The two main types of technology that can mitigate climate change are emissions reduction technologies (which prevent greenhouse gases from entering the atmosphere) and carbon removal technologies (which pull greenhouse gases back out of the atmosphere after they’ve been released). These two categories work from opposite directions toward the same goal: lowering the total concentration of heat-trapping gases surrounding the planet.
Emissions Reduction Technologies
The first and most impactful category focuses on replacing the fossil fuels that produce carbon dioxide in the first place. This includes renewable energy sources like solar panels and wind turbines, as well as nuclear power. The logic is straightforward: if you generate electricity without burning coal, oil, or natural gas, you eliminate the emissions at the source.
Solar and wind power have become remarkably cost-competitive. According to the U.S. Energy Information Administration, new onshore wind facilities entering service in 2030 are projected to produce electricity at about $30 per megawatt-hour, while utility-scale solar comes in around $38 per megawatt-hour. Natural gas, long considered the cheapest option, sits higher at roughly $59 per megawatt-hour. The economic case for renewables has essentially flipped in the last decade.
The challenge with solar and wind is that they only generate power when the sun shines or the wind blows. Grid-scale battery storage addresses this gap by saving excess energy for later use. By 2022, the U.S. had deployed battery systems with a combined capacity of about 8,842 megawatts of power and 11,105 megawatt-hours of stored energy, and that number has been growing rapidly since 2014. As storage improves, renewables become viable as round-the-clock power sources rather than supplements to fossil fuel plants.
Nuclear energy fits this category too. Nuclear plants produce zero carbon emissions during operation and can run continuously regardless of weather. They’re expensive and slow to build, but they provide a stable baseline of clean power that complements the variable output of wind and solar.
Carbon Removal Technologies
The second category takes a fundamentally different approach. Instead of preventing new emissions, these technologies actively remove carbon dioxide that’s already in the atmosphere. The Intergovernmental Panel on Climate Change calls these “negative emissions technologies” because they reduce the total amount of CO2 in the air rather than just slowing how fast it accumulates.
Direct air capture (DAC) is the most engineered version of this concept. DAC plants use chemical processes to filter carbon dioxide directly from ambient air, then either store it underground permanently or use it in industrial products. The technology works, but it’s still in its infancy. According to the International Energy Agency, only 27 DAC plants have been commissioned worldwide, and together they capture less than 10,000 tons of CO2 per year. Just three plants capture 1,000 tons or more annually: the Climeworks Orca facility in Iceland, a Global Thermostat plant in Colorado, and Heirloom’s facility in California.
For perspective, global CO2 emissions exceed 35 billion tons per year. Current DAC capacity covers a vanishingly small fraction of that, which is why the technology needs massive scaling before it can make a meaningful dent.
Other carbon removal approaches are less mechanical but still important. Reforestation uses trees as natural carbon sinks, pulling CO2 from the air through photosynthesis. Biochar involves converting plant waste into a charcoal-like substance and burying it in soil, locking carbon away for centuries. Enhanced weathering speeds up a natural process where certain minerals absorb CO2 as they break down, by crushing those minerals and spreading them across farmland. Ocean fertilization stimulates the growth of carbon-absorbing algae by adding nutrients to seawater, though this approach remains controversial and poorly understood.
Why Both Categories Are Necessary
Emissions reduction alone can’t solve the problem. Even if the world switched entirely to clean energy tomorrow, centuries of accumulated CO2 would continue warming the planet. Carbon removal technologies are needed to address that existing stockpile. At the same time, carbon removal can’t keep pace if emissions continue at current levels. Removing 10,000 tons per year while emitting 35 billion is like bailing out a sinking ship with a teaspoon.
The UN Environment Programme has estimated that the gap between current emissions trajectories and what’s needed to limit warming to 1.5°C could be as large as 16 to 19 gigatons of CO2 equivalent per year. Closing a gap that size requires aggressive deployment of both technology types simultaneously.
Cost and Scaling Challenges
Renewable energy has already crossed the threshold into economic viability. Solar and wind are now cheaper to build than new fossil fuel plants in most markets, and costs continue to fall. The remaining barriers are largely about infrastructure: building enough transmission lines, deploying enough battery storage, and modernizing electrical grids designed for centralized power plants.
Carbon removal faces steeper obstacles. Building carbon capture systems onto existing power plants costs roughly $1.7 million per megawatt of capacity for a first-of-a-kind facility, according to the U.S. Department of Energy. That cost is expected to drop by about 25% as the technology matures and construction becomes standardized, bringing it closer to $1.3 million per megawatt. Operating costs are also projected to decrease by around 10% as systems become more efficient. Still, these are enormous investments, and the economics only work with strong policy incentives or a meaningful price on carbon emissions.
The two technology categories are at very different stages of maturity. Renewable energy is a proven, market-competitive industry deploying at massive scale. Carbon removal is largely experimental, with a handful of small facilities demonstrating the concept while researchers work to bring costs down. Both are essential pieces of the climate puzzle, but they require different kinds of support: renewables need infrastructure investment and grid modernization, while carbon removal needs research funding, pilot projects, and policies that create demand for captured carbon.