Methane recovery

The initial biogas recovered is an MHV gas and is often upgraded to high heat value (HHV) gas when used for blending with natural gas suppHes. The aimual production of HHV gas ia 1987, produced by 11 HHV gasification facihties, was 116 x 10 m of pipehne-quaUty gas, ie, 0.004 EJ (121). This is an iacrease from the 1980 production of 11.3 X 10 m . Another 38 landfill gas recovery plants produced an estimated 218 x 10 m of MHV gas, ie, 0.005 EJ. Additions to production can be expected because of landfill recovery sites that have been identified as suitable for methane recovery. In 1988, there were 51 sites ia preliminary evaluation and 42 sites were proposed as potential sites (121). 

To estimate the large-scale storage capacity of 45 important coal basins during Enhanced Coal Bed Methane Recovery (ECBM) in China, Li et al. used an equation which can be modified to a simpler form without considering the different coal bed basins [63, 79]. 

PhungQ.H., Kyuro S., et al. Numerical simulation of C02 enhanced coal bed methane recovery for a Vietnamese coal seam. 2010 Journal of Novel Carbon Resource Science 2 1-7. 

Displacing the methane tied up in deep unmineable coal adds another small carbon sink to the portfolio of options and this process is called enhanced coal bed methane recovery. When injected into a coal bed, C02 can replace adsorbed methane. By doing so, coal beds can serve as a C02 reservoir and a source for methane production (Parson and Keith, 1998). This method is attractive in the sense that most of the injected C02 will be immobilized by either physical or chemical adsorption on the coal surface. 

Kryosol An adsorptive process for purifying methane from landfill gas. Operated at high pressure. The overall methane recovery is 90 to 95 percent. 

Comparison of C02-N2-enhanced coalbed methane recovery and CO2 storage for low- high-rank coals, Alberta, Canada and Shanxi, China... 

Figure 2 shows examples of simulation computations of ECBM recovery, which schematically illustrate the methane recovery rate for two enhanced recovery scenarios, the first due to injection of pure N2 and the second due to injection of pure C02. Also illustrated is the expected recovery without injection (primary production). 

Mavor, M.J., Gunter, W.D., Robinson, J.R. 2004. Alberta multi-well micro-pilot testing for CBM properties, enhanced coalbed methane recovery and C02 storage potential. Paper SPE 90256, presented at SPE Annual Technical Conference and Exhibition, Houston, Texas. 

Lusk, P. (1998) Methane recovery from animal manures. The current opportunities casebook. NREL, Golden, Colorado, pp. i-7.3. 

Schumacher, M. M. Landfill Methane Recovery Noyes Data Corporation Park Ridge, NY, 1983. 

It is also of practical interests to control hydrate decomposition. The early studies were intended to understand the mechanism of hydrate decomposition when plugging in pipeline was encountered. The hydrate crystals generally decompose by de-pressurization (Kelkar et al., 1998, Peters et al., 2000 Hong et al., 2006). Thermal stimulation has also been considered in order to provide strategies for methane recovery from the natural hydrate by thermal stimulation (Selim and Sloan, 1989 Ji et al., 2001 Hong et al., 2003 Hong and Pooladi-Darvish, 2005). Hydrate decomposition studies may also be applicable to gas storage in hydrates. 

Enhancementof methane recovery through monitoring ofCOj injected into deep coal beds ... 

Development of Advanced Reservoir Characterisation and Simulation Tools for Improved Coalbed Methane Recovery. Led by Imperial College of Science Technology and Medicine, the main objective of this project is to develop technology and tools to more accurately assess the potential for improved methane recovery and COj sequestration by investigating the basic scientific phenomena of COj coal injection and retention. The researchers primary objective is to achieve a more comprehensive understanding of the fundamental mechanisms of water and CO2-CH4 adsorption/desorption, diffusion/counter diffusion, and 2-phase flow under simulated reservoir conditions (stress, pore pressure, and temperature). The results of these studies will then be applied to design of a CO2-ICBM recovery and COj sequestration simulator for the European industry. 

Gas production is considerably greater from commercial landfill methane recovery systems. In 1987, 94 plants (50 operational, 44 scheduled) had an estimated design production of 1.2 x 106 m3/d and an estimated actual production of 0.314 x 106 m3/d, or 114 x 106 m3/yr estimated electric capacity was 231.2 MW (120-123). 

INCLUDING C02 SEQUESTRATION AND COALBED METHANE RECOVERY ECONOMICS, C02 EMISSIONS, AND ENERGY BALANCE... 

Wyodak coal from Wyoming was selected as a suitable low-rank Western coal for this study. It is inexpensive to produce and is available in an abundant supply. Additionally, the regulations in Wyoming permit the extraction of coalbed methane, making it attractive for C02 sequestration and coalbed methane recovery. Coal would be mined from this region gasified to produce hydrogen then the C02-rich off gas would be injected into unmineable coal beds. 

In order to compare the economics as well as the overall C02 emissions from each schematic studied in this joint venture, a reference case was analyzed. The reference case included only the process steps associated with coal gasification, shift, and hydrogen purification, but none of the steps associated with C02 sequestration or coalbed methane recovery. Three other process schemes were examined in this study and compared to the reference case. Figure 1 depicts simplified process flow diagrams for the reference case and the other three schemes (note the overall heat integration for each scheme is not shown). The top portion of the figure shows the process steps that are the same for each scheme up to hydrogen purification, while the operations inside the dashed boxes represent the steps that differ between the four cases. 

Gasification by-products—CO2 (nsed for enhanced oil and methane recovery, the food indnstry, nrea fertilizer, possible enhanced greenhouse production, proposed geological disposal), S, N2, Ar, Ni, and V. 

Lusk, P. (1994). Methane Recovery from Animal Manures A Current Opportunities Casebook," NREL/TP-421-7577, DE95004003. National Renewable Energy Laboratory, Golden, CO, December. 

---