1

BRIGHTSOURCE ENERGY FAQ’s

COMPANY OVERVIEW When was the company founded? BrightSource Energy was founded in 2006. Where is the company located? BrightSource is headquartered in Oakland, Calif. with operations in the United States, China, Europe, Israel and South Africa. How is BrightSource Energy financed? Who are BrightSource Energy’s investors? To date, BrightSource Energy has raised more than $615 million in private financing from blue chip investors including VantagePoint Capital Partners, Alstom, Morgan Stanley, Google.org, BP Alternative Energy, StatoilHydro Ventures, Chevron Technology Ventures, Black River, Draper Fisher Jurvetson, and DBL Investors (a spin-off from JP Morgan), and the California State Teachers’ Retirement System. BUSINESS OVERVIEW What does BrightSource do? BrightSource Energy designs, develops and deploys concentrating solar thermal technology to produce high-value steam for electric power, petroleum and industrial-process markets worldwide. BrightSource combines breakthrough technology with world-class solar power plant design capabilities to generate clean energy reliably and responsibly. BrightSource’s solar thermal systems are designed to minimize impact to the environment and help customers reduce their dependence on fossil fuels. What markets does BrightSource compete in? Our primary market is electricity generation. Our solar steam technology can also be used in petroleum and industrial applications, like enhanced oil recovery and mining, to displace fossil fuels. Where has BrightSource’s technology been deployed? BrightSource’s technology is featured in the following facilities:

Solar Development Energy Center (SEDC), BrightSource Energy’s 6 megawatt thermal solar demonstration facility in Rotem, Israel. Fully operational since 2008, the facility is used to test equipment, materials and procedures as well as construction and operating methods.

Chevron/BrightSource Solar-to-Steam Demonstration Facility located in Coalinga, Calif. The 29 megawatts thermal solar-to-steam facility began operation in 2011 to support enhanced oil recovery efforts at Chevron’s oil field.

Ivanpah Solar Electric Generating System, a 377 megawatt (net) solar thermal facility located in California’s Mojave Desert. The project began commercial operation in 2013, delivering power to PG&E and Southern California Edison.

Ashalim Thermal Solar Power Station, a 121 megawatt facility to be located in Israel’s Negev desert. Construction has begun and the project is scheduled to be completed in early 2017.

2

TECHNOLOGY How does BrightSource Energy’s technology work? BrightSource Energy’s proven solar thermal tower technology produces electricity the same way as fossil fuel power plants – by creating high-temperature steam to turn a conventional turbine. However, instead of using fossil fuels to create the steam, BrightSource uses the sun. At the heart of BrightSource’s proprietary solar thermal system is a state-of-the-art solar field design, optimization software and a control system that allow for the creation of high-temperature steam. Thousands of software-controlled mirrors track the sun in two dimensions and reflect the sunlight to a boiler that sits atop a tower. When the concentrated sunlight strikes the solar receiver, it heats water to create superheated steam. The steam is either piped from the boiler to a conventional steam turbine to produce electricity, where transmission lines will carry the power to homes and businesses, or the steam is used in industrial process applications such as thermal enhanced oil recovery (EOR). By integrating conventional power block components, such as turbines, with our proprietary technology and state-of-the-art solar field design, electric power plants using our systems can deliver cost-competitive, reliable and clean power when needed most. We can also integrate proven molten salt storage or hybridize with a fossil fuel, further increasing output and reliability, and significantly reducing energy costs. Where does BrightSource test its technology? BrightSource’s technology has been operating at the company’s demonstration facility, the Solar Energy Development Center (SEDC) since June 2008. The SEDC is the only known solar thermal facility in the world to have directly produced superheated steam at over 540°C on a continuous basis through technology that is used on a utility scale. With more than six years of operations, the 6MWth facility provides unmatched operational and production data from its 1,641 heliostats, 12,000 square meters (130,000 square feet) of reflecting area and 60-meter (200 foot) receiver tower. What are the basic advantages of concentrating solar power technology? Concentrating solar thermal power (CSP) technology helps utilities and grid operators address integration challenges by delivering a more firm, reliable and controllable renewable power source compared to other variable generation resources. Because of the plant’s synchronous steam turbine generator, CSP provides important reliability benefits, such as reactive power support, dynamic voltage support, voltage control and some degree of inertia response. CSP technology compensates for solar resource variability through the ability to increase or decrease the number of mirrors focusing on the receiver. This capability adds stability to the generation profile by allowing facility operators to shape the profile as system needs change. CSP’s operational attributes can also reduce the need for back-up fossil fuel generation to meet grid reliability requirements. BrightSource’s CSP systems can also use a small amount of natural gas to achieve quicker morning startup and longer solar generation at the end of each day as well as to produce a less variable, more reliable power output compared to other solar technologies.

