The great magnitude of solar-energy flux on the earth has stimulated a number of attempts at its more effective utilization during the last 60 years. Mouchot (1, 2) and Pifre (3, 2) in France, Shuman (4) in Egypt, Ericsson (5), Willsie (6), Shuman (7), and more recently Abbot (8) in America are but a few of the names associated with attempts to prove the economic feasibility of converting solar energy to heat and transferring that heat to the working fluid (steam, air, and sulphur dioxide have been used) of a heat engine. Recently Dr. Godfrey L. Cabot has made possible a continuing research on the problem by establishing an endowment at the Massachusetts Institute of Technology for studying means of more effective utilization of solar energy. Four projects are under way: three in the fields of photochemistry, photoelectricity, and thermoelectricity. The fourth follows the conventional attack on the problem, namely, the collection of solar energy in the form of heat in a fluid and the utilization of that heat. The present paper is a first quantitative report on progress in the last field.

varies from year to year and the amount of water withdrawn, which is the only factor under the control of the users. If the amount of water withdrawn lowers the fresh water head sufficiently, salt water will move up the formation.In the early days of Houston, flowing wells could be obtained almost anywhere within the present city limits, and the artesian head in some wells was sufficient to raise the water from 15 to 30 feet above the ground. Now the artesian head is about 80 feet below the surface in the downtown part of Houston. Between 1920 and 1931 the decline in artesian head averaged about 4 feet a year. Between 1931 and 1936 there was little decline in artesian head in the heavily pumped Houston-Pasadena district. In the area to the south and southeast of Houston, however, the artesian head declined markedly. In 1937 new wells were put down in Pasadena which are reported to have a combined capacity of 20,000,000 gallons a day, an increase of about 40 per cent over the average pumpage for 1931-36. From March, 1937, when these wells were put into operation, to March,. 1938. there was a pronounced decline in water levels in observation wells in the Houston-Pasadena district, particularly in those within 4 miles of the new wells. In two wells, 6/s and ls/4 miles distant, respectively, the decline in water level was 35 feet in the 12-month period. Saky^KaieLjAJam$Ln-iaHie nptffir distant dowmthe dipjnjhe-deeperjjeds, from which a large part of the water in the Houston district is drawn. There is, therefore, a distinct possibility that any large decline in artesian head may result in the encroachment of salty water into the wells of the district. Fortunately such an encroachment is likely to be slow, and can be watched and to a degree anticipated if proper observations are made.The progress report on the ground water resources of the Houston district (3), published in March, 1937, recommends that (a) there should be no increase in pumping igthp.-HnuKtori district, (6) addSlQÜ5rsñüHiés~o7 ground water .should be obtained at a sufficient distance fromlhe clIyAo avoid undue interception oí water_thai 5~repienishing the ground water reservoir in the heavily pumpedJHouston-Pasadena area, and (c) prodigal^ndlrast^SlTiieoI water should be eliminated.

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Bench experiments and laboratory field pilot plant testing have led to the development of a solvent that is selective in removing CO and H S from natural gas at pipeline pressure. The acid gases are physically absorbed in the solvent and no chemical reaction takes place. Introduction A few years ago, most commercial acid-gas removal processes involved the use of either amines or processes involved the use of either amines or potassium carbonate solutions. These materials chemically potassium carbonate solutions. These materials chemically react with hydrogen sulfide and carbon dioxide, giving off appreciable quantities of heat. Heat must be supplied to regenerate the solutions. In recent years, several companies have developed selective solvents to remove acid gases from natural gas and synthesis gas. The selective solvents operate on the principle of pure physical absorption, as one would calculate using vapor-liquid equilibrium ratios (K-values) for the appropriate systems. Since there is a heat of absorption and desorption involved, the heat effects are much smaller than with solutions involving chemical reactions, and the selective solvent can be regenerated without reboiling. Solvent absorption is especially useful in cases where the partial pressure of the acid gas exceeds 150 psia, and preferably 200 psia. The cost advantage of the solvent absorption psia. The cost advantage of the solvent absorption process arises largely from the saving of heat process arises largely from the saving of heat ordinarily used in the regeneration of amines and hot potassium carbonate solutions, which is substantial potassium carbonate solutions, which is substantial when large volumes of acid gas are involved. Preliminary Screening Tests Preliminary Screening Tests Several years ago, we made a detailed study of acid gas processing that led to the discovery of some 11 classes of polar, organic solvents that were effective in removing acid gas. Solubilities of CO and propane were measured in a large number of solvents at 1 atm and about 80 deg. F. Results of these measurements revealed the solvents covered by Union Oil Co. patents. Solubility data related to these solvents and patents. Solubility data related to these solvents and competitive solvents are shown in Table 1. The solubility ratio of CO to propane is a measure of the selectivity of the solvent. A high selectivity is obviously desirable. Some H S solubility data have been included. Table 2 lists properties of these relatively nonvolatile selective solvents. Results from a bench scale pilot plant narrowed the number of solvents of chief interest, and pointed to the need for a field pilot plant for further study. In the fall of 1964, a pilot plant was installed near the Lisbon field, Moab, Utah, to test some of our solvents as well as a competitive solvent on a sour-gas stream; results of the pilot plant tests on methyl cyanoacetate (MCA) and propylene carbonate (PC) are reported here. The pilot plant is still in use to treat fuel gas for gas compressors. Description of Field Pilot Plant The Steams-Roger Corp. of Denver was selected to design and install the field pilot plant, which is shown in Fig. I in a simplified flow diagram. The pilot plant processed up to 1.8 MMcf/D at a pressure of 770 processed up to 1.8 MMcf/D at a pressure of 770 psig during the runs described here. Raw gas psig during the runs described here. Raw gas contained about 30 percent CO and 1 percent H S. Treated gas was obtained with as little as a few tenths of a percent of CO and less than 1/4 grain of H S per 100 scf of gas. The major equipment included in the pilot plant is described below. JPT P. 483