What Drives States to Support Renewable Energy? Steffen Jenner*a,b, Gabriel Chana, Rolf Frankenbergerb, and Mathias Gabelb Why do states support electricity generation from renewable energy sources? Lyon/ Yin (2010), Chandler (2009), and Huang et al. (2007) have answered this question for the adoption of renewable portfolio standards (RPS) at the U.S. state level. This article supplements their work by testing the core hypotheses on the EU27 sample between 1990 and 2010. Furthermore, the article asks why the majority of EU states rely on feed-in-tariffs (FIT). The study conducts logistic time series cross-section regression analyses that run on a hazard model. Evidence in support of private interest theory and public interest theory is provided. (a) The existence of a solar energy association increases the probability of a state to adopt regulation. (b) Solar radiation, and (c) the unemployment rate also increase the odds. (d) Electricity market concentration decreases the probability of transition. Keywords: Energy policy, Renewable energy, Electricity, Feed-in-tariff, Hazard model, Public Choice http://dx.doi.org/10.5547/01956574.33.2.1 1. INTRODUCTION Sky rocketing electricity prices, sky fogging greenhouse gas emissions, looming ‘peak oil’, trade dependencies, emerging economies eating up a rapidly increasing share of global energy demand, and ever depleting global energy supply have put conventional energy sources under pressure. To make things worse, in March 2011, the Japan fallout gave an unexpected blow to nuclear power, a conventional zero-emission power source. * a b Corresponding author: E-Mail: jenner@fas.harvard.edu Harvard University The University of Tübingen. We would like to thank Professor Richard B. Freeman, from Harvard University, for his time and suggestions that substantially improved this article. In addition, we appreciated the helpful comments from two anonymous referees. Remaining errors are ours alone. The Energy Journal, Vol. 33, No. 2. Copyright 䉷 2012 by the IAEE. All rights reserved. 1 2 / The Energy Journal Table 1: Years of Policy Enactment in Europe DE IT DK LU 1990 1992 1993 GR ES AT FR IT PT 1994 1998 2001 BE CZ HU LT GB BG EE NL SE MT SI IE RO SK BG CY 2002 2003 2004 2005 2006 Bold and standard letters indicate a quota system and a feed-in-tariff, respectively. Source: Res-legal (2010) and REN21 (2009). One would expect international alliances, such as the United Nations (UN), to counter challenges that threaten humanity on a global scale. But they struggle in their effort to make agreements binding. It is the state level’s task instead. Even if a club of countries, the European Union (EU) for instance, achieves to negotiate collective targets, e.g. the Directive 2001/77/EC on RESE, the Directive 2003/30/EC on biofuels or the Directive 2009/28/EC on both, the state is urged to do the work on the ground. With conventional power technologies scrutinized or their resources running out, state policymakers promote investment in electricity generation from renewable energy sources (RES-E). As can be reviewed in Table 1 some states, such as Germany and Italy, have been front runners implementing RES-E policies in the early 90th. Others have been more reluctant, to put it mildly. Investigating this gap of enthusiasm, the article supplements similar research on the U.S. states. Answering the question of ‘what drives states to adopt regulation that supports RES-E?’ we run logistic time series cross-section regression analyses. Section two reviews the literature on the puzzle. Section three presents a proportional hazard model. Section four elaborates the variables. Section five lists the findings which are discussed in section six. 2. LITERATURE REVIEW Academia has tackled the question before. Most empirical research applied different types of process tracing to the question why political RES-E support evolved.1 Besides these small-n case studies, a few large-n studies exist as well. Huang et al. (2007) run a logistic model on the U.S. states. They find that Republican party dominance decreases the likelihood of state RES-E support while the educational level of citizens correlates positively. Chandler (2009) specializes in inter-state learning. He finds that neighboring effects exist in U.S. state 1. See Heymann (1998) on wind power in the U.S., Germany and Denmark; Lauber and Mez (2004) on RES-E in Germany; most recently Laird and Stefes (2009)—and Keller´s (2010) response— on the paths of German and U.S. energy policy; and Rabe (2004) on U.S. states’ role in federal climate policy making. Copyright 䉷 2012 by