3

Grid Reliability Services CSP plants using synchronous generators provide the same types of support for the reliable operation of the transmission system as conventional synchronous generators. As a result, CSP plants provide numerous important reliability services, such as reactive power and voltage support, primary and secondary frequency control and some degree of inertia response. These attributes promote reliable operation of the transmission grid by controlling voltage and frequency within an acceptable band. The primary grid reliability benefits of CSP are described in more detail below. Reactive Power and Voltage Support The power system requires reactive power from generators, synchronous condensers, capacitors or other voltage support devices to support power transfer and maintain operating voltage levels under both normal and emergency conditions. On the one hand, inadequate reactive power can result in power transfer reductions and voltage collapse and thus could lead to widespread blackouts. On the other hand, the over-supply of reactive power can increase voltage at points in the system to very high levels and create an unintentional electrical arc that can damage the grid and customer equipment and create unsafe operating conditions. Power system voltages are affected by a variety of factors, including customer loads, the distance power is transmitted to the loads, and the amount of loading on the power lines. Because the power system conditions are variable and constantly changing, the amount of reactive power needed at various points in the transmission system to maintain adequate voltage is also variable and constantly changing. As such, the power system must include devices capable of constantly and automatically adjusting (injecting and withdrawing) the reactive power supply at specific points in the system. The synchronous generators in BrightSource’s plants are this type of device – they are capable of automatically adjusting the reactive power supply through the exciter/automatic voltage regulator control under normal (all facilities in-service) conditions and under contingency conditions. During and after sudden changes in grid conditions (e.g., during a fault or following the outage of transmission facilities), fast and automatic injecting and withdrawing of reactive power is crucial to maintain voltage stability and reliable system operations. In addition, if the system voltage begins to collapse, fast automatic increases in reactive power output are required to raise the voltage and prevent a collapse that could cause a blackout. Synchronous generators are capable of providing this grid reliability service and do so in a manner more effectively than other devices such as Static VAR Compensators (SVC) or Static Synchronous Compensators (STATCOM). The reactive power provided by SVC and STATCOM decreases as the voltage drops, making them less effective as the voltage collapses, exactly when reactive power is needed. Synchronous generators will help prevent excessive voltage drop by providing automatic and continuously the same amount of reactive power independent of system voltage levels; thus, better supporting the transmission system as voltage decreases and thus helping to prevent voltage collapse. Frequency Control To maintain system frequency in an acceptable band, the system needs to hold resources in reserve to provide frequency control. This is accomplished in two ways – primary frequency control and secondary frequency control. Primary frequency control is the ability to automatically and autonomously adjust

4

output rapidly (within seconds) after the sudden outage of other generators. Secondary frequency control refers to the ability to respond within minutes to changes in system frequency through Automatic Generation Control (AGC) under normal operating conditions. Both primary and secondary frequency control are critical to maintaining overall grid stability and can be provided by synchronous generators. Moreover, since the output of PV is intermittent and PV does not intrinsically offer frequency control services, synchronous generators will serve to promote PV integration by providing the option of a clean source of frequency control needed to maintain grid reliability. Inertia Response Inertia on the grid is created by the energy stored in the rotating mass of conventional power plants. Inertia acts as a buffer that helps suppress frequency deviation due to various changes in the system. During and after the sudden loss of a transmission facility or a generator, inertia helps arrest the frequency decay (or overshoot) and allows time for generators in the system to stabilize the system. Since they provide rotating mass, inertia response is provided by the synchronous generators.

Solar Field Multiple and System Inertia

Solar thermal projects typically have collector field mirror areas that allow, during periods of high radiation and the hours near solar noon, more thermal energy collection than can be accommodated by the solar receiver and the steam turbine-generator, commonly referred to as the “solar field multiple.” This combination allows the solar receiver and the steam turbine-generator to operate at maximum continuous duty during the mid-morning hours, the hours near noon, and the mid-afternoon hours. In effect, solar energy collection is reduced in the hours near noon to allow the steam turbine-generator to operate at maximum continuous duty during the shoulder periods of the day. The ability of the solar field to supply thermal power to the receiver in excess of the receiver rating also allows the steam turbine-generator to operate at high outputs during partially cloudy periods.

In addition, solar thermal tower technology, compared to non-thermal solar technologies, possesses an inherent system thermal inertia that results in less immediate and less volatile effects of reduced solar radiation on the electric output of the plant. At the beginning of such a weather event, a significant quantity of saturated water exists in the steam drum of the receiver. Further, the temperatures of the superheater section of the receiver, and the main steam descending piping to the steam turbine, are equal to the normal steam turbine inlet temperature. For the first few minutes of a cloud event, thermal energy can be withdrawn from the steam drum, the superheater section of the receiver, and the descending piping to maintain the output of the steam turbine at a level which is greater than the solar radiation would normally allow. Under certain conditions, the reduction in the electric output can also be minimized by taking advantage of the excess thermal energy capacity of the collector field, as noted above. Controllability Concentrating solar thermal tower technology has the particular ability to control the number of heliostats focusing on the receiver to account for variability of insolation in time of day and season, further stabilizing and shaping a plant’s generation profile to meet power system needs. BrightSource’s CSP plants can decrease or “turn down” excess mirrors when available solar energy is greater than can be absorbed by the receiver system and converted to electricity by the turbine. Similarly, toward the end of the day or during times of lesser insolation (e.g., winter), a BrightSource plant can increase the

