Mote Hydrogen ($1 million to produce carbon-negative hydrogen through biomass gasification)

Mote Hydrogen (Mote), an American cleantech company founded in 2020, develops an energy-efficient biomass gasification system that converts wood biomass waste into high-quality, clean hydrogen. The carbon dioxide by-product is captured and permanently sequestered.

Challenge: biomass energy

Given the pressing issue of climate change, it is imperative to prioritize access to clean and sustainable energy for the development of our global society.

Biomass energy is a type of renewable energy that comes from organic materials. These materials can include things like crop residues, forest residues, special energy crops like switchgrass or willow trees, organic waste from municipalities, and animal waste. Biomass growth has the ability to effectively remove carbon dioxide from the atmosphere, resulting in generally low net carbon emissions. Thus, biomass energy presents a sustainable and potentially carbon-neutral substitute for fossil fuels, providing the additional advantages of waste reduction and economic stimulation for rural regions.

Biomass gasification plays a crucial role in the generation of energy from biomass sources.

Biomass gasification involves a thermochemical process that transforms biomass into a combustible gas mixture known as syngas. This mixture is primarily composed of hydrogen (H₂) and carbon monoxide (CO), with a smaller amount of methane (CH₄) and carbon dioxide (CO₂). This process takes place at elevated temperatures (usually above 700 ºC) with a controlled amount of oxygen and/or steam, but without undergoing complete combustion. Carbon dioxide emitted during the process can be effectively captured and stored for future utilization.

Challenges of biomass gasification

One of the major problems associated with biomass gasification is the efficiency of the gasification process.

The moisture of biomass directly impacts the efficiency of the gasification process. The moisture content of raw biomass is naturally high, (e.g., in some embodiments, 50% water by mass).  High moisture content in biomass requires additional energy to evaporate the water during gasification, which reduces the overall temperature in the gasifier and slows down the endothermic reactions necessary for efficient gasification. This results in lower gasification efficiency and reduced syngas yield.

Moisture in biomass affects the composition and quality of the produced syngas. Higher moisture content can lead to lower concentrations of valuable gasses like hydrogen and carbon monoxide in the syngas, while increasing the production of less desirable components like carbon dioxide.

High moisture content in biomass can lead to the formation of tars and particulates during gasification. These by-products can cause operational issues such as clogging and fouling of equipment, and they require additional cleaning steps to purify the syngas.

Therefore, pre-drying biomass before feeding it into a gasifier has many benefits, including improving gasification efficiency, enhancing syngas quality, reducing tar and particulate emissions, increasing energy efficiency, ensuring operational stability, and lowering transportation and storage costs.

However, utilizing high-grade heat in this manner can be quite expensive, either due to the cost of fuel or the opportunity cost of not using the process heat for other purposes. As a result, the returns on pre-drying biomass may be reduced. When it comes to producing renewable hydrogen, the use of natural gas can have a detrimental impact on the product's environmental profile and may even be strictly prohibited.

Mote Hydrogen Technology

Mote has developed a biomass gasification system that improves the overall efficiency by making use of low-grade waste heat produced within the system for biomass pre-drying. This is accomplished through Mote's innovative approach of combining compressor intercooling with biomass pre-drying. For a gasification plant capacity of 350 short tons of biomass per day on an as-fed basis, approximately 12 GJ/h of heat can be utilized. Thanks to enhanced thermal efficiency, Mote's biomass gasification system offers a higher production rate, decreased electrical demand, and capital savings.

Mote Hydrogen biomass gasification system

The diagram below depicts Mote’s biomass gasification system with an enhanced overall efficiency for hydrogen production.

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