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Comment by torpfactory | Hacker News Reader

Wood pellet burning is a temporary distraction and distortion caused by regulation that allows it to be counted as "renewable". I believe you can make a reasonable argument wood burning is carbon neutral. Unfortunately, land used for growing forests of fuel represents a terrible opportunity cost - you could grow food or let the forests absorb atmospheric carbon, provide animal habitat, re-wilding, etc.

However, there is no long-term future in which wood pellets are used for much other than limited residential space heating. Cutting down a forest, processing it into pellets and shipping them half way around the world isn't going to be the cheapest option for bulk power production.

Don't let the foolishness of wood-burning being counted as "renewable" distract you from the broader story of the quickly improving value proposition of solar, wind, and (soon, hopefully) battery storage.

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I'm not sure you can make a reasonable argument that burning wood is carbon neutral, unless you want to open the door to saying that any CO2 emission is carbon neutral because the carbon can be reclaimed when it is converted into plant matter. It is kind of an absurd argument, unfalsifiable because it also applies to kerogen-based fuels like petroleum and natural gas, both of which begin their long life cycles as organic matter.

Burning wood to generate energy puts more CO2 into the atmosphere than burning fossil fuels to create the same amount of energy, because wood has a lower energy density. Under ideal conditions, most of that CO2 can eventually be reclaimed, if the forest is allowed to regrow. That takes decades, however, during which atmospheric CO2 is higher than it would be otherwise. This creates harms from climate change, including some that are irreversible, like ice-sheet melt and permafrost thaw. But emissions from burning wood are only partially reclaimed by forest regrowth, because:

- harvesting trees results in release of CO2 from soils, which continues for decades;

- burning natural hardwood forest and replacing with fast-growing forest plantations (a common practice), permanently elevates atmospheric CO2 because plantations don’t store as much carbon as natural forests;

- cutting and processing wood uses energy, which generally results in CO2 emissions.

https://whrc.org/burning-wood-for-energy-is-not-carbon-neutr...

(note, not defending Biomass)

While Biomass should not be treated as 'renewable', the key difference between burning biomass versus coal is that the inherent carbon in biomass could be treated as a cycling of carbon that already exists in the carbon cycle (assuming where it is harvested is then replanted with trees, which many of them are) - versus the burning of coal (or any other fossil fuel) which takes 'stored carbon in the ground' that has NOT been part of the carbon cycle for millions of years and increases the total amount of carbon in the atmosphere & the overall 'natural carbon cycle'.

So - 'in the fullness of time' (decades) it is 'carbon neutral'.

But the tragedy in Biomass is not just the destruction of forests as you mention (sometimes old growth) or the loss of an active carbon sink - the carbon dioxide is still released and will be sitting around when we least need it to - it will still warm the planet.

Hopefully, the EU and other countries will abandon the Biomass retrofits and jump ahead to accelerated Solar, Wind and Energy Storage deployments.

>- harvesting trees results in release of CO2 from soils, which continues for decades;

I coppice, no tree dies, the soil is not disrupted.

>- burning natural hardwood forest and replacing with fast-growing forest plantations (a common practice), permanently elevates atmospheric CO2 because plantations don’t store as much carbon as natural forests;

There are plenty of fast growing woods - willow, beech, hazel

>- cutting and processing wood uses energy, which generally results in CO2 emissions.

Meaculpa - I use a chainsaw, but there is a future in which I can use an electric saw and and axe (I use an axe alot now anyway)

Wood pellets are at least a useful transitional resource. I'm not sure how pellets compare as a coal replacement, but for residential heating a pellet stove is a big improvement over a split log fireplace or stove, in efficiency and air quality.

Do we have carbon neutral batteries yet? Last I saw the production chain for lithium-ion was not carbon neutral over the expected lifetime of the product but rather increased carbon emissions. I’m having a hard time finding numbers to compare with wood pellets or coal, though, so I’m curious if you know.

How could a battery be carbon-neutral? What does that even mean? A batter doesn't produce energy, how could it be carbon-neutral by itself?

Batteries are good for N cycles (to simplify) and take M carbon to produce. If it cycles N times and is charged with fuel that emits <M carbon, that’s going to be a net carbon output surplus. This is expected and desired from solar to have some carbon output as a tradeoff to supply bursts of demand, but needs to be compared with eg a comparable coal plant (or “wood pellet” plant I guess) in order to figure out how much improvement it gives.

