Ocean Energy

Ocean Energy

One of the ways to capture energy from the ocean is through temperature. Ocean thermal energy conversion (OTEC) is a renewable energy technology that uses the ocean’s temperature variations to create electricity. For those of us who have been in ocean waters, the temperature difference between the sun-warmed surface and a few meters below the surface is noticeable. Temperature differences increase with depth. OTEC is particularly viable for tropical regions where there is a 20 degrees Celsius difference or more between surface and deepwater temperatures.

An OTEC facility has three main phases. First, warm water is introduced into a closed loop system containing a low boiling point carrier liquid such as ammonia. The warm water vaporizes the ammonia, which then passes through an electricity-generating turbine. The vapor’s pressure is then dropped by a condenser connected to the inflow of cold seawater. The now liquid ammonia begins the energy cycle again by being reintroduced to warm water.

The upfront costs of an OTEC facility are substantial, especially compared to long-term maintenance costs of the facility. Cost effective strategies factor location and materials. Ideal sites involve deep ocean waters with nearby shorelines. The piping system to bring cold water up is often one of the most expensive aspects of the facility, but evolution of cheaper, lighter weight and more durable materials will bring these costs down. Additionally, implementers are trying to increase efficiency by using waste heat from industrial processes to increase ocean water temperature differences.

The U.S. government has varied in its funding of OTEC technologies. In the 1970s, funding was provided for research and development but this funding has decreased and today, there is no official subsidy program to finance start up costs. Without the government subsidies that other renewable energy technologies experience, it is difficult for OTEC facilities to gain traction as viable, widely implemented energy sources. In spite of the history, stakeholders are optimistic that rising energy costs, increased concern for global warming and political commitment for energy security will make OTEC commercialization an attractive energy option in the future.

References:

http://coastalmanagement.noaa.gov/otec/docs/oteconepage07202010.pdf

http://www.makai.com/e-otec-og.htm

http://coastalmanagement.noaa.gov/programs/otec.html

http://www.energyquest.ca.gov/story/chapter14.html

http://www.sciencedirect.com/science/article/pii/S0308597X11000972

 

 

Organic Farming: Energy Efficiency?

This past weekend, I went to Coyote Farms in Elgin, TX and got a tour of their farming operation. The farm primarily produces organic eggs and organic animal feed. Some of you may have seen their eggs in Austin stores; they are labeled as Jeremiah Cunnigham’s World’s Best Eggs. Coyote farms produces 100% organic products. Their vision is to revitalize middle income farming practices through sustainable faming techniques and humane treatment of animals. A significant portion of the farm’s business is derived from the organic feed. Coyote Farms is the only organic feed producer in Texas. All of their feed components are sourced in Texas and mixed on the farm. A significant portion of the tour was dedicated to explaining the feed production process. A mixture of wheat, soy, legumes and other grains comprise most feeds (a fraction of their feed is produced soy-free). Because of the nutritional variation of products, Coyote Farms regularly performs nutritional testing to ensure their feed maintains constant nutritional levels. Apparently, peas grown in west Texas can have different vitamin and caloric values than peas grown in east Texas due to geographic variations in soil, sun and rain, for example. The farm experiences high demands for their organic feed and they often struggle to have enough supply of raw feed components. The farm is hoping to promote more Texas farmers to produce organic grains. Coyote Farms believes that there is a greater demand for organic agricultural products than there is a supply.

While energy was not explicitly discussed on the farm tour, a couple of points about energy inputs and outputs came to my mind. The first relates to a comment from John, the tour guide. After explaining the complexities of combining grain and legume components to make feed, John said that the farm was interested in producing organic, nutritionally dense feed rather than large quantities of simple calorie dense feed, typically produced by conventional means. John followed up this comment by stating that because organic feed tends to be more nutritionally dense, farmers usually use less than they would conventional feed. He also said that livestock tends to be healthier on an organic diet therefore decreasing farmers’ cost of medicine. While John’s comments were anecdotal, the nutritional efficiency that he spoke of made me wonder how and if it translated to energy efficiency.  Since the raw materials for the feed come from all across Texas I wonder if the Texas environment is well suited for growing these items. Does the desire for “locally sources” trump environmental efficiency? In Dr. Webber’s lecture we learnt about the energy inefficiency that can result from growing food locally in un-ideal environments. When considering the environmental factors, the research reveals that there are numerous benefits to organic livestock and dairy production versus conventional rearing. Output comparisons show reveal slightly different results. With respect to organic feed for cows, for example, they produce less milk on average on organic feed than on conventional feed. This is probably due to higher volumes of feed given and that conventional feed tends to have higher protein ratios. In pig rearing, similar trends reveal that pigs on organic feed grow to smaller sizes on average than pigs fed conventional feed. In considering these differences however, it is important to note that we compare organic farming outputs to conventional industry standards, which in essence are inflated to above “natural” outputs for many of these animals. The conventional livestock industry has gone to great lengths to modify animals, living conditions and feed to increase yields. Thus, while organic production and feed may yield less output than conventional practices, a more holistic assessment must incorporate various factors including environmental impacts, treatment of animals and human health impacts resulting from consuming organic products. Coyote Farms is addressing all these factors and they are producing quality products whose market share, particularly in the Austin area, is growing at a fast pace.

