The current practice of leaving waste wood in the forest results in the release of CO2 emissions from natural decay or slash burning. This process is considered carbon neutral as the CO2 released is equal to the CO2 captured by the tree. The G4 PCH technology produces a drop-in replacement for fossil natural gas. The conversion of the waste wood to fuel creates value and avoids CO2 emissions associated with fossil fuels.
In order to ensure the highest standards and transparency in calculating the carbon intensity from the production pathways of the RNG process, the following California Environmental Protection Agency's Air Resources Board (ARB) published reports are used (in combination):
The GREET models are designed for transportation fuels, so the G4 biomethane pathway to CNG transportation fuel consists of: 1) collect and transport forest waste to a production plant, 2) produce G4 biomethane, 3) transport/distribute and compress the biomethane for CNG use in vehicles.
The calculated pathway intensity level is 14.4 grams of CO2 equivalent per megajoule. Comparing this to the reported data of 95.86 gCO2e/MJ carbon intensity value for CARBOB gasoline, each producing 10,000 GJ/day Commercial Unit product will displace fossil combustion of 3.3 billion megajoules per annum, which would emit 47,520 total metric tons CO2 per annum. The plant will displace 49.5 billion megajoules of natural gas over its design life, or 712,800 total metric tons CO2. Similar calculations can be generated for the use as a fuel for power generation.
The energy return on energy investment (EROEI) for RNG fuel produced , transported, and distributed to a power plant as a fuel source is calculated at 6.2, where harvest and transport of wood is 87% of the total energy input, the G4 RNG plant is 11%, and fuel transport and distribution is 2%.
Wood waste is transported to the plant in typical regional methods, currently modeled by chipping or hammer milling at the roadside piles and transporting the chips to the production plant by truck. Optional use of the generated methane for the transport trucks is possible.
At the plant, the wood is fed into the process and converted into RNG. The G4 process is pressurized and fully contained. Heat energy for the plant is generated from the wood. Electric power is required for compression and control, which comes from on-site power generated from a steam process. There are no emissions of the methane or other compounds. The plant design will utilize best practice maintenance and operating procedures as standard in all modern process plants to eliminate fugitive emissions. There is no flare in the system design. An atmospheric burner is used to combust wood char derived from the hydro-pyrolysis process; CO2 capture is possible but has not been built into the plant design at this time.
The process does not require the use of water, and there are no liquid waste streams to dispose of. Cooling will be performed with a closed loop system in sensitive areas, even though the cooling requirements are minimized by the extensive use of heat transfer within the plant.
The wood feed contains minerals within its cells, and these components are rejected from the plant as a solid bio ash stream. The ash has been through a heating process and is in an activated form equivalent to the ash after a forest fire. This ash can be used to fertilize and re-nutrient logged areas or any other area.
The biomass collection and transportation jobs may generate new jobs depending on existing location specific practices for forest management. The majority of these jobs will be in forestry areas where traditional forest industry related jobs may be in decline. The G4 technology takes advantage of locally available biomass supply and forest industry workforce, and creates new high value plant operations jobs. In most areas a substantial number of full time jobs will be generated to gather and transport the wood waste to the plant.
In addition to biomass supply and plant operations related jobs, the G4 plants will create and/or support regional based engineering and construction jobs for each new RNG plant. As well, there are addition job opportunities related to project financing and project development, and jobs and funds related to accounting, management, and income and property taxation.