5

number of heliostats focused on the receiver to increase production and extend the generating day. These capabilities have the effect of reducing output variability. Over the long term, one of the compelling attributes of solar thermal power tower technologies is its natural synergy with thermal energy storage, which will provide valuable, clean grid reliability services, such as load following and spinning reserves. As described above, BrightSource can design plants to accommodate the addition of a thermal energy storage system. Increased Solar Energy and Reduced Variability from Natural Gas BrightSource’s CSP plants can be equipped with auxiliary gas boilers. These boilers provide several benefits to the plants, including increased renewable energy production and reduced variability of facility output. The auxiliary boilers are used to aid in system start-up, re-startup, and shutdown. By pre-heating portions of the solar receiver, the time to reach initial synchronization and solar electricity generation is accelerated. At the end of each day, generation can also be extended after which a minimal amount of gas-fired steam is used to control safe system cool down. In addition, during periods of transient cloud cover, the boilers can reduce the frequency and magnitude of facility output fluctuations that would otherwise need to be balanced by offsite, conventional power sources. In markets where efficient uses of natural gas integrated with a primary renewable generating resource are supported, a BrightSource CSP plant can supplement its natural gas operations. Even without, auxiliary gas boilers increase the amount of renewable energy on the grid and mitigate imbalances on the system. Transmission Reliability and Utilization Benefits As discussed above, synchronous generators can increase the reliability of a system by providing voltage control and inertia response due to the transient and post-transient stability benefits of these generators. The practical effect is that the transfer capability, or maximum line loading, of a transmission corridor can be greater in scenarios where synchronous generators, such as a CSP plant, and asynchronous generators, such as wind or solar PV, are both interconnected, as compared to a corridor with only asynchronous generators.1 Solar thermal technology assists utilities and grid operators in addressing integration challenges by delivering a firmer, more reliable, and more controllable renewable power source. CSP promotes broader integration and higher penetration of renewable resources by means of its synchronous generator, providing significant benefits such as grid reliability services, including reactive power, voltage support, frequency control, inertia response, and controllability.

Do towers have a cost/performance advantage over troughs?

Yes. The cost/performance advantage of tower systems is based on five key contributing factors:

More efficient production of steam from solar radiation due to two-axis tracking

More efficient generation of electricity from steam due to higher temperature steam production

Less ‘parasitic’ energy usage for plant operation due to reduced movement of thermal mass

Higher capacity factor – more megawatt hours produced per megawatt of installed power equipment

1 These benefits of synchronous generation generally exist where the transfer capability is limited by transient or post-transient stability constraints, rather than by thermal overload constraints.

6

Lower capital costs due to commodity-based inputs, no concrete foundations, and fewer pipes and cabling

How does a tower system produce steam more efficiently? Parabolic trough systems lose a relatively large proportion of heat, with about two-thirds of the losses occurring at the heat-collecting pipes in the troughs themselves and the remainder in the long pipes distributing the oil throughout the solar field. More energy is lost when reflected sunlight must pass through an evacuated glass tube in order to reach the heat-collecting pipe.

Tower systems have much lower heat losses because their heat-collecting pipes are concentrated in the receiver and not dispersed around the solar field.

Other factors are related to the geometry of the mirrors and their targets. For example, the mirrors in a tower system receive sunlight at a more advantageous angle than parabolic trough mirrors because they track the sun on two axes (i.e., in three dimensions) rather than on only one axis. The tracking advantage is particularly important when the sun is relatively low in the sky, such as in winter, or even in the early and late daylight hours at other times of the year. This means that a larger proportion of sunlight is reflected and ultimately utilized for electricity on a yearly basis.

How does a solar power tower system work and how is it different from parabolic trough systems? In a solar power tower system, computer-controlled mirrors track the position of the sun to reflect light onto a ‘central receiver’ or boiler sitting atop a tower. The boiler, containing water, is designed to be heated from the outside to produce superheated pressurized steam. The steam is then transported to a traditional steam turbine generator to produce electricity.

By contrast, parabolic trough systems use synthetic oil as an intermediate ‘heat-transfer fluid’ to absorb heat, which is then pumped through heat-collecting pipes mounted in the focus of parabolic trough-shaped mirrors. The pipes pass through a heat exchanger to generate steam, which drives a turbine generator to produce electricity.

How does the “capacity factor” make tower systems more economical? The capacity factor of a power plant is simply the number of hours of electricity it produces divided by the number of hours in a year.

During the winter, the poor angle of the sun onto horizontal troughs lowers system performance. But because the tower’s solar field can provide adequate electricity throughout the year, towers have a higher capacity factor.

Furthermore, a tower system can be designed to work at peak output levels for more hours over the course of the year, simply by adding inexpensive heliostats to an existing array of tower, receiver and power equipment. In contrast, the investment in trough plants is more evenly distributed throughout the solar field, and the raising of capacity factor is far more costly.

Why is generation of electricity from steam more efficient in a tower system? New generations of turbines can convert supercritical steam to electricity at efficiencies of more than 50%. BrightSource’s tower systems take advantage of the most efficient steam turbine generators, and the

7

company’s initial projects in California are rated at 540°C to 560°C and 140 to 160 bar with a net cycle efficiency of 40%. Future projects are planned to operate in the supercritical range of temperatures and pressures, with steam-to-electricity efficiency reaching 50%.

Trough systems, on the other hand, cannot make use of the same advances in turbine technology to increase the efficiency of electricity generation because the synthetic oils used for heat collection are limited to temperatures of about 390°C. Based on currently available information, turbines serving parabolic trough systems are generally around 36% efficient.

What is ‘parasitic’ energy usage and why do tower systems use less?

Parasitic energy is how much electricity the plant itself uses. For example, the pumps and motors of a solar field or receiver are examples of parasitic energy. The biggest use of parasitic energy in a parabolic trough plant is to pump the synthetic oil throughout the heat-collecting pipes throughout the field.