the IAEE. All rights reserved. What Drives States to Support Renewable Energy? / 3 electricity policy. Positive coefficients indicate that RPS systems spread across state borders. Knittel’s (2006) regressions reveal a link between conventional electricity market regulation and strong industrial interests. Lyon and Yin (2010) find significant correlations between private interest as well as party indicators and the odds of RPS adoption. According to their study, the intensity of solar radiation increases the probability of policy adoption while the unemployment rate has a negative impact. Further findings are shown in Table 3 as part of the discussion section. Since none of the quantitative studies we know run their regressions on the EU27 sample, this article contributes to the discourse by testing the common hypotheses on the EU member countries. Choosing the state level for analysis makes sense on both continents. In the U.S., the Obama Administration is only slowly moving forward on introducing federal legislation to support RES-E. In the EU, the European Parliament and the European Commission urge their member countries to foster renewable energy exploitation by setting targets as mentioned above. However, the EU did not employ a policy mechanism to attract investment in electric systems that run on renewable energy sources. To put it in a nutshell, in the U.S. as well as in the EU, RES-E is a matter of state-level legislation (Joskow, 2009). The second contribution lies in extending the pool of policies from RPS to feed-in-tariffs. Prior studies distinguish between states that apply a RPS and the rest of the states. Therefore, they mesh states that do not support RES-E with states that support RES-E but do not employ a RPS. Although, a 36 state majority solely relies on the RPS, there is a 10 state minority2 that also introduced a FIT in different years. And there are two more states3 that do not employ a RPS but a FIT (DSIRE, 2010). It is controversial to merge these 12 states with the 14 states minority4 that neither support RES-E by means of a RPS nor by a FIT. Of course, RPS and FIT differ with regard to the regulatory design. The RPS is a mode of quantity regulation that stimulates investment in RES-E by a command and control type of policy towards the utilities. It promotes RES-E technologies that come with a low cost since utilities can choose any available RES-E technology to meet their quota requirement. In contrast, the FIT is a mode of price regulation that stimulates investment by giving fixed price incentives to producers. It applies technology specific subsidies in order to equalize attractiveness for investment among different RES-E technologies. Therefore, investors can expect (more or less) the same return of investment regardless of their actual technology specific cost of electricity generation.5 A FIT challenges the utilities’ 2. Year of FIT enactment: 1997: MA, MN; 2004: PA, NJ; 2005: WA; 2006: CA; 2007: MD, SC; 2009: ME, OR, HI, VT (DSIRE, 2010). 3. 2004: NJ, SC (DSIRE, 2010). 4. AL, AK, AR, FL, GA, ID, IN, KY, LA, MS, NE, OK, TN, WY (DSIRE, 2010). 5. See Menanteau et al. (2003) for further details on price and quantity driven RES-E policy tools. In addition, see Couture and Gagnon (2010) for a comprehensive depiction of different types of FIT systems. Copyright 䉷 2012 by the IAEE. All rights reserved. 4 / The Energy Journal grip on the production park because it enables new producers to feed electricity into the grid. Thus, many renewable power plants with little capacity can substitute the mostly large power plants operated by the energy utilities. Despite these differences in design, there are two essential similarities. First—and this is important for the consumer side—the end user pays the bill that may increase because utilities forward additional costs to the end user. Second— and this is important for the kind of research—both policies share the goal of promoting investment in RES-E capacities. This aspect matters since we are asking why (not how) policymakers implement RES-E support schemes. Therefore, we should sample our cases by their policymakers’ intention not the type of policy tool they use. Results might change if the U.S. studies assembled their data according to this criterion. The reason is that the year of enactment would change in countries that apply regulation regardless of the regulatory design. The change in time is crucial to the regression coefficients since the studies do not conduct a cross-section analysis but a time series cross-section analysis. New Jersey and South Carolina would switch groups from non-regulation to regulation since they apply a state level FIT but do not employ a RPS. Minnesota and Washington would change from 2007 and 2006 to 1994 and 2005, respectively, because their FIT systems have been enacted prior to the RPS implementation (DSIRE, 2010). As a consequence, the study at hand runs regressions with a combined dependent variable, putting the implementation of feed-in-tariffs and quotas into one basket. Nonetheless, the discussion section also provides findings from models that test dichotomous variables of feed-in-tariffs and quotas separately. 