Bringing Europe’s carbon footprint down to zero while keeping the lights on, planes flying, and factories running is a massive challenge, especially without fossil fuels.

That's the puzzle researchers tackled using one of the most detailed energy system models ever built for Europe. What they found challenges the conventional wisdom about biomass—those wood chips, agricultural residues, and organic wastes we've been told to think of primarily as renewable fuel. Turns out, biomass is more valuable as a source of carbon than as a source of energy.

The research team used a sector-coupled optimization model covering electricity, transport, heating, and industry across 37 European nodes. They explored not just the cheapest path to net-zero and net-negative emissions, but thousands of near-optimal alternatives—solutions that cost slightly more but deploy technologies differently.

Their core finding is stark. Excluding biomass entirely from a net-negative emissions scenario (targeting minus 110 percent of 1990 levels) increases total system costs by twenty percent. That's an additional €169 billion annually, roughly matching Europe's combined defense spending. Biomass isn't just helpful. It's load-bearing.

But here's where it gets interesting. The study reveals that biomass matters less for which sector uses it and more for what it does with the carbon inside.

Carbon as Currency

Traditional energy system analyses treated biomass as fuel. Burn it, get heat or power, move on. This research flips that framing.

When biomass burns, it releases biogenic CO₂—carbon recently pulled from the atmosphere by growing plants. Capture that CO₂, and two powerful options emerge. Store it underground, and you create negative emissions, literally pulling yesterday's pollution out of today's air. Use it to make synthetic fuels, and you provide renewable carbon for aviation, shipping, and chemicals—sectors where batteries won't work and hydrogen alone isn't enough.

The researchers found that biomass combined with carbon capture delivers value up to three times higher than biomass used for energy alone. At low biomass availability, that carbon/energy value ratio climbs even higher.

Think of it this way. A ton of wood can generate electricity or heat. But the carbon in that wood—if captured—can do two jobs: offset fossil fuels elsewhere by providing feedstock for jet fuel, or remove CO₂ from the atmosphere permanently. Energy is useful. Carbon is strategic.

This insight reshapes priorities. The model allocated 87 percent of biomass to processes with carbon capture in the cost-optimal scenario. Only when capture rates drop below 75 percent or biomass becomes very expensive does the picture change.

The Flexibility Paradox

Biomass also plays a smaller but crucial role in electricity supply.

The model deployed substantial dispatchable biogas power plants—521 gigawatts of capacity, matching peak inflexible demand. Yet these plants ran only 28 percent of the time. They're insurance, not workhorses. When wind and solar output dips and battery storage empties, biogas fills the gap.

This contrasts with earlier power-system-only studies, which predicted much higher bioelectricity needs. The difference? Sector coupling. Electric vehicles can charge when power is abundant. Electrolyzers can ramp production up and down. Heat pumps can pre-heat buildings before a cold spell. This flexibility dramatically reduces the need for firm generation.

Still, even a small amount of dispatchable bioelectricity proves valuable. Removing it entirely costs more than excluding biomass from any other single sector. Supply reliability matters.

What Goes Where Barely Matters

Perhaps the study's most surprising finding: within a one percent cost increase, biomass allocation is remarkably flexible.

Solid biomass can supply anywhere from zero to 100 percent of medium-temperature industrial heat without significantly affecting total costs. It can cover 20 to 61 percent of liquid fuel demand for aviation and shipping within the same narrow margin. Biomass-fired combined heat and power plants can meet half of district heating needs or none at all.

The reason? Abundant near-optimal solutions. As long as biomass carbon gets captured—enabling negative emissions and fuel feedstock production—the specific pathway matters less than the outcome.

This flexibility extends to regional differences. Local biomass availability, renewable electricity costs, excess heat from hydrogen production, and existing district heating networks all shift what's optimal in each location. Europe likely needs a diversified portfolio of biomass uses, not a one-size-fits-all prescription.