Sources:

Blair, Robert. “Nutrition and Feeding of Organic Pigs”, 2007.

Sundrum, Albert. “Organic Livestock Farming: A Critical Review”. Livestock Production Science; January 2001.

http://coyotecreekfarm.org/

 

The Case for PACE

In the effort to slow global climate change, municipalities have been called the “first responders” with regards to increasing energy efficiency in buildings.  The building sector accounts for 72% of electricity use and 36% of greenhouse gas emissions [1].  Local municipalities have found it relatively simple to reduce the carbon footprint of new buildings by updating building codes to require more energy-efficient appliances, heating and cooling systems, and other features.  However, due to the long life cycle of existing buildings, more creative solutions have been developed to update existing buildings and reduce the up-front costs that must be paid by property owners. Developed at Cal-Berkeley and first implemented in Bay Area communities, financial mechanisms have been developed called Property Assessed Clean Energy (PACE) that address many of the challenges associated with improving the energy efficiency of residential and commercial buildings.

So what exactly is PACE? Local municipalities can create PACE programs that give loans to property owners to help fund energy-efficiency projects on their properties [2].  These projects must be attached to the property and usually include solar thermal and solar PV systems, efficient insulation, efficient doors and windows, some appliances, and some water-saving measures.  These improvements are designed to reduce energy demand, and the financing program allows the owners to receive a loan that is repaid over a typical period (20 years) as a property tax assessment.  The loan is attached to the property as a lien.  The improvements are then connected to a specific property instead of an individual like most loans and mortgages.  The up-front capital comes from a municipal program that is funded by municipal bonds.  Only the property owners that choose to utilize the program will pay higher property tax rates in order to repay the loans.  If property owners choose to sell the property, the costs of the improvements will then be paid in the same manner by the next owner [3].

One of the aims of this program is to combat the barrier of high up-front costs for property owners [4]. Using PACE encourages property owners to invest because they can begin to see immediate net energy savings long before their investments have been paid off.  In addition, their investment is not wasted if they choose to move.  Because the program is run by municipalities, the bonds that supply the program’s funding can secure low-interest rates.  In addition, municipalities can certify contractors as well as provide trusted information sources to interested citizens.  PACE programs in any community help to spur economic growth in that community.  The Brookings Institute estimates that every $4 million in PACE funds spent by property owners results in $ 10 million of economic output, $1 million in local, state, and federal tax revenue, and at least 60 jobs [5].  It is estimated that if 1% of the 75 million owner-occupied homes in the U.S. use PACE to invest an average of $20,000 each, 226,000 jobs will be created across the country.

For all of the benefits of PACE, there are several limitations. PACE financing only applies to improvements on the property, so energy-efficient appliances and lighting that property owners can move with them cannot be financed. In addition, lease property owners have little incentive to use PACE financing because energy-efficiency improvements reduce their tenants’ utility bills.  PACE programs in large urban centers also have difficulty catching on due to the presence large-scale residential buildings. In addition to these challenges, the Federal Housing Finance Agency (FHFA) has recently blocked scale-up of residential PACE programs.

In July 2010, the FHFA recommended to government housing finance arms Fannie Mae and Freddie Mac that they should not buy securitized mortgages that have PACE liens attached to them.  Because the PACE liens placed on properties take priority over mortgage liens, the FHFA stipulated that PACE financing creates significant risks for lenders and mortgage holders. These are legitimate concerns for the massive housing financing arms; unfortunately, these moves have derailed a promising solution to overcoming clean energy barriers [6].  The state of California has led the charge in the courts against the FHFA, but many of communities in the 28 states that have approved the creation of municipal PACE programs have put program development on hold until the FHFA approves properties with PACE liens.