3. THE PROPORTIONAL HAZARD MODEL In formal terms, this article’s aim is to ask what drives a country c to adopt regulation in a certain year t . Therefore, the dependent variable is a binary code distinguishing between regulation c(t)⳱1 and non-regulation c(t)⳱0. The proportional hazard model tests the impact of the independent variables X on the relative odds k of the conditional probability P1⳱P(t,X) of a country to adopt regulation in a certain year, given the country did not adopt such regulation before: P0⳱1– P(t,X). The relative odds k of a country to adopt regulation for the first time are expressed by P1/P0. k(t)⳱ P(t,X) 1– P(t,X) (1) If X is assumed to have no impact, we receive the relative odds k0 of the conditional baseline probability. k0(t)⳱ P0(t) 1– P0(t) for X⳱0 (2) The baseline is an estimate of the mean values of the independent metrics. According to Kiefer’s (1988; 1989) widely used proportional hazard model, Copyright 䉷 2012 by the IAEE. All rights reserved. What Drives States to Support Renewable Energy? / 5 the relative odds k depend on a product of the conditional baseline probability k0(t) and an individual scaling factor (X,b). k(t,X,b,k0)⳱k0(t) (X,b) (3) Please note that t does not impact the individual scaling factor (X,b) but the baseline hazard k0(t) . Lyon and Yin (2010) as well as this article proceed by replacing the individual scaling factor by the specification (4) that is often used in labor economics and other research that work with duration data. (X,b)⳱exp(X⬘b) (4) Applying (1), (2) and (4) to the proportional hazard model produces the relative odds of transition (5). The logit is shown in (6). P(t,X) P (t) ⳱ 0 1– P(t,X) 1– P0(t) exp(X⬘b) logit(P(t,X))⳱logit(P0(t))ⳭXb (5) (6) Deriving X yields the first order condition of the proportional hazard model including the specification case. d logk(t,X,b,k0) ⳱b dX (7) According to (7), a change in X affects k by the constant term of b. In other words, a one unit change of an independent variable alters the probability of a state to transit to regulation in a certain year by b. 4. INDEPENDENT VARIABLES There are various ways to explain the puzzle. Reviewing the literature mentioned above, we distinguish between public interest theory, private interest theory and a group of controls. Private interest theory assumes social groups that are affected by regulation to mobilize in order to influence policymaking according to their preferences. In turn, the policymaker responds to the efforts of the groups. Peltzman (1976) introduced the focus on interest groups as an explanation for the adoption of regulation. Becker’s (1983) model of interest group competition relates a group’s lobbying benefits to its lobbying ability. As Knittel (2006) puts it, the stronger a certain interest group, the higher the probability of a state to adopt regulation that benefits this group and vice versa. From an empirical stance, RESE support schemes affect two types of stakeholders: groups that seek rents from Copyright 䉷 2012 by the IAEE. All rights reserved. 6 / The Energy Journal RES-E support and groups that would lose their previous rents from fossil electricity sources (FES-E) because RES-E substitutes them. To capture this, we take quantifications similar to the ones applied in the U.S. studies. • ISES is a variable that indicates the years of existence of a state chapter of the International Solar Energy Association. Lyon and Yin (2010) test for its sister organization, the American Solar Energy Association (ASES). • UTIL is a proxy variable representing the market power of utilities on state electricity markets. Data is taken from a OECD survey that quantifies power market concentration on a horizontal and vertical dimension on a one to six scale (Conway and Nicoletti, 2006). • ATOM is a variable that indicates the years of existence of a national nuclear association that is allied with the European Atomic Forum (FORATOM), a trade association that rallies for nuclear energy in Europe. Private