Sarah Egener April 9, 2015 ENVS 3020

A Literature Review:

Analysis of Renewable Energy Portfolio Standards in the U.S.

Abstract A review of literature examining renewable energy portfolio standards in the United States. Through meticulous evaluation of journals, this literature review examines the findings and methods of previous studies regarding these renewable energy standards. By setting the scene with a background in the standards, meaning their history and design, this literature review then delves into what types of trends, impacts, costs, benefits, and alternatives of renewable portfolio standards have presented thus far in their existence. The data incorporated in this review comes from a variety of research methods, including social, economic, and statistical perspectives. With a firm grasp on the current status of renewable portfolio standards in the United States, this review of literature then prompts further research within the question of whether a federal portfolio standard is feasible and down a path worth exploring for our nation and its renewable future. Introduction It has been quite difficult for the United States to take real action and incorporate renewable

energy sources into viable usage. Within this lackadaisical mindset sprouted some new standards that

would eventually pick up speed and prove to make substantial progress into our modern day. Renewable

portfolio standards (RPS’s) have emerged as one of the most important policy drivers of renewable

energy capacity expansion in the U.S. They are a type of legislation that cracks down on environmental

initiatives and works with the economic sector in order to get renewable energy generation on the

electrical grid once and for all, all at the state level. With all of the attempts to increase renewables that

have not made substantial progress, could renewable portfolio standards finally be that regulation that

puts forth real results? This literature review aims to investigate some of the many internal and external

factors associated with renewable portfolio standards including trends, impacts, costs, benefits, and the

alternative of feed-in tariffs through previous studies done by credible researchers. With the

accumulation of prior literature this review aims to assess the current status of RPSs and where the

United States stands in terms of a federal standard that applies to all different types of states with

varying resources, finances, utilities, ideologies, and more.

Background Design Renewable energy portfolio standards (RPSs) are pieces of legislation that require retail power

suppliers to purchase a certain amount of renewable energy credits or certificates (RECs) in proportion

it its total kilowatt-hour (kWh) energy sales. These RECs are energy commodities that only pertain to

the U.S. and provide evidence that 1 kWh was generated from a renewable energy source. They are

intangible yet tradable, and are basically the monetary system involved when hitting those renewable

energy standards. Retail suppliers can certify their own RECs through their own renewable facilities or

purchase RECs from other facilities directly from renewable generation or a REC broker (Rader, 1996).

Agstar additionally examines the RPS in an unbiased manner by delivering the key features of the

standards and the requirements that they necessitate. The goals of RPS can be environmental, economic,

technological, etc. and range from local to global scales. RPS applicability is most commonly applied to

investor-owned utilities and electric service providers. While municipal and cooperative utilities are

self-regulated, states have made specific revisions to their RPS’s to allow municipalities and

cooperatives to voluntarily adopt the standards. Eligibility for RPS depends on geographical location,

resources, technologies, facilities, and whether they align with goals (Agstar, 2014). Anthony Paul, a

colleague of later literature author Karen Palmer, outlines how RPS policy is modeled with targets,

timetables, and compliance payments. He actually compares the RPS design to the American Clean

Energy and Security Act of 2009 (H.R. 2454). Whereas this bill allows for energy savings from

investments to count towards the standard, RPS’s do not include this feature in their design and instead

involves alternate compliance payments, which is an extremely important aspect (Paul, 2011).

History Gonzalo Frances analyzes the conditions leading up to RPS construction and development. With

a perspective concerning preconditions, Frances studies how environmental issues of the 20st century

allowed renewables to gain momentum. Many pollution and climate change concerns slipped into the

realm of public awareness and encouraged governmental policies. Renewable energy source promotion

along with energy efficiency measure would combine into many of the policies we know and use today.

As a result, Frances concludes that these efforts are what have instilled renewable development since the

start of the 21st century have been great. Though Frances delves into RPS’s in his study, he focuses

mainly on policies as a whole (Frances, 2013). Christopher Namovicz from the Electricity Journal

discloses RPS origin in his studies. Thoughts and design of RPS’s first sprung up in California in 1995.

With its actual implantation in 2002, renewable energy advocates across the country started expressing

their desire for similar standards everywhere. Through stand-alone legislation, one by one states have

adopted their own RPS versions. Namovicz refers to this process as “market-friendly” because it is a

requirement that does not allocate lots of government funding. He includes a visual chart in his study

that not only portrays state enactments of RPS’s but also illustrates any revisions made throughout RPS

history, and this can be seen below. Through text and visuals, this literature author introduces RPS’s

through understandable description (Namovicz, 2007).