In a grid context the battery produces energy, specifically in that it allows other renewable producers to produce more.

You can't make an argument that it's carbon neutral -- They don't just burn deadfall, and you can't grow trees faster than you can burn them.

Prior to coal, the developed world burned massive amounts of wood, which contributed to massive deforestation. This is literally a step backwards, and not in any good way. When civilization burned wood for energy >500 years ago, sure, because demand was so low. But by the 1700-1800's demand for energy was so high that burning wood was untenable - coal literally saved the forests. Today, energy demands are exponentially higher, and there's no chance biomass is going to be better than coal from an impact standpoint.

I hate to disagree on renewables, but I think there is also no way renewables as we think of them today (wind, solar, batteries) are going to be the answer either. At best they are a tool enabling independence from grids, but from a worldwide energy demand perspective, they are untenable. I think Michael Moore's recent film did a decent job of outlining the problem. Next gen nuclear is probably our only hope save population reduction (hello COVID).

That Michael Moore film is pretty terrible and doesn't contain the best available and most recent science. I wouldn't consider it a reliable source.

I explained in another comment that Michael Moore isn't the first, nor most reputable, to make these points. He's the first to expose the casual consumer to the problem set.

"pretty terrible" and "best available and most recent science" are squirrelly evaluations. To be specific, you're alluding to the idea that the most recent technology improves the efficiency of solar panels and may extend their lifespan, but these marginal improvements in efficiency and lifespan aren't enough to cast aside the incredible costs in strip mining (ecosystem destruction and fossil fuel energy use), manufacturing (energy use), transportation (energy use), installation(energy use and further processed materials), and operations/maintenance (energy use, e-waste). I mean, that's a quantifiable cost to balance against quantifiable (and intermittent) output and the numbers don't bode well for renewables scaling up/out and truly denting fossil fuel consumption.

The core problem is worldwide energy demand is climbing higher and faster than renewables will ever be able to address. For the fractional role they play, the payout of renewables is undercut by the fact that fossil fuels are used to produce and emplace renewable infrastructure, renewable infrastructure (at a facility level) has an enormous environmental footprint (read: habitat destruction), and has to be replaced in a few decades at best. They are producing energy maybe 50% of that time, and despite the improvements in storage tech (which has its own environmental issues), you still need to back up the renewables facilities with.. fossil fuels.

All this is to say that we need to be looking at other sources (e.g. safe nuclear) to displace fossil fuel.

> you can't grow trees faster than you can burn them.

This is probably true for the UK (large population, not a lot of forest or areas to plant forest).

For e.g. Canada or Sweden it would seem possible. Sweden has 25k square meters (2.5 hectares, or 5 football fields) forest peer person. 85M cubic meters per year is cut down which is around 2% and roughly the same area planted (8.5cubic meters per person). The energy content of it is 150-200Twh which is comparable to Sweden’s energy consumption of 350Twh/year.

Obviously as little as possible is really used for energy because the value in wood for other products (timber, paper) is higher, but at least it shows that the forest as a source of energy is viable and largely sustainable. All that’s needed is a huge country full of mostly forest. Places that don’t have ten thousand trees per head to begin with can’t do this obviously, and countries that do have trees will much rather sell toilet paper and bookshelves to the UK than burn pellets.

Mass reforestation is possible in a generation or two though... In Lithuania for example a lot of reforestation was done in the later half of the last century, the percentage of the land that is forested now is 33% compared to 20% in the 40s.

http://www.china-ceecforestry.org/wp-content/uploads/2017/01...

Or a carbon sink.

Most of these trees are coming from temperate forests, and while tropical forests don't put much carbon in the soil, temperate forests do. Or rather, mature trees in temperate forests do.

As long as you can keep the temperate zones from moving too far toward the poles (and plant tundra aggressively as it thaws) that's another opportunity cost of cutting them down before they hit their stride.

In Sweden, our agencies classify pellets as better than fossil fuels, but with problematic local effects, and it's estimated that each year 1 in 10000 die from its pollution. (1000 people in Sweden, in a population of 10 million.)

One can assume that locally the effects must be worse?

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