interest theory supposes ISES to have a positive effect on the dependent variable because RES-E lobby groups and their industries are potential beneficiaries of RES-E supportive regulation. In contrary, UTIL and ATOM are predicted to counter this effect since conventional power suppliers would be challenged by the new policy supported RES-E suppliers. Public interest theory assumes the policymakers to have a vital interest in helping to produce public goods such as clean air, employment and affordable energy. According to pure private interest theory, the policymaker is the agent of the interest groups. In public interest theory, the policymaker’s principal is the society as a whole instead. Energy consumers and taxpayers as huge parts of society make up the electorate to which the policymaker is accountable. Thus, the adoption of RES-E support schemes may also depend on their costs for society. In order to quantify the degree to which a society can afford to replace relatively cheap FES-E by costlier RES-E, we fall back on GDP per capita and the electricity price for private end users. To cover the industrial dependence on affordable power, we test for the energy consumption to GDP ratio. Data has been provided by Eurostat (2010). • GDP represents the gross domestic product per capita. • EPPC stands for the electricity price per kwh for private consumers. • EINT quantifies the energy intensity as the ratio of total energy consumption in Btu per 1,000 US-Dollars of GDP. Following the U.S. studies and public interest theory, the poorer a country, the lower its likelihood of RES-E support. Conversely, we predict a positive link between GDP per capita and the dependent variable. The same logic can be applied to private and industrial consumers. Hence, we expect EPPC and EINT to lower the odds. Copyright 䉷 2012 by the IAEE. All rights reserved. What Drives States to Support Renewable Energy? / 7 Beside these cost aspects, there are possible benefits for society that may increase the likelihood of policy adoption. RES-E investment stimuli created approx. 550,000 new workplaces in Europe since 1990; 150,000 in 2008 and 2009 alone (EREC, 2010). The replacement of PM10 rich FES-E by RES-E technologies is another public good. Thus, reducing the public bad of air pollution can attract policymakers to adopt regulation. Therefore, we predict the likelihood to increase with a rise in UEMP or AIR, respectively. • UEMP is the state unemployment rate as a percent of total work force. Data has been provided by Eurostat (2010). • PM10 is a metric for national air pollution. It represents the total particulate formation as an equivalent to 10,000 tonnes of PM10. Data has been provided by the European Environment Agency (2009). In an array of regressions, we control for further variables that have frequently been brought up by qualitative analyses and the U.S. studies mentioned above. We run robustness checks with controls separately and in combined models. • NBOR is the ratio of neighbor states that have already implemented RES-E support schemes and the total number of neighbor states. Chandler (2009) introduced learning effects between U.S. neighbor states. We applied his indicator to the EU27 sample. • GREEN stands for the number of parliamentary seats that are occupied by the national Green party. Data has been provided by the European Green Party (2010). This indicator mirrors the party indicators for the Democratic or Republican party variables in the U.S. studies. • EFAM is a categorical metric for the state’s electoral family. It distinguishes between majoritarian, combined and proportional electoral systems (Norris, 2009). We control for this polity aspect because the Greens, as a supposedly small party, have a structural disadvantage in two-party systems. • EU is a dichotomous indicator representing the EU Directive 2001/ 77/EC on RES-E. It has been the EU’s first binding directive that obliges state legislators to support RES-E. Marques et al. (2010) employs the very same dummy to control for the EU’s impact on RESE development. • SOL quantifies the solar energy potential as global radiation in kwh per square meter. Data has been provided by the Global Energy Network Institute (2010). The solar potential is classified into low (⬍1050 kwh/m2a), middle (1050–1599 kwh/m2a), and high (⬎1599 kwh/ m2a) degrees of radiation. Copyright 䉷 2012 by the IAEE. All rights reserved. 