This is chapter 6 of my book, A Natural Language, which exposes the environmental narrative as propaganda and puts bottom-up solutions in front of the actual problem.
Put together, the facade of Drax’s carbon negative ambitions is hiding an orgy of virtue signaling, greenwashing, human rights abuses, environmental destruction, and public health issues. Drax will buy carbon offsets as indulgences. Some of these will go towards tree plantations that produce FSC certified wood. The forestry waste will become wood pellets. Drax will burn those to save the planet, even as wood pellet dust damages the health of its employees. This will produce CO2. Oil giants will pump that CO2 underground to extract more oil. Airlines will burn that part of that oil to fly people in net zero flights. Some of the offsets will fund big conservancies that steal lands from tribal peoples to create nature reserves. Nature loving tourists will go there on safari tours. Miners will move in through the backdoor, in the name of producing solar panels. Homeowners will buy those panels to do their part about climate change — as if their good climate conscience was worth subjecting brown people to cancers and drone strikes. Drax will go on to buy their excess green electricity. Charities will ship obsolete solar panels to Africa. In the end, the electronic waste will poison African water supplies.
All this while, Drax will be claiming in the foreground that it is “one of Europe’s lowest carbon utilities.” These inconvenient realities make it tempting to assess what Drax’s carbon emissions actually are. Its reports make masterful use of forestry math, and provide no actual carbon emissions numbers. Climate think tanks and activist groups are circulating numbers based on these reports regardless. Biofuelwatch cites 13 million tons in 2020. That would make Drax the UK’s largest carbon emitter. These estimates are based on the 7.37 million tons of wood pellets that Drax has burnt in 2020. The number invites comparison with the 10.8 million tons of roundwood logged in the UK that year, but this would be missing the forest for the tree: roundwood is green wood without slash, while wood pellets are dried forestry waste.
The logging industry helpfully publishes numbers that we can use to make an apples to apples comparison. Simplifying a bit, when a tree gets felled, around 20% of its weight gets discarded as slash, 5-10% is bark, 10% ends up as slabs and edging waste, 10-15% becomes sawdust, and 50% is lumber. If we assume that bark, slabs, and lumber all find a use, what pellet makers are left with is 20% of slash and 10-15% of sawdust. To keep things simple, we’re going to assume that one third of any harvested tree ends up as wood pellets. Standing trees are about 50% water by weight, while dried pellets are in the whereabouts of 10-20%. If we assume 20% to be generous to Drax, a back of the envelope calculation shows that we can multiply a wood pellet’s weight by 5/3 to get its green weight. A third of a tree gets turned into pellets, so multiplying the wood pellet weight by 5 gets us the standing tree weight.
With this in mind, we can look into how sustainable Drax’s activities really are. The 7.37 million tons of wood pellets that Drax reports would correspond to 36.85 million tons of standing trees. Roundwood is standing trees minus 20% of slash, so 10.8 million tons of roundwood correspond to 13.5 million tons of standing trees. This means that, each year, Drax is burning almost three times the amount of forestry waste that UK loggers produce to generate about 5% of the UK’s electricity. Drax can crow all it wants about its carbon accounting, but this doesn’t seem sustainable.
Computing Drax’s carbon emissions from burning wood pellets is also straightforward. When wood pellets burn, carbon (atomic weight 12) combines with two oxygens (16) to form carbon dioxide (44). Just shy of half of a pellet’s weight is carbon according to research papers on wood pellet combustion. It is safe to assume that Drax’s engineers are competent and getting a full combustion. This means that we can halve the wood pellet weight to get the carbon, and multiply that by 44/12 to get the carbon emissions. 7.37 million tons of wood pellets yields 13.51 million tons of CO2, which is in line with the numbers that get thrown around online.