Despite all of the setbacks for PACE, the programs are beginning to flourish in parts of California such as Sacramento and the Bay Area.  In addition, there is bipartisan support in Congress for PACE programs as evidenced by $150 million of federal funds provided by the American Recovery Act and HR2599, a bill introduced in July 2011 that would prevent the FHFA from contravening in local and state PACE programs. While there is great potential for PACE programs to further develop, the financial and policy setbacks must be addressed by Congress, President Obama, financial agencies and state leaders.  PACE programs have been shown as a great way to reduce energy demand, pass savings on to property owners, create jobs, and develop clean energy infrastructure.

Sources:

[1] http://rael.berkeley.edu/sites/default/files/berkeleysolar/HowTo.pdf

[2] http://www.statutes.legis.state.tx.us/Docs/LG/htm/LG.376.htm#376.001

[3] http://pacenow.org/about-pace/what-is-pace/.

[4] http://www.dsireusa.org/incentives/incentive.cfm?Incentive_Code=TX81F&re=1&ee=1

[5] http://www.brookings.edu/~/media/Research/Files/Papers/2012/11/13%20federalism/13%20housing%20energy%20efficiency.pdf

[6] http://latimesblogs.latimes.com/money_co/2010/07/fannie-freddie-freeze-pace-energyefficiency-retrofit-financing-programs.html

The Big Picture: The Impact Our Relationship to Energy Will Have in the Future

Many scholars and economists around the world have come to a simple conclusion; as global climate change threatens our planet and our way of life, human activity regarding energy development and consumption will play a crucial role in the solution (or lack thereof). Tom Dietz, professor of Sociology and Environmental Policy at the Michigan State University, speaks to the fact that a solution to this problem will be anthropomorphic, as is the very problem we aim to solve.[1] Specifically, Mr. Dietz analyzes the behavioral changes that would be necessary for humans to make in order to enact significant change and improvement for our climate.  He observes what incentives will compel different groups to change their consumption patterns, and even goes as far as to measure how these changes are reflected, or ignored, in our political system.

Mr. Dietz, like David Victor, professor at the School of International Relations and Pacific Studies at UC San Diego, has come to some alarming conclusions. In measuring how humans change behavior based on their understanding of the negative impacts that climate change will have on their lives, he has found that their willingness to change is generally as expansive as their willingness to save money. In other words, behavioral change regarding climate change is not a top priority for most, even those who understand the negatives impacts that their emissions and consumption have on the planet.  Similarly, Victor describes the gridlock in international politics surrounding the climate change issue. Gridlock in the United Nations has become status quo, as many nations set goals that they cannot achieve or that do not amount to meaningful CO2 reductions in the first place. Mr. Victor eloquently describes how international negotiations have failed to look at this issue with the complexity that it deserves, and that a unanimous agreement for worldwide CO2 reduction at the levels necessary to significantly stem the damages from climate change is unlikely to ever emerge from this body.[2]

Climate change is a result of many human activities, while CO2 emissions receive the lions share of publicity, other contributing factors should be taken into account. Mr. Victor points to the fact that the political barriers to making headway on CO2 reductions and other major contributing factors to climate change could be mitigated if governments were to establish precedence for successful regulation first. He gives the example of how many countries could lower ash pollutants from power plants without great difficulty, thus solidifying political support for climate initiatives as well as demonstrating immediate benefits to these actions (reductions in ash contamination can result in better air quality in the short term).  Sound policy on the nation state level, as well as bilateral agreements between large polluters (US and China) could have major impacts on CO2 reduction, regardless of whether international CO2 standards have been established.

Whether people will change their behavior depends on several factors; research into how providing better information to consumers will help them curb energy consumption is getting attention. I am working on a project to observe changes in lower income households as they use energy-monitoring units to monitor their consumption. Whether this information will help consumers lower their consumption to a point that will benefit the environment, or at all, remains to be seen. Nevertheless, this research helps scientists observe the relationship that man has with energy – a relationship that will define our future, and may help bridge the gap between those who believe that technology is an end all be all solution to our problem and those who do not see any solution to our current state of affairs.