(Namovicz, 2007)

Current Status 29 states and the District of Columbia to have mandatory renewable requirements within their

total generation and 8 states to have goals for mandatory requirements in the process, and this can be

visualized with the percentage of total generation and by what year in the image below (Jenkins, 2013).

These RPS’s are present in both restructured electricity markets and in cost-of-service-regulated markets

So far, no state has gone back and repealed any of their RPS legislation that has already been enacted. In

fact, RPS’s that have not gone untouched have only been strengthened by raising the percentage of

renewable energy produced within the overall generation. Though this literature focuses solely on the

United States, there are renewable mandates across the world in forms of quotas, obligations, certificate

programs and more in nations such as the U.K., Sweden, Belgium, Italy, Poland, Japan, Australia, and

more (Wiser, 2014).

(Jenkins, 2013)

Summary of Research Trends Jess Chandler from Science Direct’s Energy Policy Journal examines the trends in which states

adopt RPS while considering their diverging internal circumstances as well as external innovation.

Through statistical analysis of logistic regression, Chandler examines many independent variables

against the independent variable: renewable portfolio standards. By listing the variables and their

impacts it becomes apparent what key players have a say in the trends in which RPS’s are adopted, and

these are explained as followed. The first independent variable that Chandler assesses is population

growth rate, which is actually behind 1 year because of the information available to policy makers when

drafting legislation. Per capita disposable income is a variable used in order to measure income of U.S.

states, which is also behind 1 year, and measured in hundred thousands of dollars in order to accurately

align with the percentages of the other variables. The non-attainment variable refers to the percentage of

population living in an area considered to have worse air quality than what the National Ambient Air

Quality Standards define as safe. The variable of renewable potential consists of the amount of solar and

wind potential in proportion to total electricity sales. Electricity intense industry variable indicates the

percent of gross state product coming from electricity intense industries and is basically used to

calculate the dependence of a state’s economy on electrical consumption. On the other hand of raw data

are more societal implications, like the variable of government ideology, which indicates where the

state’s political stance and social opinions reside. Ideological distance is a very interesting variable

because it examines the adoption rate in which states take on standards depending on what their

neighboring state has done or plans to do. Once the variables are listed, a logistic regression model is

outlined and visualized through text but mostly charts. This brings about the statistical side of my

research question and introduces mathematics into its answer. When projecting outcomes, in this case

the trends of these standards, it is always an important approach to take because of how data can be

assigned numbers and crunched through algorithms in a more objective manner. The results show that

regional and neighbor diffusion variables are significant in RPS adoption decisions—even when

accounting for ideological distance from previous adopters. While Chandler breaks down RPS trends to

numbers and regression and pinpoints some significant players, statistics always have some limitations.

In this study, the adoption predictions were not consistently lined up with the adoptions that have

already happened. Furthermore, while a variable may not prove usefulness in this study in particular, it

cannot be completely excluded. For example, in the regression, the non-attainment variable did not

express significance, but in the broader RPS picture, air quality is definitely going to factor into whether

a state had a need for more renewables (Chandler, 2009).

Impacts Yin Haitao, assignment professor at Antai College of Economics and Management, accumulates

research on existing empirical data on RPS impact. In his journal he exclaims how studies previous his

own have used cross-sectional approaches that over-simplify RPS impacts and overlook diverging

designs for different states. This study seeks to measure RPS impact in a way that accounts much for

specific RPS design features and how those affect its strengths (Haitao, 2009). Energy Policy Journal’s

Andy Kydes also analyzes RPS impact on electricity but also on fossil fuel usage. Kydes exclaims that

RPS policy reduces the construction of gas and coal generation technologies that would have been built

otherwise. Therefore, in 2020 the RPS initiative is projected to cancel around 96 GW of less coal units

and create 166 GW of more renewable units (99 GW of that being wind capacity) (Kydes, 2006).

Social Implications Chelsea Schelly, whose findings are also featured in Science Direct’s Energy Policy Journal,

reports on the sociological impacts of renewable portfolio standards. She does this by narrowing in on

the residential sector of energy usage and how renewables can integrate into daily household practices.

