Doctor of Philosophy / Department of Agricultural Economics / Jeffery R. Williams / Over the last few decades there has been a shift in electricity production in the U.S. Renewable energy sources are becoming more widely used. In addition, electric generation plants that use coal inputs are more heavily regulated than a couple decades ago. This shift in electricity production was brought on by changes in federal policy – a desire for electricity produced in the U.S. which led to policies being adopted that encourage the use of renewable energy. The change in production practices due to policies may have led to changes in the productivity of electric generation plants. Multiple studies have examined the most efficient electric generation plants using the data envelopment analysis (DEA) approach. This study builds on past research to answer three questions: 1) Does the level of aggregation of fuel input variables affect the plant efficiency scores and how does the efficiency of renewable energy input compare to nonrenewable energy inputs; 2) Are policies geared toward directly or indirectly reducing greenhouse gas emissions affecting the production efficiencies of greenhouse gas emitting electric generation plants; and 3) Do renewable energy policies and the use of intermittent energy sources (i.e. wind and solar) affect the productivity growth of electric generation plants. All three analysis, presented in three essays, use U.S. plant level data obtained from the Energy Information Administration to answer these questions. The first two essays use DEA to determine the pure technical, overall technical, and scale efficiencies of electric generation plants. The third essay uses DEA within the Malmquist index to assess the change in productivity over time. Results indicate that the level of aggregation does matter particularly for scale efficiency. This implies that valuable information is likely lost when fuel inputs are aggregated together. Policies directly focused on reducing greenhouse gas emissions may improve the production efficiencies of greenhouse gas emitting electric generation plants. However, renewable energy policies do not have an effect on productivity growth. Renewable energy inputs are found to be as efficient if not more efficient than traditional energy sources.

The ongoing energy transition in Germany foresees significant increases in the share of renewable energies in the country’s electricity mix until 2030. A share of 80% is targeted and photovoltaics should have a major contribution with a total capacity of 215 Gigawatts aimed to be installed. Since the beginning of the energy transition in Germany, the Renewable Energy Sources Act (EEG) has played a key role with its regulations and support measures. The latest amendment of the EEG in January 2023 includes updated capacity addition targets and regulatory measures. In recent years, the solar branch in Germany has experienced growth after a period of drought from 2013 to 2017. The governmental plans are the basis to enable further growth, but challenges and uncertainties remain if the targets can be reached under the present and anticipated future constraints. This paper presents an evaluation of the feasibility of the capacity addition targets for photovoltaics and outlines the potential contribution of different photovoltaics system types within the installation plans. Through the conduction of semi-structured interviews with different stakeholders of the solar branch in Germany, a large variety of knowledge, experiences, perspectives and assessments is combined to theory which provides answers to the research questions. The results of the data analyses show, that the governmental targets are theoretically feasible but it is doubtful whether they will be reached in practice. Two of the main challenges which will need to be overcome are lacking installation capacities in form of skilled workers and hindering bureaucratic processes regarding planning, approvals, operations and accounting of photovoltaics plants. Moreover, the results indicate that the share of large-scale systems should increase, as scale-effects make them more cost-efficient and more capacity can be installed in the same amount of time. Most of these systems will be ground-mounted, but industrial roof-top systems will also contribute to a certain extent. Furthermore, integrated photovoltaic applications will increase in importance, due to the scarcity of areas and potential synergies. However, most of the stakeholders do not see a major contribution of such systems until 2030, as costs are too high, specific regulations are missing and market awareness is still low. Despite the dominance of large-scale systems, the segment of residential roof-top photovoltaic systems also has a high potential and consumers will want to produce their own electricity due to high energy prices and supply uncertainties.

This thesis focuses on the renewable energy policies for the case study countries (European Union, United States, United Kingdom, Turkey, and Nigeria) with using quantitative and qualitative analysis. The thesis adopts a three -pronged approach to address three main issues: The first paper investigates a 1990-2008 panel dataset to conduct an econometric analysis of policy instruments, such as; feed-in tariffs, quotas, tenders, and tax incentives, in promoting renewable energy deployment in 27 EU countries and 50 US states. The results suggest that renewable energy policy instruments play a significant role in encouraging renewable energy sources. Using data from 1990 to 2012 with the vector auto regression (VAR) approach for three case study countries, namely United Kingdom, Turkey, and Nigeria, the second paper focuses on how renewable energy consumption as part of total electricity consumption is affected by economic growth and electricity prices. The findings from the VAR model illustrate that the relationship between case study countries’ economic growth and renewable energy consumption is positive and economic growth in case study countries respond positively and significantly. The third paper focuses on the relationship between renewable energy policies and investment in renewables in the countries of United Kingdom and Turkey. The third paper builds upon current knowledge of renewable energy investment and develops a new conceptual framework to guide analyses of policies to support renewables. Past and current trends in the field of renewable energy investment are investigated by reviewing the literature on renewable energy investment linkage with policies, which identifies patterns and similarities in RE investment. This also includes the interview analysis with investors focusing on policies for renewable energy investment. The results from the interview and conceptual analysis show that renewable policies play a crucial role in determining investment in renewable energy sources. The findings from this thesis demonstrate that renewable energy policies increase with a growth of the renewable energy investment in the sector. Finally, the outcomes of this thesis also contribute to the energy economics literature, especially for academic and subsequent research purposes.

Renewable energy is a current issue in the world as well as in Turkey. Turkey has developing policies in the renewable energy field. Although it is a beneficial mean of obtaining energy, there are barriers on renewable energy production. In order to develop renewable energies, those barriers have to be analyzed and suitable implementations should be developed to overcome them. In this thesis policy and implementation on the renewables are evaluated in general and specially for Turkey. The electricity market is one of the crucial factors of development of the renewable energy. The day-ahead market and renewable energy support mechanism in Turkey are investigated. Finally benefit calculations is carried out in order to compare benefits of renewable energy in market and support mechanisms by using real time price and production values of two renewable energy plants / a hydropower and a wind power plants. Further, outcomes of newly developed prediction project for wind power plants are evaluated in terms of market benefit.