---

[1] http://behavioralwedge.msu.edu/

[2] http://www.guardian.co.uk/environment/2011/apr/04/un-climate-change

New Process Develops Additional Use for Waste Sulfur Stream

Sulfur is a common byproduct of the oil refining process: hydrodesulfurization produces around 0.5 lb of sulfur for every 19 gallons of gasoline that is processed [1,2]. A team led by professor Jeffrey Pyun and Ph.D. student Jared Griebel at the University of Arizona have developed a new process to create a useful polymer from this waste stream [1]. 

Sulfur Polymer Sample and Elemental Sulfur [1]

 
A traditional use for elemental sulfur has been as feedstock for sulfuric acid [2]. However, recently, sulfur production is far outpacing market demand, and refineries are developing huge stockpiles of the material [1]. The new polymer developed at UA has potential uses as both a structural plastic and as a better constituent material in the Li-S rechargeable battery chemistry [1]. For these batteries, compared to traditional materials, the new polymer demonstrates improved properties of specific capacity and capacity retention [2]. The team, along with other co-authors, published their results in Nature Chemistry, and three companies are currently investigating commercial applications for the material [2,3].

[1] www.dailytech.com
[2] www.nature.com 
[3] azstarnet.com

Increasing Solar Efficiency by using nanotechnology application

Solar energy has been a crucial research field for many years; unfortunately, due to low conversion efficiency, which the scientists have been trying to deal with, the maximum efficiency has been around 20-30 percent.Recently, advances in nanotechnology is going to lead to a higher efficiency and lower costs which will tremendous impact on solar sector. According to the US Department of Energy’s National Renewable Energy Laboratory(NREL), “the nanotechnology research on solar energy will provide an answer to the efficiency problem, boosting the ability to convert sunlight into power by using less material [1].

Fig1 .Nanotechnology application on solar cell

Recent study on solar cell from Princeton University showed that by devising a nanostructured “sandwich” of metal and plastic has been increasing triple the efficiency of solar cells. This invention is called plasmodic cavity with subwavelength hole array.It basically consists of a thin strap of plastic sandwiches between the layers.Moreover , Northwestern University introduced a method to increase the efficiency such that it uses carbon-based materials rather than silicon crystals; where the light first enters 100 nm thick leyer with an complex  geometric pattern. These two recent study has been developing by the researches to provide a sustainable for the long term.

Fig2 . Complex nano-patterning on solar cell

Consequently, the effect on solar industry on energy sector is tremendous. For instance, 8 kwh/day radiation is received in Arizona and Texas which is a very important number.Hence, when the efficiency problem is solved with the ongoing researches, the sector will make a huge profit with lower manufacturing costs [2]. Also, this will be renewable and environmentally friendly which will bring  great and new advantages for everybody.

 

Source:US Dep. of Energy

References

[1] http://news.nationalgeographic.com/news/energy/2013/04/130429-nanotechnology-solar-energy-efficiency/

[2]http://energy.gov/science-innovation/energy-sources/renewable-energy/solar

 

Using Renewable Energy to Reduce Poverty

There are currently around 1.3 billion people, approximately 20% of the world’s population, that lack access to electricity. Most of these people live in poverty and rely extensively on biomass and fossil fuels for heating and lighting. The United Nations has set a Millennium Development Goal to achieve universal electricity access by 2030. While this is a hopeful goal, it is certainly within reach. [1]

 

Electricity is tied with wealth and quality of life. Impoverished countries that lack electricity access must rely heavily on subsidized fossil fuels in order to heat and light their homes. Also, the poorest countries in the world typically import most or all of their fossil fuels. According to one study done by The Worldwatch Institute, “ of the 47 poorest countries, 38 are net importers of oil, and 25 import all of their oil.” [2]

 

This heavy dependence on fossil fuels creates a strain on the economy of both the governments and the people in these countries. Governments must constantly be wary of unstable oil prices, and money that could be better spent on education or healthcare must go into these subsidies in order to provide a consistent low price for the people. Many different policy measures have been tried to help this system, but according to the IEA, “Only 8% of the subsidies to fossil-fuel consumption in 2010 reached the poorest 20% of the population.” [3] This dependency is a vicious cycle: one that could be broken by introducing renewable energy.

