage illegal deforestation.

On the positive side, networks of roads would protect forests from fast-spreading wildfires.

Why would this approach work?

A crucial component of this idea is making profit and also creating wealth. This concept has large economic potential, allowing individuals and micro-cooperatives to create valuable business, instead of focusing on large corporations. By reducing the poverty rate, a more stable society will be created, with more people that care about nature and one another.

Unlike other suggested methods—such as power plant CO2 capture or sucking carbon directly from the air and then using geological or basalt storage—that all include significant expense, this method actually has huge earning, investment and value creating potential — allowing people to (do what people do best) compete and collaborate seeking profit.

Zeng estimates that, with the sequestering cost set at $50/tC for wood burial, this would require $250 billion per year at a 5 GtC/year sequestration rate. Just this year, hurricanes Irma and Harvey made an estimated economic cost of $290 billion.

Just for comparison, a $300 billion yearly investment would mean adding 6 million jobs at a rate of $50,000 per year. That many jobs would be more than enough to carry out the necessary work, and, in many places in the world people would not be paid that much.

So, instead of letting nature run wild and create loss, the leaf-activated-carbon processing method would make a significant profit for all parties in the chain and increase the overall World’s GDP.

Along with fixing global warming, this method would have a huge positive effect on the economy, creating millions of different new jobs for people that will tend forests (clean, re-grow, make plans, monitor, partition...), dry biomass (dead wood, leaves, dry grass, and bushes), process biomass into activated carbon, create kilns (micro, mini, mid, large), work on production lines for batteries, make sun ovens for biomass drying, and many other different machines.

How do we boost the schema and succeed on a global scale?

Here comes professor Seema Jayachandran’s idea about paying people not to cut forests, which could be renamed a subsidy for leaves harvesting.

By harvesting leaves and dry grass, people could actually start caring more about trees while they are alive, as they could see trees as a long-term asset, instead of one of gain obtained by selling wood as building or firewood material.

By this, people who own forests or just tend national forests under the supervision of rangers could have multiple revenue streams. Firstly, they will earn money by not cutting trees via the forest preservation subsidy. Secondly, they could get money from selling leaves to nearby processing facilities, or they could process dead biomaterial on their own into activated carbon that could be sold as multipurpose products. Continuing along these lines, they could buy the ‘battery micro production lines’ and sell the battery storages.

Except for grants and subsidies, the government will probably have an additional supervisory role. With time, some kind of quality control and grading of activated carbon by flake size, electrical conductivity, quality, porosity, etc. will need to be formed.

The supervisory role will also extend to illegal tree cutting, especially for those that receive subsidies for forest preservation.

Everything else would be left to the market to balance itself on its own.

Update: 2017 Sep 22

Question & Answers

How is this different from the biochar idea?
Biochar is just part of the story, or you can consider it as a subset of this method. Biochar is basically charcoal, but that specific term is used for expressing a specific purpose of utilization: as an adsorbent or a soil amendment. Biochar is made in the same way as charcoal, mostly from cutting down trees.
On the other hand, this method has shifts our mindset, so that we start considering live trees as a commodity that is more valuable if it is alive, so we could use it multiple times, not as a one-off product.
In other words, this method is all about saving trees.

Why is the project location Siberia? (challenge comments question)
The project location is not limited to Siberia; actually, the project location is the entire world—or, to be more specific, temperate forests (USA, Canada, and many others), or any other forest that has dry grass or dead wood (dry branches, fallen trees, etc.).
Limitations of the WhatDesignCanDo user interface do not offer the option to select “World”.
The reason for choosing Siberia is because the largest influence on the Keeling curve is Siberia; you can read more about it here: “Why are Seasonal CO2 Fluctuations Strongest at Northern Latitudes?

There is nothing new about this idea.
It is true! All components (trees, leaves, charcoal, and batteries) are already known, but I connected them in a unique way to work as a unit, solving multiple issues at the same time.
We could think about it in this way: the words we use to write are all already known, and we rarely invent new ones, but how we connect those words matters, as we create new, unique stories.

Have you heard the idea of using deep sea kelp farms to move carbon to the bottom of the ocean? (Twitter question)
Yes, I have, and I did mention it in as an additional method. The reasons I am placing it as a side project are the magnitude of work and economic feasibility. Fallen leaves are already there; nothing is needed to obtain the described amount (that will, by the way, emit 19GtC each year), we just need to collect 5GtC (1/4 of all fallen leaves), transform it, and use it. The battery route in this idea is all about the profitability part, along with all other uses of activated carbon. Using inexpensive battery storages, we would reduce energy losses even more and cut CO2 emissions at the source.
On the other hand, kelp needs to be seeded and grown. There is an economic value in it, as it can be used as feed for humans and cattle, reducing methane from enteric fermentation, it can be turned into charcoal, then later turned into activated carbon, and later on into batteries.
Some types of Kelp algae can grow as fast as half a metre a day, and that is good.
However, to grow a field that can pull 5GtC is a significant job that needs time.
Again, I am not excluding this method, but I am considering it a side project, until it becomes large enough that we do not need to use forest leaves anymore.