Tower systems avoid this costly expenditure of energy simply by not circulating fluid – water – in the solar field. The water/steam circulation pump in a central receiver requires far less electricity, and as a result total parasitic energy usage in a tower system is at least 50% less than in a comparable trough plant.

Typical parasitic energy values (including all solar field and heat exchange systems, the power block and balance of plant) are 12% to 14% of electricity produced for parabolic trough systems and 5% to 6% for a solar power tower plant.

How do the capital costs of towers and troughs compare? Towers have a unit capital cost advantage over troughs, which can be broken down into four distinct elements:

Glass: Flat glass mirrors are less expensive than curved glass mirrors. Structural steel: Tower heliostats are mounted singly or in pairs, creating a low wind load and therefore

requiring far less structural steel per square meter of mirror. Pipes: A tower system contains far fewer heat-collecting pipes in its boiler because of the higher sunlight

concentration ratios. Furthermore, tower piping is installed only at the central tower and not distributed throughout the field. In addition, trough systems require kilometers of header pipes for distribution of cold and hot oil to and from the working collector assemblies.

Civil works: Trough assemblies require sizable concrete foundations, and trenching and cabling throughout the solar field to bring power to the drive motors. The compact heliostats in a BrightSource tower system do not require foundations and use minimal cabling.

Why are power tower systems easier to implement than parabolic trough systems?

First, tower technology has surpassed solar plant topographic limitations: trough systems require extremely flat terrain with grades limited to <1%, while tower systems can be sited on terrain with grades of up to 5%. Second, tower technology does not face as many barriers in terms of field equipment. There are fewer manufacturers of curved glass appropriate for trough mirrors than manufacturers of simple flat glass mirrors. Furthermore, there are, at present, only two manufacturers of the specialized heat-collecting pipes used in parabolic trough systems.

8

Third, the potential adverse environmental impacts of trough systems often require more intensive environmental scrutiny and longer permitting processes. What is the history of the power tower technology? In the 1970’s Sandia National Laboratories in Albuquerque, New Mexico studied the power tower concept and proposed a test facility to investigate the concept and qualify components and systems for larger-scale evaluation at a pilot plant. As a result, the National Solar Thermal Test Facility (NSTTF) was built at Sandia in 1976. At NSTTF, 222 computer-controlled heliostats directed the sun into any of four test bays on a 205-foot (63-meter) tower to produce a total thermal capacity of 5 megawatts. The tower technology was first developed and made operational for electricity production in 1982 by the U.S. Department of Energy (U.S. DOE) working with an industry consortium to build a 10 megawatt project, known as Solar One, in Barstow, California. Solar One produced over 38 million kilowatt-hours of electricity during its operation from 1982 to 1988. Between 1992 and 1999, Bechtel acted as program manager for U.S. DOE on the Solar Two project that enlarged and retrofitted Solar One to use molten salt for heat transfer and thermal storage. During its operational period from April 1996 to April 1999, Solar Two successfully demonstrated efficient collection of solar energy and dispatch of electricity, including the ability to routinely produce electricity during cloudy weather and at night. In one demonstration, it delivered power to the grid for 153 straight hours (nearly a full week) before extended cloudy weather interrupted 24 hours per day operation. More recently, the first commercial power tower – an 11 megawatt plant known as PS-10, was commissioned near Seville, Spain in March 2007. A 20 megawatt project known as PS-20 was completed adjacent to PS-10 in April 2009. In 2011, the 20 megawatt Gemasolar project went live with up to 24 hours of solar power production. BrightSource also completed its demonstration facility, the Solar Energy Development Center (“SEDC”) in June 2008. The SEDC is the only known solar thermal facility in the world to have directly produced superheated steam at over 540°C on a continuous basis through technology that will be used on a utility scale. BrightSource’s technology is also being used in a commercial enhanced oil recovery facility owned by Chevron in Coalinga, California. The plant has been operating since October 2011. STORAGE How Does BrightSource SolarPLUSTM plant with storage work? BrightSource’s SolarPLUSTM plant combines BrightSource’s high-efficiency solar thermal system with a proven two-tank molten salt storage medium. A traditional BrightSource solar thermal system uses a field of software-controlled mirrors called heliostats to reflect the sun’s energy to a boiler atop a tower to produce high temperature and high pressure steam. The steam is used to turn a conventional steam turbine to produce electricity.

9

In BrightSource’s SolarPLUSTM plants, the steam is directed to a heat exchanger, where molten salts are further heated to a higher temperature, thus efficiently storing the heat energy for future use. Later, when the energy in storage is needed, the heat stored in the molten salts is used to generate steam to run the steam turbine. What is the storage medium being used? BrightSource is implementing a proven two-tank molten salt system. The molten salt mix is composed of 60% by weight sodium nitrate (NaNO3) and 40% potassium nitrate (KNO3). This mixture is also known as “solar salts” because of its widespread use in the solar thermal industry. What are the benefits of integrating thermal energy storage? There are five main benefits associated with integrating thermal energy storage: - Reducing the total energy costs by increasing a plant’s capacity factor – the amount of hours that a plant

runs annually - Shifting electricity production to periods of highest demand - Providing firm capacity to the power system; replacing the need for conventional power plants as opposed

to just supplementing their output - Providing ancillary services such as spinning reserves to help support a reliable grid - Avoiding the variability and integration costs that other renewable resources like photovoltaics (PV) and

wind create for utilities and grid operators; reducing the need for additional fossil fuel units required to back up intermittent renewables that put a hidden financial burden on ratepayers

