IV Minsk International Seminar “Heat Pipes, Heat Pumps, Refrigerators” Minsk, Belarus, September 4-7, 2000 A NEW METHOD OF METHANE STORAGE AND TRANSPORTATION L.L. Vasiliev, L.E. Kanonchik, D.A. Mishkinis, M.I. Rabetsky Luikov Heat and Mass Transfer Institute, Minsk, Republic Belarus Abstract Adsorbed natural gas (ANG) storage and transportation technology recently became competitive to compressed natural gas (CNG) technology due to a high energy density capability achievements. New adsorbents such as monolithic carbons and recently compressed active carbon fibers used in non- cylindrical vessels has made possible to store the same capacity of gas as CNG tanks, but at much lower pressure. New types of gas tanks thermal control systems with internal source of energy input, based on heat pipe heat exchangers make it possible to use different sources of energy ( exhausted gases, wasted engine cooling liquids, solar and other types of energy) to stimulate gas desorption at constant rate of gas delivery and constant pressure (temperature) and avoid the drop of temperature in the storage tank due to the enthalpy of desorption. INTRODUCTION To make adsorbed natural gas systems competitive to compressed natural gas (CNG) , gasoline or diesel fuel, the cost of its storage and refueling systems mast be reduced drastically. Application of a physical adsorption phenomena in the solid media is one way to solve this problem. ANG technology based on natural gas adsorption in porous materials at relatively low pressures 3.5-4 MPa is a challenge to the liquid fuel application. Using lower vessel pressures offers two main benefits: it allows a good design flexibility in tank configuration and placement and reduces the cost to compress natural gas to high pressures. ANG systems have also some benefits such as low pressure in non-cylindrical containers, low capital and operating cost of compression and refueling equipment, reduced global warming potential due to the low energy consumption for compression. Environmental protection initiatives of different environmental agencies have led to intensification of research efforts on ozone and global warming safe gas-fired heat pumps technology. Actually the ANG tanks are mostly developed to replace CNG vessels for vehicles, but in the near future some other applications for adsorbent technologies are transparent, such as gas fired solid sorption heat pumps, because they are absolutely benign for the environment, ANG storage systems used as gas holders for peak shaving operations, gas fired drying chambers, ANG big tanks transportation, LP-propane replace systems, emergency fuel, ets. The one of the first experiments with ANG storage systems were performed in Russia [1,2] , in the Institute of rural mineral resources under the professor Dubinin leadership. Two different types of active carbons were used for methane storage at the pressure interval 0.1-100 MPa and room temperatures. Important increasing of the methane adsorption capacity was found with the pressure increasing up to 5-6 MPa. An application of the pulverized active carbon for ANG tanks with 5-10 times increasing of methane storage capacity (P=3.5 Mpa) was discussed in [3]. Actually Ford Motor Company suggest a low pressure ANG storage vessel for vehicles [4-6], which have the gas capacity at 2 MPa the same as a CNG tank at 15 MPa. AGLARG Co., USA has developed a non-cylindrical tank for the low pressure ANG storage in vehicles [7-8]. The most important ANG storage systems are filled with active carbons made from cellulose sources (coconut shells, peach pits) and from non- cellulose polyvinylidenechloride (PVDC). PVDC carbons are also used for composite carbons fabrication. New types of PVDC were developed in the USSR [9] and used for methane adsorption with good capacity for storage. A two-dimensional model was developed [10] to describe the hydrodynamic, heat transfer and adsorption phenomena associated with the adsorptive storage of methane in cylindrical vessels. The problem of non isothermal behavior of the ANG vessels during discharge was analyzed in [11]. Modern ANG storage vessels need to be competitive with CNG, LPG L.L.Vasiliev et.al. 218