| Abstract |
This paper does an exergetic analyses on the different power systems in Leyte Geothermal Production Field (LGPF) to assess its utilization efficiency. The different power systems in LGPF are compared with each other and against other geothermal power systems in the world. The LGPF is designed to generate 700 MWe of electrical energy from its five main power plants and four optimization plants. The main power plants are composed of Upper Mahiao (127 MWe), Tongonan-I (112.5 MWe), Malitbog-South Sambaloran (231 MWe), Mahanagdong-A (120 MWe), and Mahanagdong-B (60 MWe), while the optimization plants are Tongonan-I Topping Cycle (18 MWe), Malitbog Bottoming Cycle (14.7 MWe), Mahanagdong-A (12 MWe), and Mahanagdong-B (6 MWe) Topping Cycle plants. These power plants are supplied by five Fluid Collection and Disposal Systems (FCDS) using a total of 70 production wells and disposing waste brines into 26 re-injection wells. These power plants and FCDS can generally be classified into four power systems, namely: (1) Single FlashûBinary Cycle in Upper Mahiao; (2) Single FlashûConventional with Topping Cycle in Mahanagdong-B; (3) Double FlashûConventional with Bottoming Cycle in Malitbog-South Sambaloran; and (4) Double FlashûConventional with Topping Cycle in Tongonan-I and Mahanagdong-A. In geothermal power systems, the geothermal fluid does not undergo a complete Rankine cycle, unlike in conventional fossil fuel-fired power systems wherein the process fluid completes the cycle. This is primarily because in two-phase reservoirs, the separated brine is re-injected back to the reservoir and the exhaust steam from the turbo-generators is condensed and disposed as condensates. Since exergy is the maximum useful energy obtainable for utilization, efficiency analyses in geothermal power systems are best approximated by an exergetic analyses along the power cycle based on the available exergy of the geothermal fluid. |