Where can I find technical information about the value of thermal energy storage and CSP? Utilities value solar thermal plants as a reliable power source, much like a conventional power plant. Large solar thermal plants will continue to be highly attractive to utility customers because they can produce significant amounts of reliable, dispatchable electricity. Solar thermal with storage avoids the intermittency issues associated with photovoltaic solar and wind generation, which is a necessary power characteristic to maintain a stable grid for utilities and their customers. Solar thermal integrates more seamlessly into the transmission grid because it has similar flexibility as a conventional thermal plant. As thermal energy storage is added to solar thermal power plants, solar thermal becomes even more valuable because stored energy can be used to accommodate the variability of other non-dispatchable renewable, including wind and PV. Stored energy can also be used to meet electricity demand in the late afternoon and early evening hours, after the sun has gone down and PV output drops. This extra generation is highly valued by utilities. Recent studies have shown CSP with thermal energy storage is much more competitive when the comprehensive net grid system costs of the CSP plant are compared to wind or solar photovoltaics (PV). These net costs include the long-term energy, ancillary service and capacity benefits and have been shown to provide an additional $30-60/MWh, or even higher, of benefits when compared to a PV plant with equal annual energy production in high renewable penetration scenarios. For more information on the value of solar thermal with thermal energy story, download our new report The Economic and Reliability Benefits of CSP with Thermal Energy Storage here.

10

How does a SolarPLUSTM plant reduce energy costs? SolarPLUSTM plants reduce energy costs by increasing its capacity factor – how much power a plant produces – and through improved efficiencies of BrightSource’s solar thermal technology compared to competing commercial solar thermal technologies. These efficiency advantages are found in plants with standard solar and those with storage, and reduce costs by requiring less capital investment. What are the advantages of BrightSource’s storage approach vs other solar thermal technologies with storage? When compared to other commercialized solar thermal plants with storage, our primary advantage is in our solar thermal technology’s ability to reach higher temperature and pressure levels, which allows our plants to run more efficiently with or without storage capacity. These higher efficiency levels result in improved economics in solar and storage power production. ENHANCED OIL RECOVERY What is enhanced oil recovery? Thermal enhanced oil recovery (EOR) is used in “secondary” and/or “tertiary” phase oil fields where oil remaining in an underground reservoir is both too low-pressure, and too viscous, to freely flow to the surface. “Steam flood” thermal EOR manipulates oil production by “flooding” the reservoir, via a separate injection well, with very hot, high quality steam in order to increase reservoir pressure and reduce the viscosity of the resource. Thermal EOR requires a number of conditions: a high reservoir porosity, a field depth of 500-5000 meters, and most importantly, an oil ‘gravity’ less than 20. Steam itself must also be matched to a specific reservoir with an optimal pressure, temperature, and quality. What are the benefits of using solar thermal technology for enhanced oil recovery? Thermal EOR helps avoid CO2 and other airborne particulates, creates new jobs, and frees up natural gas for other uses, providing a hedge against volatile natural gas prices. In many places in the world today, solar thermal EOR can be a cost-effective solution compared to alternatives such as liquefied natural gas. COST & VALUE How much electricity does from BrightSource’s plants cost? For competitive reasons, we do not disclose the exact cost of electricity produced at our projects. However, given our capacity factor and efficiency advantages, we believe that our projects are lower than other leading solar technologies and will continue to drop in cost through deployment of our technology. The CSP industry has a history of significant cost reductions when introducing new technologies. The SEGS plants reduced costs by 50% over nine plants. With next generation technologies being deployed today, we believe that similar cost reductions can be achieved with power tower technology as well. How do you plan to reduce the cost of your plants? Cost reductions with BrightSource’s technology come from continued cost reductions in the solar field, power plant, receiver/heat transfer and thermal storage components.

11

ENVIRONMENTAL BENEFITS What are the environmental advantages of BrightSource’s technology?

Our pylon-based heliostats avoids sensitive plant habitat and allow for building around the land’s natural contours, which requires less grading and the use of extensive concrete pads than other solar thermal technologies. For example, with our technology, we can place pylons directly in the ground, without concrete pads, which allows for vegetation to exist within the field below the mirrors. We can also build on up to a 5% grade, meaning that we do not have to grade the site to achieve perfectly flat land, unlike PV and parabolic trough technologies.

We can use dry-cooling, despite its additional cost, to reduce water usage by more than 90% over competing technologies.

Unlike trough technology, the power tower design does not require the use of oil or other synthetic chemicals to produce electricity.

Our plants are more land efficient than competing solar technologies. How does BrightSource select the sites for its projects? When determining where to site our projects, we use a very stringent set of environmental and generation criterion including:

Sites with existing nearby transmission

Areas with high direct natural solar insolation, which decreases the amount of land required

Sites close to development or that have already had pre-existing human impact

Areas that do not contain any Desert Wildlife Management Area (DWMA), area of critical environmental concern (ACEC), Wildlife Habitat Management Areas (WHMAs), nor any other designated critical habitat

Do you work with environmental groups to develop your power plants? We work closely with a number of local and national environmental groups when planning and executing our solar thermal plants. Feedback from these groups is essential in designing and deploying a thoughtful utility-scale solar plant. How does BrightSource’s technology reduce water use? We are setting the bar for very low water use. Our projects can feature a dry-cooling technology, which allows the project to reduce water usage by more than 95% compared traditional wet-cooling methods. For example, the water consumed on the Ivanpah project – roughly the equivalent of 300 homes’ annually – is for cleaning the mirrors, much like a PV plant of similar size. Do you protect species found on your project sites? We go to great lengths to protect and care for the plant and animal species found on our solar power project sites. For example, at our Ivanpah project, we have a comprehensive desert tortoise protection program onsite, including a “Head Start” tortoise hatchery program. For more information on the “Head Start” program, please visit the following blog post. We approach native plant life with the same level of care. In addition to allowing for trimmed vegetation to co-exist in the field of mirrors, we can also avoid areas of sensitive plant life. For example, at Ivanpah, we have a native plant nursery and have identified areas within the solar field, which call “halos,” where we do place heliostats.