8 / The Energy Journal Table 2: Logit Regression Results on the Relative Odds of Policy Adoption Variable Model (1) Model (2) Model (3) ISES UTIL ATOM 1.331** (2.05) –2.836* (–1.8) –0.244 (–0.96) 3.766*** (2.94) –2.701* (–1) 0.672 (1) 1.948*** (4.27) –2.396* (–1.68) –0.214 (1.31) GDP EPPC EINT UEMP PM10 0.001 (1.6) –0.018 (–0.19) –2.712 (–1.41) 1.374*** (2.79) 0.042 (1.63) 0.001 (0.86) –0.074 (–0.42) –5.870 (–1.62) 2.619*** (2.68) 0.054 (0.54) NBOR GREEN EFAM EU SOL –5.060 (–0.7) –0.335 (–0.89) 25.741*** (2.82) 6.076 (0.78) 49.715*** (4.94) 0.905 (0.18) –0.203 (–1.45) 4.081 (1.37) 2.777 (0.96) 16.797*** (3.95) * p⬍0.1, ** p⬍0.05, *** p⬍0.01; t statistics in parantheses. 5. FINDINGS The estimations base on the EU27 sample from 1990 to 2010. The actual N of 237 is lower than the total N of 567 because cases are dropped from the sample as soon as a states adopts regulation in order not to bias the coefficients of the time series cross-section regression. Table 2 provides the outcome of three logit models. The first column presents the full model. The second model introduces the controls. Model three treats private interest variables and controls exclusively. Various additional model runs have verified the findings to be robust for separate and combined exclusion of private interest variables, public interest variables and controls. The “variance inflation factor” (VIF) tests for multicollinearity since the model runs on duration data. Studenmund (2009) suggests a VIF alert level of five. O’Brien (2007) finds designs which allow an even higher level. Neither the tested metrics nor their mean VIF ranges at or above the margin of five. Furthermore, the variables do not correlate among each other at or above the 0.7 level. We find four coefficients remaining at a significant level throughout the regression table at hand and the robustness check: ISES, UEMP, and SOL have a positive impact on policy adoption while UTIL comes with a negative effect onto the likelihood of policy adoption. 6. DISCUSSION The significant results provide evidence in support of private interest theory. In particular, the existence of lobby groups is associated with RES-E Copyright 䉷 2012 by the IAEE. All rights reserved. What Drives States to Support Renewable Energy? / 9 Table 3: Comparison of EU27 and U.S. findings Variable EU U.S. Solar Industry Nuclear Industry Oil and Gas Industry Coal Industry Ⳮ** – –***1 Market Concentration Restructured Market –* Private Interest –1 –1 –**1 Public Interest GDP Ⳮ Ⳮ*2 Electricity Price – –1 Energy Dependency – –3 Unemployment Rate Ⳮ*** –**1 Air Pollution Ⳮ Ⳮ1,3 Neighbor Effect Ⳮ Ⳮ**3 Green Seats Democratic Seats Republican Seats Liberal Government – Proportional Elec. System Ⳮ EU Directive 2001/77/EC Ⳮ Solar Potential Wind Ⳮ Solar Potential Wind Potential Ⳮ*** Controls Ⳮ***1 –**2 Ⳮ***3 Ⳮ***1 Ⳮ3 Ⳮ**1 * p⬍0.1, ** p⬍0.05, *** p⬍0.01. 1 Lyon and Yin (2010), 2 Huang et al. (2007), 3 Chandler (2009). policy adoption. Both links are consistent with Becker’s (1983) competition model. On the one side, solar interest groups come with a positive link to the dependent variable. As possible beneficiaries of RES-E investment, they have an incentive to lobby in favor of policy adoption. Thus, the coefficient is revealed to be positive. On the other side, previous rent-takers will be challenged by the legislation. Their efforts to curb motivation to support RES-E is expressed in the negative coefficient of UTIL, a proxy for utilities’ market power. Utilities have a disincentive to get RES-E legislation ratified because it allows new producers to enter the market, thus challenging their segment by decentralizing the production park. The ATOM indicator, representing another conventional power lobby, implies this interpretation to be correct, although it does not come at a significant level. As can be reviewed in Table 3 the findings for the conventional energy Copyright 䉷 2012 by the IAEE. All rights reserved. 10 / The Energy Journal interest groups and the market proxies are most consistent with Lyon and Yin (2010). Both metrics, UTIL and ATOM, have an implication for the choice between RPS and FIT. In the FIT scenario, the market entry barriers are lowered because new RES-E producers are legally entitled to feed electricity into the grid. Thus, conventional power suppliers—in many states used to their regional monopolies—are challenged at the production level. Loosing market shares, they have an incentive to lobby against FIT adoption. In the RPS scenario, they keep their grip on the production park. Such a quota scheme requires utilities to forward a certain RES-E share of their portfolio to the end user but it does not increase competition on the power production market by lowering barriers. Therefore, private interest theory would