 

Renewables provide several benefits for people in poverty. For one, new jobs would be created inside the countries installing and maintaining the systems. By bringing the energy sector within countries, governments will no longer be reliant on imports and will be able to redirect funds into social programs that will better benefit the poor. Renewables such as solar panels could be easily implemented in rural areas without the need to invest in expansive transmission lines. Essentially, renewables could easily bring electricity to impoverished people in a very short amount of time. Businesses could thrive by being able to stay open longer, and children could spend more time studying rather than collecting fuel to cook with. [4]

 

An Indian woman’s lighted home from solar powered LEDs [5]

 

 

 

[1] -http://www.forbes.com/sites/mahaatal/2012/09/26/sustainable-energy-for-all-how-to-fight-poverty-and-climate-change/

[2] –http://www.worldwatch.org/brain/media/pdf/pubs/ren21/ren21-1.pdf

[3] – http://www.worldenergyoutlook.org/media/weowebsite/2011/executive_summary.pdf

[4] – http://www.sarpn.org/genderenergy/resources/cecelski/energypovertygender.pdf

[5] – http://www.guardian.co.uk/global-development/poverty-matters/2013/mar/06/india-solar-electricity

 

 

 

 

 

Fusion in the Not-So-Distant Future

Using fusion reactors in place of fission reactors is not a new idea, but the technology has always seemed so far away. However, according to research done by the International Thermonuclear Experimental Reactor (ITER), construction of the world’s largest experimental tokamak nuclear fusion reactor will be completed by 2020. The ITER consists of seven countries: the European Union (EU), Japan, India, China, South Korea, Russia, and the United States. If this reactor is successful, it will pave the way for eventually replacing fission power plants with fusion power plants.

 The difference between fusion and fission is that fusion takes heavy atoms (uranium 235 is the most commonly used isotope in industry) and splits them into smaller atoms, producing energy. The heat from this energy is used to generate steam from water to turn a turbine, which powers a generator to produce electricity. Fusion, on the other hand, takes two smaller isotopes (such as deuterium and tritium, which are isotopes of hydrogen) and fuses them together to make a heavier atom (such as helium). Like fusion, the energy from this reaction powers a steam-turbine system to generate electricity.

So what is wrong with our fission power plants that we even have to think about fusion? Fission reactors are usually about 30% to 45% efficient. As Dr. Webber has discussed in class, fission nuclear power plants also generate some very dangerous radioactive waste that we do not really know how to deal with yet. Fusion is a very attractive alternative because it produces no carbon dioxide and is expected to produce 10 times the amount of energy that is required to power the reaction [1]. One of the most attractive aspects of fusion, though, is that it produces a minimal amount of radioactive waste. This is because the deuterium and tritium isotopes chosen for the fusion reaction in the to-be-built reactor do not have a long term legacy of radioactive waste. Not to mention, these hydrogen isotopes are naturally abundant in Earth’s oceans [2]. We would not have to go digging around, looking for fuel for fission anymore.

 If fission is so great, why have we not started using it by now? The fusion reaction is extremely hard to contain. Fission is relatively easy to induce compared to fusion. In order to make two atoms fuse together, you need to give the atoms a great amount of potential and kinetic energy to want to even go near each other, let alone fuse. In fact, you would need to heat the gases consisting of the hydrogen isotopes to temperatures greater than 100 million degrees Celsius. That is about 10 times the temperature at the center of the sun! Once fused together, the fuel enters the fourth state of matter: plasma. Needless to say, no material on Earth is able to withstand the high temperatures of plasma [2].

 The solution for this is to exploit the physical properties of plasma itself. Plasma consists of charged particles that can be directed and confined by magnetic forces. The particles in the plasma will follow magnetic field lines. Magnetic fields are not affected by heat. ITER’s tokamak reactor will utilize a donut-shaped reactor chamber, called a torus. This torus will use magnetic fields to shape the plasma into a ring-shape, continually spinning the plasma in the torus chamber and preventing the fuel from touching the container walls [3]. When I think of magnetic fields, I automatically imagine refrigerator magnets. So to me, thinking that plasma can be contained by something as small (or should I say as strong?) as a magnetic field is somewhat scary. Of course, the magnetic fields that the torus will have will be much stronger than the refrigerator magnets I am thinking of, but the science is still unfathomable to me, as I am sure it is for many other people as well.

 Many people are also concerned about the safety of these fusion reactors. At first I thought that if the fusion reaction somehow escapes from its containment unit that it would just go on to consume everything in its path for the reaction, and the reaction would go out of control. However, Aris Apollonatos, who is the communications leader for the EU branch of the ITER project, says that there is no risk of meltdown or runaway reactions because the plasma will cool itself and stop the process if anything should go wrong [1]. While this makes sense to me, I feel that it would still take a long time for the plasma to cool down from such high temperatures before being safe enough to be around. Though, I am pretty sure that they will have adequate safety measures in place in case anything goes wrong. This reactor is still highly experimental, so they have to be extremely cautious.