Before even getting into RPS’s, she more broadly examines how values influence the choices that

people make. This is an important distinction to make because depending on one’s environmental,

economic, conservational, etc. values, his or her take on RPS are going be affected. This is largely why

no two state RPS policies are exactly the same in types of design including types of energy and year

goal must be reached by. Schelly investigates how Colorado’s RPS (requiring 30% renewables by 2020)

was instigated by a ballot initiative that was desired by its own voters and speaks towards values of

Colorado residents. She pinpoints a specific energy source and situation to explain societal implications

of these standards. Her study investigates the interviews done amongst homeowners who have installed

residential solar electric technology in Colorado. The majority of residents interviewed happened to

retired or close to retirement. The social explanation for this is that they may have had much more time

to accrue the savings for the upfront cost of solar panels and they plan on staying put in their current

residence for some time. This is just a specific example amongst many studies that aim to pinpoint

sociological reasoning behind renewable adoptions after Colorado has embraced its latest RPS. The

major goal of this piece of literature was to understand residential motivations and experiences with

renewables (Schelly, 2014).

Costs SciTech Connect journal composed by Ryan Wiser is a comprehensive review of the existing

costs of renewable portfolio standards along with the methods in which he calculates these cost

estimates. Strictly from an economic and statistical perspective, his analysis is based on the incremental

cost of RPS targets. Renewable portfolio standard compliance costs are compared against renewable

energy certificates. This data is accumulated via cost estimates reported by utilities and regulators and

translated into common metrics for balanced units across the board. From 2010 to 2012, average RPS

compliance costs were equal to 0.9% of retail electricity rates when calculated as a weighted-average.

More recently, costs have transitioned to 2% of average retail rates for most states. Wiser discloses that

the comparisons across states are imperfect due to the varying methods and assumptions used in the

specific standards. The use of REC prices to compute RPS compliance costs in restructured markets are

limited in some cases by a lack of REC price transparency and incomplete data on long-term contracts

(Wiser, 2014). Trent Berry, also with the Energy Policy Journal of Science Direct, discusses why

renewable costs are the way that they are. His exclaims that although renewables involve newer, more

expensive technologies, the government puts forth several mechanisms such as grants, loans, indirect

support, and the renewable portfolio standard. Berry utilizes surveys from across the world to

investigate RPS cost effectiveness. Narrowing in on the United States, RPS costs face risks of driving up

electricity prices when the targets are set too high. But in order to minimize this risk, cost caps have

been implemented for renewables. Through his findings and surveys, Berry suggests the cost cap. If

electricity providers are using REC’s, then program administrators can set an unlimited amount of

REC’s that is equal to the price cap. Berry acknowledges that RPS costs are a significant concern across

the country, and his studies aim to find solutions to these worrisome costs (Berry, 2000). Lord Bird’s

research from the Energy Policy Journal of Science Direct inspects the National Renewable Energy

Lab’s Regional Energy Deployment System (ReEDS) model that examines the least-cost expansion of

electricity generation capacity and transmission in the United States. This model examines prices and

emissions caps / carbon emissions with RPS individually and combined. By comparing RPS and carbon

cap scenarios, the effect of varying level caps are observed while the RPS remains constant. On the

other hand, Bird evaluates varying RPS costs while the carbon cap is held steady. Her findings from

these processes divulge that, specifically with costs, that RPS’s do not result in substantial electricity

price increase. Though there is greater technology investment, fuel costs are reduced and offset the

impact on average power prices (Bird, 2011). Cliff Chen with the Renewable and Sustainable Energy

Reviews Journal on Science Direct considers the cost-impact analysis of the RPS’s implemented since

1998. Similarly to previous cost findings being reviewed, Chen confirms that 70% of state costs studies

in the U.S. have electricity rate increase no greater than 1% when RPS is involved. Chen accumulates

this data via models containing RPS policies of 20 U.S. states and the key findings are highlighted in

project costs and input assumptions (Chen, 2008). Gabriella Stockmayar and her journal within Science

Direct’s Energy Policy studies are a bit more unbiased with her RPS cost analyses. Her paper describes

the ways states try to control their RPS costs and while the strengths are included she does not shy away

from the weaknesses they pose. She discloses that implementing RPS’s will never come free and while

utilities and regulators are trying to mitigate costs, one preferred cost limitation approach will never

work in all state cases. Stockmayar’s survey work suggests that the most important factors in curtailing

costs are clarity, consistency, and above all, transparency for customers (Stockmayar, 2011).