expect conventional power suppliers to favor a quota as a second best solution over a FIT as a third best solution, in case their first best solution of no regulation is no longer an option. Interestingly, the coefficient of the ATOM indicator changes from negative to positive if the FIT cases are excluded from the sample. The low number of quota cases in the EU27 sample however, does not produce significant results. The UTIL indicator switches back and forth which does not allow us to give stable interpretations. Intuition however would suggest the same explanation. Conventional power suppliers, represented by UTIL and ATOM, fight FIT adoption more decisively than RPS schemes. The regressions also provide support for the public interest hypothesis that weak labor markets encourage policymakers to shift incentives in favor of jobs in the renewable energy sector. At first glance, this is surprising because we would have expected policymakers to subsidize conventional power production in economically bad times. As can be reviewed in Table 3, the U.S. sample produces such a link. For the EU27 sample, the UEMP coefficient implies the contrary. The likelihood of policy adoption goes up with an increase in unemployment rate. This connection suggests that policymakers have left the stage of paying lip service to RES-E technologies in downturn phases only, now seriously betting on RES-E to create jobs. If the 2000 to 2010 data is excluded from the sample, the coefficient turns negative. An explanation can be that prior to 2000, policymakers relied on FES-E. With growing struggles that have been mentioned in this article’s very first sentence, there has been a shift in labor market policy in favor of job creation in the renewable energy sector in Europe. Continued jobless industrial growth may also shift strategies of U.S. unemployment policy in the future. Other public interest indicators do not stand up to scrutiny. They produce the same signs as have been presented in the U.S. studies. On both sides of the Atlantic, GDP per capita seems to slightly increase the probability of RES-E support, allowing for the claim that a state needs to be prosperous enough to support RES-E. This interpretation is supported by the negative link between the electricity price and the likelihood of adoption. Air pollution, quantified by the PM10 indicator, captures what public theory claims about a policymakers task to help producing the public good of clean air. Although GDP, EPPC, and PM10 do Copyright 䉷 2012 by the IAEE. All rights reserved. What Drives States to Support Renewable Energy? / 11 not meet significance criteria, the convergence with the significant U.S. findings indicates that the theory itself is on the right track. The control variables neither reject predictions nor do they provide significant connections. The solar potential is the exemption to the rule. Sunny places appear to be more attractive for policymakers to adopt RES-E regulation. The impact is even higher if we take the PV feed-in-tariffs as the dependent variable. High solar radiation increase the return of investment in solar power systems of course. This hypothesis has been verified by Lyon and Yin (2010) as well. As has been pointed out by Chandler (2009) for the U.S. states, we can also speak about state-to-state learning effects in the EU. The low significance level does not allow for verification however. The same can be said about EFAM, a categorical metric that classifies the electoral system, and the EU dummy. Green seats do not seem to make significant difference—a claim that has been put forward by Laird and Stefes (2009) in a comparative case study for the U.S. and Germany. Very generally speaking, the article concludes that private interest hypotheses come close to reality. They emphasized that supporter groups boost while opposed groups block RES-E legislation. (a) The existence of a solar energy association increases the probability of a state to adopt regulation. (b) Solar radiation, and (c) the unemployment rate also increase the odds. (d) Electricity market concentration decreases the probability of transition. Interestingly, the nuclear society indicator as well as the market concentration indicator turn positive if we exclude the FIT cases from the sample. We suggest that utilities favor quotas over feed-in-tariffs because the latter can challenge their grip on the production park. REFERENCES Becker, G.S. (1983). “A theory of competition among pressure groups for political influence.” The Quarterly Journal of Economics 98(3): 371–400. http://dx.doi.org/10.2307/1886017. Chandler, J. (2009). “Trendy