© 2021, The Author(s).Dikili-Izmir Region (Western Turkey) has been an active area of development for the utilization of geothermal resources. In this study, we aim to quantify the untapped resource-potential in this region for both direct and indirect utilization purposes. After collecting geological data from the literature, probabilistic heat-in-place calculations are carried out. Yuntdağ Volcanites and Kozak Pluton are considered, and the latter is proposed as an enhanced geothermal system. It is shown that, with 50% probability, 75 MWe and 17 MWe of net electrical power can be produced from Yuntdağ and Kozak reservoir systems, respectively. When the unit volumes of reservoirs are considered, Kozak can produce 3.2 and 2.5 times of what Yuntdağ can produce in terms of electrical and thermal power, respectively. A sensitivity analysis is performed to understand the impact of reservoir characteristics on the reserves. Within the uncertainty ranges defined, reservoir size, temperature and recovery factor are found to be critical parameters that affect the net power output. Sustainability attributes are evaluated from both economic and environmental perspectives and potential benefits are discussed.