Benefits Whereas Wiser examined costs literally based on pricing and economics, with benefits he

expands his strategy and observes the broader social benefits beyond any direct cost savings that may

accrue to utilities. The potential benefits of RPS policies that he scrutinizes include reduced emissions,

water savings, fuel diversity, electricity price stability, and economic development. While many times

U.S. states have attempted to quantitatively assess these benefits, in other cases state legislatures or

public utility commissions require these assessments as part of integrated resource plans (IRP’s) in

preparation for regulatory commissions, energy boards, or public benefit corporations. Wiser’s study

acknowledges how benefits of RPS’s are actually necessary components that states need to know about,

which makes perfect sense. For Wiser’s findings I narrow in specifically on his qualification of

emissions and human health benefits. He uses model approaches to assess scenarios of air quality with

and without renewable energy for comparisons. He also estimates the dollar values associated with

emission reductions in order to monetarily compare them into the economic sector. Specifically, these

emission benefits are estimated into net incremental costs, which when calculated out, range from tens

to hundreds of millions of dollars in savings annually (Wiser, 2014). Chuck Kutscher of the National

Renewable Energy Lab delves specifically into the RPS impacts in Colorado. His study aims to assess

the renewable and carbon impacts currently in place and what has happened since Colorado’s RPS was

increased from 20% to 30%. This is all done through a user input-drive Microsoft Excel model with

assessments of technology, electrical outputs, and carbon reduction for both 20% and 30%. Kutscher

finds that the 30% RPS succeeds in meeting the carbon restrictions necessary to avoid climate change’s

worst impacts, meaning Colorado’s RPS increase has posed environmental benefit. What is most

interesting about this study is that when the author was accumulating this data, Colorado had not

actually increased its RPS to 30% yet, so for Kutscher these conclusions were only hypothetical at the

time (Kutscher, 2007). Though dealing with costs, A. Mahone’s studies in the Energy Policy journal

suggest investment in cost-effect energy efficiency that RPS’s bring about. Using California as a case

study, Mahone demonstrates how RPS benefits can be especially reaped if resource allocation is

improved through energy efficiency (Mahone, 2008). Simone Epsey from the Energy Policy Journal

discusses the main support mechanisms for RPS due to the fact that open market conditions and price

regulation mechanisms favor renewable energies. She analyzes how creating a demand side for

renewable energy first instead of the supply side is a spreading tool. While RPS’s focus on the demand

side, Epsey studies how the higher competition among generators along with the RPS will allow more

freedom of choice on the supply end for meeting requirements (Epsey, 2000).

Differing Opinions RPS vs. Alternatives Scott Hempling and his journal published by the National Renewable Energy Lab define and

analyze feed-in tariffs (FIT’s), an infamous alternative to the RPS. These tariffs obligate retail utilities to

purchase electricity from renewable generators with very specific guidelines. These create a continuing

obligation in the local utility to buy output from renewable producers at standardized rates associated

with generation costs and certain terms and conditions. FIT’s differ from RPS in that they make use of

long-term agreements. Beyond explanation of the alternative, Hempling raises the constraints placed on

FIT’s due to policies in U.S. history. Interestingly, there are features within the designs of the Public

Utility Regulatory Policies Act (PURPA) of 1978 and the Federal Power Act of (FPA) of 1935 that

constrain the transaction of wholesale sale of electricity from renewable generator to retail utility. This

study then prompts Hempling to seek ways in which states can free themselves of these constraints and

put these tariffs to use (Hempling, 2010).

In Science Direct’s Renewable Energy Policy journal, Peng Sun compares his research on two

regulatory policies. This literature review as a whole focuses on renewable portfolio standards, and Sun

examines RPS’s with the alternative policy of feed-in tariffs. Through a two-stage model, Sun compares

RPS to feed-in tariffs by setting up a scenario in which a monopolization firm has a productivity level

and the associated amount of energy required. Then, in one consequence RPS effects are added and in

another consequence FIT effects are incorporated. What Sun finds through this model is that FIT’s are

more efficient than RPS when increasing the quantity of installed capacity of renewable energy and

stimulating productivity to reduce costs. However, RPS prove to be more efficient when reducing

carbon emissions and improving consumer surplus. Sun chooses to neglect social welfare impacts of

each regulatory policy due to the fact that it depends a lot on negative externalities; a topic this research

does not quite delve into as much (Sun, 2014).