12

SPECIES PROTECTION Is the desert tortoise an endangered species? The desert tortoise is federally-listed as a threatened species – not an endangered species. “Endangered” is a more serious designation within the Endangered Species Act, meaning that the species is currently on the brink of extinction. “Threatened” species do not currently face the same risk, although they are protected to help prevent their becoming endangered. What steps are you taking to protect and repopulate the desert tortoise populations at Ivanpah?

Financial Investment: The Ivanpah project owners have to date spent approximately $22 million caring for the desert tortoises found on or near the site. In addition, we will spend up to $34 million to meet the project’s federal and state mitigation obligations.

Biologists: At any given time, there are dozens of trained, Agency approved (Bureau of Land Management, US Fish & Wildlife Service, California Department of Fish & Game and California Energy Commission) biologists on site to make sure that every tortoise on site is given the highest levels of care. At certain periods of construction, there have been over 150 biologists on the project.

Nurseries: The tortoises found on the project site were first moved to a designated nursery where biologists carefully recreated their burrows and provided food and water. While in the nursery, biologists ensured that there was no interaction between the tortoises and conducted the appropriate medical tests to ensure the animals were healthy and free of a respiratory disease common in the species.

Juvenile “Head-Start” Care Program: All juvenile tortoises, classified as tortoise under 120mm in size including newborn hatchlings, will be provided specialized “head-start” care and protection for approximately the first five years of life, or until they are large enough to resist predation from ravens, kit foxes, and coyotes and other factors such as drought and disease.

Translocation: Eventually, all of the tortoises cared for on the project site will ultimately be relocated back into their natural habitat nearby. The majority of the tortoise will remain within their original “home range” (unlike tortoises translocated long distances to unfamiliar habitat) and will have comparable plant diversity and richness as the Ivanpah site. Keeping the tortoise close to their original homes greatly increases the rate of success for translocation.

Long Term Monitoring: Biologists will track the tortoises that are translocated from the project site as well as the tortoises outside the project site within the “receiving” area for five years. A total of 80 adult and sub adult tortoises were found on site, as well as 93 juvenile tortoises many thought too small to be detected. An additional 53 tortoise were hatched in the tortoise nurseries in the fall of 2011. The biologists will use tracking information from nearly 400 tortoises, including those in nearby populations that are monitored as “controls” for tortoise found on-site, or in areas that will receive tortoises that are moved off-site, to ensure the safe integration and gather additional insights on the desert tortoise and its recovery.

What is the natural survival rate of the desert tortoise? In its natural environment, only about 2% of desert tortoises survive to adulthood (reproductive age). Tortoise care programs for hatchling (newborn) and juvenile tortoise provide a critical path for improving survival rates by providing support and protection from ravens, kit foxes, and coyotes and other factors such as drought and disease during approximately the first five years of life.

13

What can be done to help increase the survival rate of desert tortoise? In an effort to help facilitate the rebuilding of the desert tortoise population in the Ivanpah Valley area, we have developed a world-class juvenile “head-start” care program at the Ivanpah project. Head-start care programs provide support and protection for hatchling and juvenile tortoise during approximately the first five years of life, or until they are large enough to resist predation and other factors such as drought and disease. At the Ivanpah head start facility, we are currently caring for more than 100 juvenile desert tortoises, including 53 newborn hatchlings born in the fall of 2011. The facility includes highly secure, specialized juvenile tortoise pens that carefully protect from predators – which include ravens, raptors, ground squirrels and coyotes. Head start programs have been found to provide a critical avenue for enhancing repopulation of the desert tortoise. How much land within the Mojave Desert is designated for desert tortoise habitat? Desert tortoise habitat is divided into six large areas, called “recovery units,” spanning tens of millions of acres across Arizona, California, Nevada and Utah. The Ivanpah site is within the approximately nine million-acre Northeastern Mojave recovery unit, comprising approximately four hundredths of one percent (0.04%) of the unit’s total acreage. In the Ivanpah Valley alone, over 630,000 acres have been designated as Critical Habitat for desert tortoise. The Ivanpah site is not located within any defined Critical Habitat, and has been designated by the BLM as “Category 3” habitat – the “least important” category of habitat for the desert tortoise. In total, over 6.4 million acres have been identified as critical habitat for the tortoise across the six recovery units, including 4.75 million acres in California. How will your desert tortoise care and protection efforts affect the tortoise population long-term? As a result of our tortoise care and protection efforts, many more healthy tortoises will be returned to the Ivanpah Valley than would have survived had the Ivanpah project not been built. Additionally, each of the translocated tortoises, their hatchlings living in the head-start program and the recipient tortoise population are being studied extensively by biologists. The data gleaned at the Ivanpah project will help the desert tortoise biologist community learn more about the species and determine additional ways to help the population once again flourish. Which public agencies do you consult with on your tortoise care efforts? We work extensively with government agencies such as the California Energy Commission, Bureau of Land Management, California Department of Fish and Game, U.S. Fish and Wildlife Service, Mojave National Preserve and the environmental community to develop a thoughtful and responsible tortoise care and mitigation strategy. The project also underwent stringent California Environmental Quality Act and National Environmental Policy Act reviews. What is solar flux? Solar flux, or concentrated sunlight, is a measure of how much light energy is being radiated in a given area. Solar flux can be characterized by the familiar W/m² or kW/m². There is more than one type of flux, and while related, heat flux is not the same as solar flux. Thermal energy, or thermal flux, is what we call heat. It is a different form of energy, easier to understand physically – it is mostly from atoms or subatomic particles moving excitedly. Thermal energy is a form of energy that is internal to an object. Thermal energy – heat – can be transferred from one object to another in one of three ways: by