 Overall, fusion is definitely a promising alternative source of energy to what we have available now. The technology now has made fusion reactors a not-so-distant possibility. I am interested in seeing the result of ITER’s fusion reactor and what it will do for the world’s energy landscape.

 

Resources:

1. http://www.smartplanet.com/blog/global-observer/building-the-worlds-largest-nuclear-fusion-reactor/10646
2. http://www.bbc.co.uk/news/science-environment-11541383
3. http://www.iter.org/sci/plasmaconfinement

Belgium’s Battery Island

One of the largest hurdles facing renewable energy is intermittency.  Renewable energy is often available during off-peak hours or only during parts of the day.  Both situations seem to require some sort of storage in order to balance the load and provide a continual electricity supply. 

Belgium has side-stepped the battery issue in their plans for a pump-storage “battery” island near their offshore wind farms in the North Sea.  The island is planned to be 3 km in diameter and will be located around 4 km off the coast of West Flanders.  The project is slated to be completed in the next five years and will consist of a horseshoe-shaped island with a large central water reservoir.  Upon completion, the island would use excess electricity generated from the wind farm to pump water out of the reservoir.  The energy is recovered again later when water is released back into the reservoir through a hydro power plant at the end of one of the horseshoe legs.  The pump-storage technique is traditionally used in mountainous regions where water is pumped to higher elevations when electricity is cheaper and then released during peak demand.  The Belgian battery island is an innovative display of this traditional technology.

The integration of this technique with renewable offshore energy is a very interesting solution to the dilemma of renewable intermittency.  Belgium is phasing out its nuclear program and replacing most of that electricity generation with wind power.  In 2011, the country had just 1,078 MW of wind power connected to the grid, but production is expected to expand to over 4,000 MW by the year 2020 generating a very real need for some sort of battery to help balance load.  The creation of a pump-storage island battery is a very innovative solution to their intermittency dilemma.

 

An Overview of Austin Energy’s New Smart Thermostat Program

In late April Austin Energy announced that customers participating in a new smart thermostat program would be eligible to receive an $85 rebate on qualifying thermostats. The new rebate program is similar to the Power Saver program, which provided free programmable thermostats to customers in exchange for allowing Austin Energy to remotely cycle the thermostats during periods of peak electricity demand.

One of the goals of the new program is to further reduce peak demand during the summer months, which Austin Energy said has already been reduced by up to 40 megawatts through the free thermostat program [1]. In exchange for the $85 rebate, Austin Energy retains the ability to remotely cycle on and off the new smart thermostats in participating households from 4 p.m. to 6 p.m. for 10-15 days during the hottest months.

The program covers three smart thermostats, including options from Nest, Filtrete and Ecobee. Below is a cost comparison chart of the different thermostats based on the retail prices on www.amazon.com, as of May 4, 2013 [2].

These programmable smart thermostats allow consumers to access and manage home heating and cooling controls from a computer or mobile device, although certain models require additional equipment in order to obtain these benefits. According Austin Energy, the thermostats can help households reduce cooling and heating bills by up to 20 percent. Some research has also shown that smart thermostats can improve overall temperature control and extend the lifetime of heating and cooling equipment in the home [3]

However, other studies have shown that installing smart thermostats does not lead to consumer savings, particularly for households that are already energy conscious consumers [4]. Given that Austin Energy consumers must opt-in to the new smart thermostat rebate program—and that some of those consumers are already energy conscious consumers—it may not lead to significant savings for most households.

Sources

[1] Austin Energy. Accessed May 2, 2013. http://www.austinenergy.com/About%20Us/Newsroom/Press%20Releases/2013/smartThermostatProgram.htm

[2] Austin Energy.

[3] Saha, A., M. Kuzlu, and M. Pipattanasomporn. “Demonstration of a home energy management system with smart thermostat control.” In Innovative Smart Grid Technologies (ISGT), 2013 IEEE PES, pp. 1-8. IEEE, 2013.

[4] Surles, William, and Gregor P. Henze. “Evaluation of automatic priced based thermostat control for peak energy reduction under residential time-of-use utility tariffs.” Energy and Buildings 49 (2012): 99-108.