Abolhosseini also acknowledges alternatives employed by governments in order to finance

renewable energy development programs. His research supports promising policies that require

renewable energy in investment of small-scale energy production systems. His studies also find that

FIT’s are desirable in certain circumstances, like renewable energy investments that want low-risk,

whereas RPS’s are more appropriate regarding government employed market policies. Additionally

Abolhosseini considers tax incentives in order to adopt carbon emission taxes or emission trading

mechanisms in order to mitigate emissions at lower costs but somewhat indirectly make renewables

more appealing in that way. This study in particular, though it does not crunch so many numbers as

other studies, still considers technological progress, cost reduction, and financial input (Abolhosseini,

2014).

Jared Moore from Science Direct’s Energy Procedia Journal takes a look into low carbon

capacity standards (LCCS’s) as an alternative to RPS for lowering electricity carbon emissions. LCCS’s

create requirements for load-serving entities to move onto new low carbon capacity and provide greater

balance of energy than a RPS, according to Moore. Though cost of new entry estimates, Moore’s

research suggests that with LCCS’s coal fired power plants utilizing carbon capture and sequestration

would have the lowest cost per MW of all low carbon technologies. Moore’s studies come with bias

against RPS and take a route that does not necessarily consider renewables, if the costs are lower for

carbon capture and sequestration as an environmental method (Moore, 2014).

Question of Further Research It is no question that the United States is entering a critical phase of renewable-energy

policymaking. Currently Congress is debating national renewable-energy policy, which leads me to my

question that requires further research. Brent Haddad and his journal continues the dialogue on

alternative approaches to ensuring that public benefits from renewable-resource electricity but

throughout the entire country. In this article, he argues that there are valid reasons for federal

government intervention because of the benefits renewable resources provide to society that are not

captured by the price of electricity. These benefits; greenhouse-gas mitigation, society-wide price-

stability benefits, and long-run national energy-independence should be enjoyed by every inhabitant of

the United States (Haddad, 1999). The Energy Policy Journal also hosts Karen Palmer’s research on the

federal debate of RPS’s. She also suggests cap-and-trade and tax credits on a federal level, suggesting

that RPS’s will have competition as an environmental policy across the country. She specifically

analyzes the Haiku electricity market model to evaluate the economic, technological, environmental,

and cost-effectiveness of RPS’s and its alternatives on a federal level. While RPS’s world substantially

use renewables across the nation, Palmer finds that cap-and-trade programs (CTP’s) are much more

successful in reducing carbon emissions because it distinguishes coal and natural gas electricity, making

it most cost-effective. The point of Palmer’s research in this review is that RPS may not be as feasible as

other policies on a federal level (Palmer, 2005). There are many political figures across the country that

push for federal RPS’s. Thomas Udall, senator from New Mexico, is on congressional record for

amendment of the Public Utility Regulatory Policies Act of 1978 in order to prescribe guidelines for a

federal renewable portfolio standard from 2008 to 2037. Though these attempts were made back in

2005, Udall puts forth some major arguments including graduated annual percentages of supplier base

amounts, encourages federal, municipal, and rural utilities and cooperatives to participate in the RPS

program, and to establish a state renewable energy account program. It is the content and incentives

behind Udall’s encouragement that matters for future questions of federal RPS (Udall, 2005).

Bibliography

Abolhosseini, Shahrouz. “The Main Support Mechanisms to Finance Renewable Energy Development.” Accessed

March 12, 2015. http://www.sciencedirect.com/science/article/pii/S1364032114006893. Agstar. “Renewable Portfolio Standards | AgSTAR | US EPA.” Accessed March 17, 2015.

http://www.epa.gov/agstar/tools/funding/renewable.html. Berry, Trent. “The Renewable Portfolio Standard:: Design Considerations and an Implementation Survey.”

Accessed April 9, 2015. http://www.sciencedirect.com/science/article/pii/S0301421500001269. Bird, Lori. “Evaluating Renewable Portfolio Standards and Carbon Cap Scenarios in the U.S. Electric Sector.”

Accessed April 9, 2015. http://www.sciencedirect.com/science/article/pii/S0301421511001054. Chandler, Jess. “Trendy Solutions: Why Do States Adopt Sustainable Energy Portfolio Standards?” Accessed

March 17, 2015. http://academic.research.microsoft.com/Publication/40877152/trendy-solutions-why-do- states-adopt-sustainable-energy-portfolio-standards.

Chen, Cliff. “Weighing the Costs and Benefits of State Renewables Portfolio Standards in the United States: A

Comparative Analysis of State-Level Policy Impact Projections.” Accessed April 9, 2015. ://www.sciencedirect.com/science/article/pii/S1364032108000075.