14

conduction, convection and radiation. Conduction is heat transfer directly from one object to another in contact with it (e.g. touching a hot stove), and convection is when thermal energy is conducted to fluids such as liquids or gases that then carry the heat away (e.g. blowing on hot soup). How does solar flux impact birds? The U.S. Fish and Wildlife’s Office of Law Enforcement (OLE) was asked to examine the causes of bird mortality at three solar energy facilities in California, including the Ivanpah project. The OLE biologists found that “significant avian mortality is caused by the intense solar flux that produces feather singeing.”* BrightSource is committed to minimizing avian impacts at the projects utilizing our technology. We support the use of technologically advanced cameras, radars and audio systems to assist in detecting, monitoring and deterring bird movement in and around solar facilities. For more on solar flux, read our blog post. *Source: National Fish and Wildlife Forensics Laboratory, Rebecca A. Kagan, Tabitha C. Viner, Pepper W. Trail, and Edgard O. Espinoza: Avian Mortality at Solar Energy Facilities in Southern California: A Preliminary Analysis Are birds “vaporized” by solar flux? There is no scientific evidence that birds can be “vaporized” after traveling through solar flux. In fact, OLE biologists found evidence to the contrary. “Birds appear to be able to survive flux burns in the short term, as evidenced by the collection of several live birds with singed feathers.” What steps are you taking to protect and mitigate avian deaths at Ivanpah?

The Ivanpah project owners are implementing its Avian and Bat Monitoring and Management Plan approved by state and federal agencies and required by permit. Under the approved plan, Ivanpah reported 321 avian fatalities between January and June 2014, of which 133 were related to flux.

The Ivanpah project owners are studying the use of humane avian deterrent systems similar to those employed by airports and implementing other practices that go beyond conventional operational procedures to reduce bird and bat activity at the facility. These deterrent considerations include:

o Active detection and deterrent methods, such as radar and infrared systems o Anti-perching devices o Screening and sonic deterrent methods o Waste and water containment and insect control to ensure that avian species are not drawn near

the facility in search of food sources o Replacing the current conventional lighting with LED o Heliostat repositioning for flux management, which allows us to generate the renewable energy

required by our partners in southern California while minimizing the level of flux What are the leading anthropogenic causes of bird deaths? The leading anthropogenic causes of bird deaths include:

An estimated 1.4-3.7 billion birds are killed each year by cats;

As many as 980 million birds crash into buildings annually;

174 million birds die from power lines every year;

Up to 340 million birds perish from vehicles/roads;

Approximately 6.8 million birds die flying into communications towers;

As many as one million die annually in oil and gas fluid waste pits; and

15

Up to 330,000 die each year from wind turbines

Source: CEC Docket Number 09-AFC-07C, Palen Solar Power Project – Compliance, TN# 202736: Exhibit 1157. Anthropogenic sources of avian mortality and associated estimates of the number of birds killed per year.

DRY COOLING How does BrightSource’s solar thermal technology conserve water? In BrightSource’s solar technology, we use water in two primary ways: to clean the heliostat mirrors and to produce steam for electricity generation. Water is not consumed during power generation. To produce steam from the sun, we use tens of thousands of computer-controlled mirrors to track the sun in two dimensions and reflect the sunlight to a water-filled boiler that sits atop a tower. When the concentrated sunlight strikes the boiler’s tubes, it heats the water to create superheated steam. This high-temperature steam is then piped from the boiler to a conventional steam turbine-generator where electricity is generated. In order to conserve water, we use a dry cooling process to condense the steam back to liquid water, which is then cycled back to the boiler in a closed loop cycle. The minimal amount of water consumed by a BrightSource power plant is used from the cleaning of heliostat mirrors, and even this water is made up of partially recycled boiler water. How much water is used in a BrightSource Energy solar thermal plant? The amount of water used varies depending on the size of the plant. For example, our 392 (gross) megawatt Ivanpah solar plant will use approximately 100 acre feet of water each year. This is comparable to the amount of water used by 300 households annually, and less than the amount used to water two holes of the nearby 36-hole golf course. What is dry cooling? In thermal steam systems, the super-heated steam inside the boiler pipes must be cooled and condensed back into water in a closed loop system. Dry cooling, or air cooling, uses an air-cooled condenser comprised of many large fans to circulate air over the pipes to cool and condense the steam. By comparison, a wet cooling system will circulate water across the pipes to cool and condense the steam. What are the benefits of dry cooling? There are a number of benefits to using a dry cool system. The primary motivation to use dry cooling for BrightSource is to conserve scarce water resources in the arid desert climates where we build our plants. Overly taxing an area’s water resources can very seriously damage the biological ecosystem of the area, negatively impacting both animal and plant species. Dry cooling requires 90 percent less water than competing wet-cooled or hybrid dry-wet cooled systems. By using dry cooling, we are also able to eliminate the need for evaporation ponds and extensive water treatment facilities, which provide us with greater flexibility on where we can site our solar power plants. Beyond water, what are the impacts of dry cooling compared to wet cooling? The primary impact of using a dry cooling system are the slightly increased cost and the loss of efficiency. Power tower is the most cost-effective dry cooling plant because it produces more power, offsetting the additional cost

