Arbor Energy, an American climate tech company founded in 2022, develops a modular, compact system that converts biomass into carbon-negative electricity and clean water, while also permanently removing CO₂ from the atmosphere via a process known as Biomass Carbon Removal and Storage (BiCRS). Arbor’s modular and compact carbon removal system has an inherent carbon capture efficiency of nearly 100%, making it a promising method for reversing humanity’s climate footprint.
Challenges: carbon emissions and BiCRS
Carbon emissions
Since the early 1900s, carbon dioxide (CO₂) levels in the atmosphere have increased by 50% due to human activities. When fossil fuels (such as coal, oil, and natural gas) are burned for energy production, transportation, and industrial processes, CO₂ is released into the atmosphere. This excess CO₂ acts as a greenhouse gas, trapping heat and causing the air and ocean temperatures to rise. CO₂ emissions play a crucial role in driving climate change.
This warming effect has caused the global average temperature to rise by about 1.1 ºC since the pre-industrial period. This has led to rising in the frequency and intensity of extreme weather events, melting of polar ice caps and glaciers and rising sea levels, shifts in species ranges and increased risk of species extinction, agriculture and food security, and ocean acidification.
To mitigate these impacts, the Paris Agreement aims to limit global warming to well below 2 ºC above pre-industrial levels. The Intergovernmental Panel on Climate Change (IPCC) estimates that a “carbon budget” of about 500 GtCO₂, which corresponds to about ten years at current emission rates, provides a 66% chance of limiting global warming to 1.5 ºC.
Biomass Carbon Removal and Storage (BiCRS)
Biomass Carbon Removal and Storage (BiCRS) is different from Direct Air Capture (DAC) technology in that it lets plants do the hard work of scrubbing CO₂ out of the atmosphere through photosynthesis. It turns biomass into biochar or CO₂ that can be sequestered permanently, thereby removing CO₂ from the air.
One example of BiCRS technology is Bioenergy with Carbon Capture and Storage (BECCS). During BECCS, biomass is converted into bioenergy while carbon is captured and stored. The carbon in the biomass comes from CO₂ taken from the air during photosynthesis. Biomass is processed via combustion, pyrolysis, or other conversion methods. During the process, energy is extracted in useful forms of electricity, heat, etc., and CO₂ or biochar produced can be sequestered geologically or disposed of in landfills, respectively.
Arbor Energy Technology
Arbor Energy (Arbor) has developed a modular, compact system that combines the technologies of torrefaction, oxy-gasification, oxy-combustion, and supercritical CO₂ power cycles to efficiently convert biomass to a stream of high-purity, supercritical CO₂. The supercritical CO₂ stream can be directly injected into class VI wells, resulting in the permanent carbon sequestration. Carbon-negative electricity and clean water are also produced during the processes. Electricity generated can be used to power the facilities, and any surplus can be sold back to the grid.
Arbor system
The diagram below depicts the Arbor system for Biomass Carbon Removal and Storage (BiCRS).
In a torrefaction reactor, biomass is dehydrated and transformed into bio-carbon at a low temperature. The bio-carbon produced is then subjected to a gasification process, yielding slag and syngas. The combustion of syngas with pure oxygen produces clean water and ultrapure, supercritical CO₂. This CO₂ stream is then run through a highly dense turbine to generate carbon-negative electricity. The supercritical CO₂ can be directly injected into class VI wells for permanent carbon sequestration.
- Biomass feedstock
Arbor’s system can use a variety of biomass feedstocks, such as forestry waste and agricultural waste, on a planetary scale, allowing for the removal of 5-10 billion tons of CO₂ from the atmosphere.
- Torrefaction
Torrefaction transforms biomass into a solid, carbon-rich material called bio-carbon at temperatures between 200 and 320 ºC.
During the torrefaction, the biomass undergoes chemical decomposition: hemicellulose fibers in the biomass are depolymerized and some volatile organic compounds are being volatilized. The resulting porous bio-carbon has an increased energy density and improved fuel quality for the subsequent gasification process. Also, bio-carbon has improved grindability and better handling and storage properties.