We’re not done, however, because 13.51 million tons is only one part of the puzzle. The emissions that appear in Drax’s reports (3.135 million tons of CO2 equivalent) are missing, for one. These are not of interest to us because we’d have nothing to compare them with. Coal power stations are not posting the emissions of the mining activities that they depend on, and no one is even trying to pass the emissions tied to policing the Persian Gulf on gas power stations. (If anything, fossil fuel would make biofuels look like a steal if we began to factor in the costs and emissions of the US military industrial complex that secures energy supply lines.) The emissions that we actually want to look into are those that forestry math keeps out of sight. If we ignore forestry math by computing the emissions of burning wood pellets, we might as well also put a number on the biological emissions tied to harvesting the trees, which international carbon accounting rules also silence as land-based emissions. Not all readers will be familiar with the biology, so let’s introduce a few concepts before continuing.
Schematically, plants have three parts. One is the plant before you. Another is the root system beneath your feet. The last and most important is their relationship with their ecosystem. Plants provide food and habitat for other species. Above ground, plants attract beneficials and pests, predators for the latter, and so on up the food chain. Below ground, plants do more of the same with microbiology and other species in the soil food web. These worlds interact. Surface animals like chickens eat worms. Animals leave waste and carcasses around. They eat plants above and below ground. They die and decompose, as do plants and the rest. Nature is full of such interactions. It is a dynamic system that makes sense only as a whole. Photosynthesis is instrumental to this whole, in that it provides (most of) the energy that makes all of this life possible.
How much organic matter each of these parts contains depends on the plant and the density of biological interactions around it. Warm and moist environments like tropical forests tend to have less soil carbon because organic matter decomposes very quickly, and lush biology all around. Colder environments with a short growing season like tundras tend to accumulate far more soil carbon due to the slower decomposition, and lack the photosynthesis to support a lot of biology above ground. Soil carbon includes plant roots, soil biology, and other organic sources of carbon like dead organic matter and humus. Globally, land ecosystems contain about three times more carbon below ground than above. There is ample variation from one ecosystem to the next. Peatlands, for instance, sequester twice as much carbon as all of the planet’s forests combined in around 3% of the planet’s surface. The richer density in soil is tied to the fact that soil ecosystems can evolve in three dimensions. (The same goes for water.)
In natural ecosystems, species interact with others to form a rich and redundant web of interdependencies. A natural forest has an understory of scrubs, vines, herbs, mosses, and other plants beneath the canopy, along with insects, birds, mammals, and other biology above and below ground. The dynamic balance that emerges keeps all species from becoming too dominant. Predators usually catch up with successful species. When not, those species outgrow their food supply and starve. Moreover, biodiverse systems usually have good species redundancy, such that when one beneficial (or food source) gets suppressed or disappears, other species take over and fill a similar role.
Monoculture crop plantations, by contrast, are biological dead zones. They provide an abundant food supply for pests while seldom providing adequate habitat for predators. That makes them an ideal habitat for pests and not much else. This problem is most visible above ground, where plantation operators need to spray poison to keep weeds and pests in check. It is also the case below ground. There are less (and less diverse) plants above ground that provide photosynthesis. This results in less (and less diverse) dead organic matter and soil biodiversity. Activities like tilling and spraying suppress soil life too. So does harvesting. Soil life recovers over time when these activities happen, but it can take a while. It can take decades, in the case of a cleared forest.
With this being said, Drax explains that it sources its wood from what it calls “working forests.” As it describes such forests on its website, these are basically tree plantations where weeds and mature trees get harvested every so often as self-planted saplings take their place. The photograph it uses to illustrate this shows that biodiversity is still low and that standing trees are well spaced, but Drax deserves praise where due. An improvement that springs to mind would be leaving a few old growth trees around to act as mother trees that help seedlings grow faster. Another would be letting some biodiversity in using a mosaic system or an alley cropping system. Even with these caveats, these working forests are much better than the usual plantations that loggers clear every so many decades because of what happens when a tree gets harvested.