What is your biggest reason for going with this method?
The biggest points for solving the climate change issue (or any other issue) are these: how economically viable something is, how easily we can do it, and whether we can solve multiple issues at the same time.
This approach can remove fire-starting fuel partly responsible for spreading wildfires, can reduce natural CO2 emission of leaves (dead wood/plants, dry grass) decay, can open possibilities to numerous industries (water filtration, electricity storage), could create huge numbers of jobs worldwide (energy, forestry, road building, housing, furniture), could reduce waste energy and therefore further remove CO2 emission, can use abandoned coal mines for storage, could make continuous-charging while driving on roads feasible (reducing size of battery in cars), and could create a network of decentralised energy storages that can help in disaster relief situations when the grid is down.

Collecting leaves would pose and create massive damage to wildlife (bugs, insect, animals, plants).
I am aware of the damage part, but I am also aware that we lost more than 4,000,000 acres of woods due to wildfires, just this year, and, while I am writing, some U.S. forests are still burning.
Those forests are gone—turned to ashes, along with all the wildlife.
So, between this method and wildfire’s total damage, I would rather choose the one that can minimise damage and solve issues for later years. As I mentioned, this schema is not a permanent solution; it is like medicine: it is bitter, but it helps you to get better, and you have to do it for a certain period of time.
On the other hand, damage can be minimised further by collecting leaves and dead wood in patches (similar to chess fields) or in strips parallel to road alignment. If we rotate collection by strips, collecting leaves from marked fields (done by forest rangers) every 4 years, the damage would be additionally reduced.
Strips would have advantage over fields for wildfire protection, as they would divide forests along with networks of roads that would need to be built. Also, we could collect leaves only during certain days; in autumn, if leaves are collected only for the first few days of leaf foliage, the remaining leaves, still hanging from the trees, would fall later and would remain on the ground.

During hot days, it would be good to trim and collect dry grass, leaves, and dead plants that can easily spread wildfire but can be equally used as activated carbon.
There are some dangers connected with this method, but nothing in comparison with the total damage climate change can do if it remains unchecked.


On 22nd September 2017, this idea was approved for the The Climate Action Challenge. The link for submission is here:

1. Relevance
This idea tends to fix Climate Change issues for all people, not just those who are currently affected.
It is global solution that can significantly reduce CO2 emission, hopefully reducing temperatures, open new jobs and industry opportunities, provide for families, protect forests from deforestation and wildfires, and probably more, yet unseen benefits.
Just this year, raging wildfires and hurricanes showed us just a fraction of the damage that global warming can do. If we do not do anything, it will just get worse. It is worth having in mind that just part of this year’s damage costs would be enough to cover the cost of entire schema worldwide, in the process creating value and savings that would exceed the cost multiple times over.

2. Impact
This idea can have a huge impact; some metrics are measurable, and some are not. Although it is possible to measure economic benefits and savings, we cannot measure potentially-prevented wildfires and hurricanes. One acre of forest needs at least 15 to 25 years for full growth; now imagine losing 4 million acres, and imagine how many people we would need to seed an area that big with new trees.
The most important aspect of this idea is saving lives in the long run.

3. Feasibility
We have all the technology we need to do this. The idea is economically viable and cost effective. Profit can drive it. Large numbers of countries could enjoy direct economic benefits from this, and all countries would benefit from reducing the effects of climate change. Legally, this idea does not interfere with existing laws and has a huge economic potential, with the ability to lift people from poverty. This is a significant social and psychological effect. Lastly, it can help connect people together, collaborating toward the mutual goal..

4. Scalability
This method is scalable and, with enough initial investment, it could be implemented at an exponential pace. It could be implemented on small scale, just helping local people, but, equally, it could be implemented globally, covering the entire world.
There are different approaches on how to make this idea happen. Ideally, people should collaborate with governments. Government departments of roads and forestry would be appointed for planning networks of roads and marking/planning areas (strips) for collection (cleaning). All people will have an equal opportunity to collect and invest in processing and battery production lines.
Our idea is to give the ‘know how’, making the designs of tools available online, minimising production lines for processing equipment, making it cheap and widely available to a larger percent of investors.

5. Excitement
Is this idea exciting?
It is for me, knowing that it could reduce climate change effects globally and potentially solve global warming—giving us additional time to switch to clean energy sources. It is exciting to think that we could live in unpolluted cities, have healthier lives, and live without fear that hurricanes and wildfires will destroy our homes. It is exciting that the same idea can optimise our energy usage, create economic value, and help distribute wealth at the same time.
Is it exciting for other people?
They will show it by how much they think, talk, and are willing to share this idea with others.

6. Commitment
We are already planning future steps—thinking about the tools and connections necessary to test this schema as soon as possible. Securing additional funds will just increase our velocity proportional to the amount of the funds we can secure, making this idea viable on a larger scale much faster.

Update: 2017 Sep 24

Today should have been my offline day, but as soon I started meditating I realised there are few more things to add.