16

per unit of electricity and has the ability to produce higher temperature steam, which results in a smaller efficiency loss when interfacing with dry cooling technologies. Dry cooling requires large fans to cool the water, which adds no more than a couple percentage points to a plant’s capital costs and efficiency loss that varies depending on the ambient air temperature. By nature, dry cooling requires large fans to cool and condense the steam, and these fans require electricity to operate. The electricity required to operate the fans takes away from the total amount of electricity that can be sold to a customer, referred to as “parasitic loss.” The warmer the ambient temperature, the larger the parasitic loss. How does BrightSource’s technology overcome the challenges of dry cooling? BrightSource’s technology is designed to produce high temperature and pressure solar steam. At Ivanpah, water is heated to 538 degrees Celsius, or 1000 degrees Fahrenheit. Competing parabolic trough systems or molten salt tower systems are limited by temperatures that the heat-transfer medium such as molten salt or synthetic oils can reach. This technological advantage lets us use more of the steam’s heat energy (enthalpy) to more efficiently power a steam turbine-generator. As a result, our solar thermal power systems can produce more electricity than competing technologies. Our ability to produce and sell more electricity makes dry cooling an economically viable choice. It significantly reduces the cost implications of using a more expensive dry cooling system, and it also reduces the percentage of overall parasitic load. How does an air-cooled condenser work? An air-cooled condenser (ACC) condenses the steam by forcing ambient air over tubes that contain the steam that exits the turbine. ACCs are typically comprised of modules arranged in parallel rows, with each module containing a number of finned tube bundles. An axial flow, forced-draft fan located under each module forces the cooling air across the heat exchange area of the finned tubes. What does an air-cooled condenser physically look like? What are the main components?

17

The ACCs at Ivanpah (above, structure to the left of the tower) provide a good example of the main components of an ACC and what the equipment looks like. The three ACCs at Ivanpah each have 15 modules, placed in a 3 x 5 arrangement, with overall plot area of ~ 242 ft. L x 125 ft. W x 97 ft. H. Each module has a 36 ft. diameter fan, driven by a 200 HP motor. The ACC is raised off of the ground to reduce the amount of dust and debris that enters the system. NATURAL GAS How is natural gas used in the operation of Ivanpah? A small amount of natural gas is used at Ivanpah to achieve quicker morning startup and longer solar generation at the end of each day, as well as for the safe and reliable operation of the solar receiver and steam turbine. Each of the Ivanpah units has an auxiliary boiler and night preservation boiler. The night preservation boilers are very small boilers used overnight to maintain seals and preserve heat. The auxiliary boilers are used for:

Morning startup

Daily shutdown

Supplementing solar generation during periods of transient clouds or at the end of the day

Standby to avoid turbine trips during passing clouds, and

If a trip occurs, to ensure the quickest restart, if feasible based on weather conditions. This type of use of natural gas does not produce electricity. In fact, it increases the amount of electricity produced from the sun through:

Preparing the facility each day to utilize the solar resource as soon as practically possible, and safely.

Prudent maintenance of the facilities that reduces unplanned outages, and therefore, ensures the maximum amount of solar generation from the facility.

How much natural gas can Ivanpah use each year? Ivanpah has an annual maximum fuel usage, per unit, of 525 mmSCF. This increases Ivanpah’s maximum annual metric tons of CO2 emissions from ~18,000 to ~28,600. This is approximately 185 lbs. of CO2 per megawatt hour (MWh), compared to the proposed EPA limitation of 1,000 lbs./MWh for a new combined cycle gas turbine (CCGT). Coal plants produce more than 2,000 lbs./MWh. The California Legislature recognized the benefit of using a small amount of natural gas to maximize renewable energy production in its analysis of AB 1954 (Skinner), signed into law by Governor Brown in 2010:

This bill directs the Energy Commission to set the "de minimus" amount of non-renewable energy that may be included with renewable energy at no more than two percent of total fuel use. The bill also authorizes the Energy Commission to allow up to five percent to come from non-renewable fuels, on a case-by-case basis, if the Energy Commission finds that the additional use of non-renewable fuels will lead to an increase in overall renewable energy generation and reduce variability in generation. It also specifies that in order to qualify for more than two percent non-renewable fuel use, the non-renewable fuel must come from either natural gas or hydrogen derived by reformation of a fossil fuel.

Ivanpah filed for amendment to increase natural gas usage for this purpose and the amendment was granted by the Energy Commission. The project’s use of natural gas remains within the de minimus requirement as defined by the renewable portfolio standard (RPS) to be considered RPS-eligible delivered electricity.