Harvesting a tree (or otherwise damaging a tree or another plant) sets off a cascade of events. Dying plants normally release their nutrients to mycorrhizal fungi networks that go on to make them available to other plants. A healthy plant will instead produce growth hormones to try to grow new leaves. It can fail to survive for one reason or another, such as too much shade or no more nutrient resources. The plant lets go of excess roots either way, because it is no longer photosynthesizing enough sugar to support them all. Decomposers get to work, and the nutrients and growth hormones in dead roots become available for use by other plants. Such is why thinning a tree plantation, or pruning or suppressing plants, promotes growth in nearby plants.
Decomposers play a critical role in the nutrient cycle and the food chain. Bacteria and fungi unlock and recycle nutrients in dead organic matter by breaking it down. They also unlock nutrients in minerals, directly with enzymes or indirectly because of waste that results in redox reactions. They form all sorts of mutually beneficial relationships with plants and animals. Mycorrhizal fungi, in particular, colonize plant roots and form networks of plants connected to one another. This allows the fungi to trade nutrients with plants in exchange for sugars. It also allows plants to exchange resources and signals with one another, like when a tree feeds its nearby offspring, helps a plant so it shades an area that is too hot or too dry, or warns its peers about incoming pests. Trees are communicators. Predators latch onto plants in a food web that extends to the very top of the food chain. Predators play a critical role in soil nutrient availability in that they circulate them as they move, disturb soil, produce waste, and so forth.
The influx of death that follows a tree’s harvest gives rise to all sorts of imbalances in the soil food web. Weak and stressed organisms attract pests and decomposers that feast on dying or dead cells. Decomposers thrive and multiply as they break down this sudden abundance. Like other types of living organisms, microbiology will overextend its food supply in the right conditions. In particular when photosynthesizing plants are harvested above ground. The soil food web is suddenly starved of new sugar inputs. This creates a microbiological boom and bust cycle that is a bit like a mouse swarm: it grows while food is abundant, and cannibalizes itself down to a lower head count when food runs out. Predators like protozoa (basically single-celled animals) and nematodes (roundworms) eventually join in on the binge, as do their own predators up the food chain. They too can outgrow their own food sources. That leads to more dead organic matter, and yet other boom and bust cycles.
This added biological activity increases soil emissions. Soil microbiology generates carbon dioxide, methane, and other greenhouse gasses like nitrous oxides as it breaks down organic and inorganic matter. Plant roots and other underground organisms breathe air in and exhale carbon dioxide. Water evaporates. And so forth. The line between natural soil emissions and man-induced soil emissions is at best fuzzy, and not in the slightest bit neutral. What forestry math does is sweep poor land stewardship practices out of sight. This gives them and the associated soil-related emissions look inevitable, but in reality they are nothing of the sort.
Harvesting a plant, in particular, disturbs the subtle balance that exists between biology above and below ground. The soil food web produces soil respiration while making nutrients available to the ecosystem, and plants above ground soak up carbon dioxide that lingers around them. Harvesting a single plant results in excess soil respiration that surrounding plants will soak up if the carbon dioxide lingers around them for long enough. Clearing a forest or a razing farm field wholesale, by contrast, removes plants that could soak up the excess soil respiration and leaves an area wide open without plants to slow wind down. This basically guarantees that excess soil emissions tied to the harvest will escape into the atmosphere.
These excess soil emissions continue until new plant cover is well established enough to compensate and soak them up. How long this takes depends on light, nutrients, temperature, moisture, what crops are grown and how, and so on. Researchers in different contexts find different results. Some say cleared forests take 25-30 years to become carbon sinks again; others say under 10 years. The specific number matters little to us because we can abstract it away: harvested trees with roots in various stages of decomposition exist, so we can aggregate all emissions together and treat them as a one-off event. Contrary to the externalities that can upset carbon stocks in forestry math, excess soil emissions from past forestry harvests are locked in, so this aggregate is a sensible proxy. The question, then, is how much.
Summary | Next: Climate Fairytales.