The Alternative: Direct Air Capture

If biomass provides valuable carbon, could we skip it and just grab CO₂ from the air?

Direct air capture (DAC) technology does exactly that, using electricity and heat to extract atmospheric carbon dioxide. The model includes DAC as an option. It rarely gets chosen in cost-optimal scenarios.

The problem isn't just DAC's high capital cost—though that matters. It's that DAC consumes massive amounts of energy to capture dilute CO₂, while biomass processes capture concentrated streams and provide net energy output. Even at optimistic DAC costs, bioenergy with carbon capture remains more competitive across most scenarios.

DAC functions more as a backstop, preventing biomass scarcity from blocking climate targets entirely. If biomass falls short, DAC can fill the gap—at substantial expense.

The Roadblocks

Three major uncertainties shadow these findings.

First, feedstock supply. The study assumes biomass comes from residues—crop leftovers, forestry waste, organic municipal trash. These resources are limited. European policy increasingly restricts food-crop biofuels and primary forest biomass due to sustainability concerns.

Yet model results showing high biomass value could incentivize expanded production beyond residues. Whether that happens sustainably or triggers land-use conflicts depends on governance, not physics.

Second, upstream emissions. Biomass isn't automatically carbon neutral. Extracting forest residues can reduce soil carbon. Importing biomass requires transport. If upstream emissions reach just ten grams of CO₂ per megajoule of biomass, optimal usage patterns shift noticeably. At higher upstream emissions, biomass loses competitiveness unless carbon storage capacity expands to absorb those impacts.

Third, storage limits. The base scenarios tightly constrain carbon sequestration to near what's necessary for meeting targets plus offsetting unavoidable process emissions (like cement production). This forces near-complete decarbonization with minimal fossil fuel use balanced by negative emissions.

Allowing more storage enables using fossil fuels with carbon capture, reducing biomass dependence. But it also demands faster scale-up of geological storage infrastructure—itself uncertain.

What It Takes

Meeting the modeled scenarios requires an unprecedented buildout across multiple technologies.

Wind and solar power must expand to provide 99 percent of electricity generation—nearly triple current levels. Hydrogen electrolysis capacity needs to exceed current global projections. These aren't incremental changes. They're transformation.

If wind or solar deployment lags, the system compensates by demanding more biomass for liquid fuel production. If electrolyzer scale-up falters, again, biomass demand rises. Renewable electricity, hydrogen production, and biomass aren't substitutes in this system—they're complements. Falling short on one strains the others.

The research also highlights a timing challenge. Bioenergy with carbon capture can scale up now using existing biomass and demonstrated capture technologies. Direct air capture needs both cost reductions and stable, massive energy inputs before deployment at meaningful scale. Betting exclusively on future DAC while restricting biomass today increases the risk of missing climate targets.

The Path Not Taken

Energy systems rarely follow cost-optimal paths. Politics, local opposition, industry inertia, and legitimate trade-offs around land use, biodiversity, and equity all shape what actually gets built.

That's why exploring near-optimal solution spaces matters. This study shows that missing the absolute cost minimum by a few percentage points opens wide ranges of technology mixes. Room to maneuver exists.

But that flexibility has limits. Excluding any major category—biomass, wind, solar—drives costs up sharply. And some combinations simply don't work. The model can't achieve targets by cutting both biomass and carbon capture, or by excluding wind and solar together.

The diversity of pathways revealed here offers policymakers options. But it doesn't eliminate hard constraints. Europe can choose how to deploy biomass. It can't easily choose not to deploy it at all.

Credit & Disclaimer: This article is a popular science summary written to make peer-reviewed research accessible to a broad audience. All scientific facts, findings, and conclusions presented here are drawn directly and accurately from the original research paper. Readers are strongly encouraged to consult the full research article for complete data, methodologies, and scientific detail. The article can be accessed through https://doi.org/10.1038/s41560-024-01693-6