- Gasification
Gasification converts bio-carbon into syngas (synthesis gas), which primarily contains carbon monoxide (CO), hydrogen (H₂), and CO₂.
Bio-carbon is heated in a gasifier at high temperatures (>700 ºC) in a controlled environment with limited oxygen. This prevents combustion and promotes the production of syngas. The syngas produced is used in the subsequent oxy-combustion process. Any impurities or ash fall out of the gasifier as slag during this step. The slag can be used as a construction material and a soil fertilizer.
- Oxy-combustion
Oxy-combustion involves burning syngas in nearly pure oxygen to produce a high-temperature, high-pressure stream of supercritical CO₂. The produced supercritical CO₂ can be used in the supercritical CO₂ power cycle to generate electricity.
During the process, syngas is burned with nearly pure oxygen to produce a high-temperature, high-pressure stream of supercritical CO₂ (sCO₂) and water vapor. Using a series of heat exchangers and separators, the sCO₂ is separated from the water vapor for the sCO₂ power cycle to generate carbon-negative power.
Using oxy-combustion permits high thermal efficiency, compact equipment, and reduced water usage. Small equipment can be built in-house, in a modular fashion, and shipped to the sites easily.
- Supercritical CO₂ power cycle
The supercritical CO₂ (sCO₂) power cycle generates energy by utilizing the properties of sCO₂ as the working fluid in a Brayton cycle.
During the process, sCO₂ is heated using a heat source from the oxy-combustion. The transfer of heat to sCO₂ further increases its temperature and pressure. The high-pressure, high-temperature sCO₂ is expanded through a highly-efficient turbine (not disclosed), converting the thermal energy into mechanical energy. The mechanical energy from the turbine is used to drive a generator, which converts the rotational motion into electrical energy. After passing through the turbine, sCO₂ is cooled. The cooled sCO₂ is then returned to the beginning of the cycle to repeat the process.
The sCO₂ power cycle offers higher efficiency, compact equipment, and reduced water usage. According to Arbor, its power system has the highest power density of any machine on Earth.
- Carbon Capture and Storage
High-purity sCO₂ can be injected into class VI wells for permanent sequestration, effectively removing it from the atmosphere.
Arbor Energy Products
Market of Biomass Carbon Removal and Storage
The Biomass Carbon Removal and Storage (BiCRS) market is a niche segment of the carbon capture, utilization, and storage (CCUS) market. The CCUS global market was valued at approximately $2.1 billion in 2020. It is expected to reach $4.25 billion by 2025, growing at a compound annual growth rate (CAGR) of 15.2%. This growth is driven by increasing awareness of climate change, supportive government policies, technological advancements, and industry collaboration.
The majority of the CCUS market is currently focused on carbon capture technologies for fossil fuel-based power plants and industrial processes. However, the interest in BiCRS is growing due to its potential to remove CO₂ directly from the atmosphere and store it in a more sustainable manner. As the technology matures and gains wider acceptance, the BiCRS market is expected to experience significant growth in the coming years.
Arbor Energy product
By 2025, Arbor will have a demonstration plant for BiCRS in Ophir, CA. The demonstration plant is able to process 30,000 tons of forest waste annually, removing 50,000 tons CO₂. 2-3 MW of carbon-negative electricity can be generated. The byproducts are 3 million gallons of pure water per year and 250 tons of slag per year.
Arbor will collaborate with CTI Energy to inject CO₂ into Class VI wells for permanent CO₂ sequestration.
Arbor Energy Funding
Arbor Energy has raised a total of $12.5M in funding over 1 round. This was a Seed round raised on Jan 1, 2022.
Arbor Energy Investors
Arbor Energy is funded by 4 investors, including
Arbor Energy Founder
Brad Hartwig is Founder.
Arbor Energy CEO
Brad Hartwig is CEO.
