Simple, cost-efficient solvents reduce CO₂, offer efficient and economic conversion alternatives

Current atmospheric concentrations of carbon dioxide (CO₂) have exceeded pre-industrial revolution levels by 47 percent. Reducing emissions is key to reducing the climate impacts. In the drive toward decarbonization, Pacific Northwest National Laboratory (PNNL) offers technology that can both capture and convert pre- and post-combustion carbon from industrial plants, turning it into alternative and usable products, such as methane or methanol, and even CO₂ negative building materials.

Conventionally, plant operators can capture CO₂ by using special solvents that treat flue gas before it’s emitted from plant chimneys. But these traditional solvents have a relatively high level of water, making methane conversion difficult. PNNL-developed technology reduces the energy needed to fuel this type of reaction, thanks to easily dissolvable solvents that require less pressure to run the conversion.

Traditionally, CO₂ is stripped from water-rich solvents and sent off-site to be converted or stored underground. Under a new, PNNL-developed method, captured CO₂ can be mixed with renewable hydrogen and a catalyst in a simple chamber, then heated at half the pressure used in conventional methods to make methane. The reaction is efficient and converts more than 90 percent of captured CO₂ to methane. Plus, PNNL technology captures more than 95 percent of CO₂ emitted in flue gas.

Turning CO₂ into fuels and more

In recent years, there has been increased demand for methanol, which has even more applications than methane. It can be used as a base for different types of fuel, including marine fuel and biodiesel, and it has historically been used in the chemical industry to produce a variety of products, such as formaldehyde or silicone. Traditionally, methanol has been derived from non-renewable fossil fuels. PNNL has developed technology to produce methanol from renewable hydrogen and captured CO₂ for less than $2.05 per gallon.

Ultimately, each conversion product is developed through two distinctive technologies: carbon capture via PNNL’s solvent technology and the catalytic hydrogenation of CO₂ to methanol in the same solvent.

PNNL-developed solvents snatch waste CO₂ from power plant flue gas, binding the greenhouse gas so it can then be converted into useful products. 

An added benefit of the carbon capture technology is that PNNL’s technology skips steps that standard processes typically require, making the overall integrated process less energy intensive. It minimizes cost by bypassing the compression and shipping of CO₂ that normally occurs in most standard processes. Since the CO₂ is converted to valuable chemicals directly within the solvent, there is no need for separate mechanical compression of the CO₂ prior to being reacted upon because it’s already been condensed in the carbon capture solvent.  

The process is enabled by the enhanced reactivity of CO₂ chemically complexed to PNNL’s single-component solvents, opening new, more efficient routes to make chemicals like methanol or methane from captured CO₂.

PNNL’s capture and conversion technology could be used in modular, distributed-scale processing platforms, which can enable a variety of use cases, including landfill gas treatment, waste-water treatment plants, and manure or farming-related off-gas.