solutions. Why do states adopt Sustainable Energy Portfolio Standards?” Energy Policy 37(8): 3274–3281. http://dx.doi.org/10.1016/j.enpol.2009.04.032. Conway, P. and G. Nicoletti (2006). “Product market regulation in the non-manufacturing sectors of OECD countries: Measurement and highlights.” OECD Publishing, OECD Economics Department Working Paper #530. Couture, T. and Y. Gagnon (2010). “An analysis of feed-in tariff remuneration models: Implications for renewable energy investment.” Energy Policy 38(2): 955–965. http://dx.doi.org/10.1016/ j.enpol.2009.10.047. DSIRE (2010). “Database of State Incentives for Renewables and Efficiency.” July. Accessed at http:// www.dsireusa.org/. European Environment Agency (2009). “Greenhouse gas emission trends and projections in Europe 2009.” European Environment Agency. EEA Report 9/2009. Brussels. European Green Party (2010). “National Results Archive.” September. Data provided by the European Green Party. Brussels. European Renewable Energy Council (2010). RE-thinking 2050. European Renewable Energy Council. Brussels. Eurostat (2010). “Statistics Database.” July. Accessed at http://epp.eurostat.ec.europa.eu. Global Energy Network Institute (2010). “Library. Solarenergy in Europe.” July. Accessed at URL http://www.geni.org/globalenergy/library/. Copyright 䉷 2012 by the IAEE. All rights reserved. 12 / The Energy Journal Heymann, M. (1998). “Signs of hubris. The shaping of wind technology styles in Germany, Denmark, and the United States.” Technology & Culture 39(4): 641–670. Huang, M.-Y., J.R. Alavalapati, D.R. Carter and M.H. Langholtz (2007). “Is the choice of renewable portfolio standards random?” Energy Policy 35(11): 5571–5575. http://dx.doi.org/10.1016/ j.enpol.2007.06.010. Joskow, P.L. (2009). “Foreword: US vs. EU electricity reforms achievement” In F. Leveque and J.M. Glachant , Electricity reform in Europe: towards a single energy market. Chatenham: Edward Elgar. 13–29. Keller, S. (2010). “Sources of difference. In answer to the article about diverging paths of German and US policies for renewable energies.” Energy Policy 38(8): 4741–4742. http://dx.doi.org/ 10.1016/j.enpol.2009.10.035. Kiefer, Nicholas M.; G.R. Neumann (1989). Search models and applied labor economics. Cambridge: Cambridge University Press. Kiefer, N.M. (1988). “Economic duration data and hazard functions.” Journal of Economic Literature 26(2): 646–679. Knittel, C.R., 2006. “The adoption of state electricity regulation. The role of interest groups.” Journal of Industrial Economics 54(2): 201–222. http://dx.doi.org/10.1111/j.1467-6451.2006.00280.x. Laird, F.N. and C. Stefes (2009). “The diverging paths of German and United States policies for renewable energy: Sources of difference.” Energy Policy 37(7): 2619–2629. http://dx.doi.org/ 10.1016/j.enpol.2009.02.027. Lauber, V. and L. Mez (2004). “Three decades of renewable electricity policies in Germany.” Energy & Environment 15(4): 599–623. http://dx.doi.org/10.1260/0958305042259792. Lyon, T.P. and H. Yin (2010). “Why do states adopt renewable portfolio standards? An empirical investigation.” The Energy Journal 31(3): 133–157. http://dx.doi.org/10.5547/ISSN0195-6574-EJVol31-No3-7. Marques, A.C., J.A. Fuinhas and J. Pires Manso (2010). “Motivations driving renewable energy in European countries. A panel data approach.” Energy Policy 38(11): 6877–6885. http://dx.doi.org/ 10.1016/j.enpol.2010.07.003. Menanteau, P., D. Finon and M.-L. Lamy (2003). “Prices versus quantities. Choosing policies for promoting the development of renewable energy.” Energy Policy 31(8): 799–812. http://dx.doi.org/ 10.1016/S0301-4215(02)00133-7. Norris, P. (2009). Democracy crossnational data. Tech. Rep. 3, Cambridge MA.: Harvard University. O’Brien, R.M. (2007). “A caution regarding rules of thumb for variance inflation factors.” Quality and Quantity 41(5): 673–690. http://dx.doi.org/10.1007/s11135-006-9018-6. Peltzman, S. (1976). “Toward a more general theory of regulation.” National Bureau of Economic Research. NBER Working Paper #0133. Rabe, B.G. (2004). Statehouse and greenhouse. The emerging politics of American climate change policy. Washington D.C.: Brookings Institution Press. Renewable Energy Policy Network for the 21st Century (2009). “Renewables. Global status report. 2009 update.” Renewable Energy Policy Network for the 21st Century. Paris. Res-legal (2010). “Legal sources on renewable energy.” July, accessed at http://res-legal.eu/. Studenmund, A.H. (2009). Using econometrics. A practical guide, Boston: Pearson. Copyright 䉷 2012 by the IAEE. All rights reserved.