Epsey, Simone. “Renewables Portfolio Standard: A Means for Trade with Electricity from Renewable Energy

Sources?” Accessed April 9, 2015. http://www.sciencedirect.com/science/article/pii/S0301421500001579. Frances, Gonzalo. “RES and Risk: Renewable Energy’s Contribution to Energy Security. A Portfolio-Based

Approach.” Accessed April 9, 2015. http://www.sciencedirect.com/science/article/pii/S1364032113003924. Haddad, Brent. “Forging Consensus on National Renewables Policy: The Renewables Portfolio Standard and the

National Public Benefits Trust Fund.” Accessed April 3, 2015. http://www.sciencedirect.com/science/article/pii/S1040619098001250.

Haitao, Yin. “Renewable Portfolio Standards: True Commitments or Pure Symbols?” Accessed March 17, 2015.

http://academic.research.microsoft.com/Publication/5912988. Hempling, Scott. “Chinook Plus -- Renewable Energy Prices in State-Level Feed-in Tariffs Federal Law Constraints

and Possible Solutions.” Accessed April 8, 2015. http://encore.colorado.edu/iii/encore/record/C__Rb6049127__Sfeedin%20tariffs__P0%2C1__Orightresult__U __X6?lang=eng&suite=cobalt.

Jenkins, Nathan. "Renewing the Push for Renewable Energy in Virginia « Appalachian Voices. "Appalachian Voices RSS. N.p., 24 Jan. 2013. Web. 07 Apr. 2015. Kutscher, C. “Chinook Library Catalog - ‘Renewable Portfolio Standards Colorado’ Search Results.” Accessed

March 12, 2015. http://libraries.colorado.edu/record=b7042806~S3. Kydes, Andy. “Impacts of a Renewable Portfolio Generation Standard on US Energy Markets.” Accessed April 9,

2015. http://www.sciencedirect.com/science/article/pii/S0301421506001169. Mahone, A. “Viewpoint: Renewable Portfolio Standards and Cost-Effective Energy-Efficiency Investment -

Environmental Sciences and Pollution Management - ProQuest.” Accessed March 12, 2015. http://www.sciencedirect.com/science/article/pii/S0301421508007258.

Moore, Jared. “Could Low Carbon Capacity Standards Be More Cost Effective at Reducing CO2 than Renewable Portfolio Standards?” Accessed April 9, 2015. http://www.sciencedirect.com/science/article/pii/S1876610214025983.

Namovicz, Christopher. “The Experience with Renewable Portfolio Standards in the United States.” Accessed

April 9, 2015. http://www.sciencedirect.com/science/article/pii/S104061900700036X. Palmer, Karen. “Cost-Effectiveness of Renewable Electricity Policies.” Accessed April 9, 2015.

http://www.sciencedirect.com/science/article/pii/S0140988305000885. Paul, Anthony.  “Federal Policies for Renewable Electricity: Impacts and Interactions.” Accessed April 9, 2015.

http://www.sciencedirect.com/science/article/pii/S0301421511000450. Rader, Nancy. “Efficiency and Sustainability in Restructured Electricity Markets: The Renewables Portfolio

Standard.” Accessed March 12, 2015. http://www.sciencedirect.com/science/article/pii/S1040619096802624. Schelly, Chelsea. “Implementing Renewable Energy Portfolio Standards: The Good, the Bad, and the Ugly in a

Two State Comparison.” Accessed March 12, 2015. http://www.sciencedirect.com/science/article/pii/S0301421513012056. Stockmayar, Gabriella. “Limiting the Costs of Renewable Portfolio Standards: A Review and Critique of Current

Methods.” Accessed April 9, 2015. http://www.sciencedirect.com/science/article/pii/S030142151100958X. Sun, Peng. “A Comparative Study of Feed-in Tariff and Renewable Portfolio Standard Policy in Renewable

Energy Industry.” Accessed March 12, 2015. http://www.sciencedirect.com/science/article/pii/S0960148114004868.

Udall, Thomas. “To Amend Title VI of the Public Utility Regulatory Policies Act of 1978 to Establish a Federal

Renewable Energy Portfolio Standard for Certain Retail Electric Utilities, and for Other Purposes.” Congressional Record. ProQuest, 2007. Web. 6 April. 2015.

Wiser, Ryan. “Chinook Library Catalog - ‘Renewable Portfolio Standards’ Search Results.” Accessed March 12,

2015. http://libraries.colorado.edu/record=b7795650~S3.