Is there anything we can do about methane releasing from oceans and thawing permafrost in Arctic Circle?
There is one side effect of this method I have not though about untill this point, it could help slowing melting of the permafrost in Arctic Circle (Alaska, Canada & Siberia). By building network of roads for the purpose of tree leaves collection, it would be possible to use much easier method of two Russian scientists Sergey Zimov and Nikita Zimov to compress snow by moving heard of animals during winter days. Way the method works is by compressing snow is becoming thinner but much denser and it takes more time to melt.

Secondly, we could use methane extracted from landfills (by for instance inserting long pipes), to run ovens that would carbonise leaves. In that way we would save energy, and at the same time convert more potent green gas methane CH4 in to less dangerous CO2. (methane’s Global Warming Potential is 25-75 time bigger than CO2).

Unfortunately, unless we start cooling planet or making artificially contained hurricanes that will dissipate oceans heat back to space, there is not much we can do about the methane bubbling from oceans. So, for now regarding ocean methane all I can think of is using all above mentioned methods to lower down overall CO2 and therefore cool down the planet, which would consequently slow down melting of of the permafrost and methane clathrate.

Would converting huge amounts of leaves into activated carbon for batteries take huge amounts of energy?
It is important to emphasise that main idea is to lock 5 Giga tons of Carbon each year so it won’t escape to atmosphere. That being said, there are multiple way we can dry leaves and use them in furniture industry as plywood/compressed wood, as base for paper, or in cardboard industry. We should also take into account multiple uses of activated carbon for filtration and how can help us to clean our waters and remove broad range of pollutants.

But, let’s consider batteries. Below in table you will find typical content of the Li-Ion battery. To simplify calculation we will approximate that typical content of carbon in one 18650 cell is 10 g (in table entire cell weight is 40 g, but typically 18650 cell weight is around 45 grams).

Using Chinese method we need to apply 220 C for 12 h and then few short spikes between 450 and 800 C this is more to activate already made carbon that is mixed with potash (potassium hydroxide).
So, we will take that the oven is going to use 3 kW of energy per hour and while we put 2 kg of crushed leaves inside of the oven (leaves are very light and can take significant volume).
That means that we would use 36 kWh of energy starting with 3000 grams of leaves and ending with 1500 grams of approximately carbon (depending on tree type content of carbon in leaf can range between 50 to 65% ).
That means energy need would be 24 Wh per 1 gram of carbon, whih would mean cost of around $2880 per metric ton. Current cost of activated carbon depending on properties can range from $500 – $5000 per metric ton.

Looking from perspective of single 18650 energy cost would be (10 g x 24 Wh x 12 cents ($) per kWh) is 2.88 cents per cell.

Tesla 14 kWh power wall battery costs £5,900 (~$8000). Knowing that Tesla 85kW car battery has 7104 cells, we can calculate that there are 1170 cells in power wall, which means that there is 11.7 kg of carbon. We said that all carbon battery as powerful as Li-Ion battery from the perspective of energy storage so we will consider we need 3 times as much or 35.1 kg of carbon for equally powerful energy storage.

That means the cost of the carbon in that storage would be around $101.08.

Please note that breaking leaf bonds and turning it into carbon depends a lot of how efficiently we can convert it, if we could put double of that amount in the oven or use less time or any other efficient way price would drop significantly. Also note that we have not calculated price of leaves collection, which would be partially subsidies to prevent tree cutting.
Let’s go back one step back what we said about methane if we would use inexpensive methane CH4 from landfills, that cost would significantly drop, plus we would as I said convert it into CO2 which is less dangerous, and as we burning methane in controlled environment we could feed algae’s with captured CO2.
Additionally, it would be possible to make large sun dryer and concentrated sun ovens that could do the same job quite inexpensively.

Few more things about batteries
It is important to have in mind following:
Recyclability & Life – or how easy or complex is to recycle battery after its life, and how frequently we need to do it or in other words what is battery life. For instance all carbon batteries are much easier to recycle than Li-Ion batteries, and they also have significantly larger life cycle (Li-Ion 1500-3000 cycles while all carbon super-capacitor batteries have life measured in 100000 cycles). Meaning you would need to change Li-Ion power wall each 5-6 years while super-capacitor all carbon brother would last more than 100 years! Meaning that over 50 years you would need to buy ~10 Li-Ion power walls, costing $80000 while if you pay all carbon will cost you $8000 (if we take the same price, but we believe that all carbon battery can be made considerably cheaper)

Materials - price of batteries depends highly on other materials used in manufacturing.
For instance typical Li-Ion battery cells has steel, nickel, lithium, carbon, polyethylene foils etc.
Cell containers for instance (nickel plated A3 steel) weighing 9.3 g per cell. Tesla’s 85kWh car battery weights in total 540 kg — just those cell containers have weight of 67 kg (almost 13% of total weight). Different type of chemistries can utilise much lighter containers significantly reducing cost.

Production – fewer materials mean fewer manufacturing steps, which translate to more savings during manufacturing process and therefore lowering overall cost of the production.

Please read Carbon Sequestration by Leaves - Part 2 for more information.