The Trade-Off Between Water and Energy: CSP Cooling Systems Dry Out in California

This is the third in a series of blog posts discussing the water-energy nexus.

Luz Solar Energy Generating System (SEGS) III at Kramer Junction, Califoria

Solar Parabolic Trough in Califoria – Courtesy of Sandia National Laboratory

Large-scale solar power is coming to the United States. After much debate about water conservation and land preservation, the California Energy Commission (CEC) recently approved plans for nine concentrating solar power (CSP) plants in the state. Worldwatch found that this group of proposed plants will consume much less water per megawatt-hour than if California was to build typical coal, natural gas, or nuclear power plants instead. These CSP plants minimize water use through dry cooling.

The CEC expedited its commissioning process this fall to approve the CSP projects before their eligibility for a 30-percent cash grant from the U.S. Treasury’s 1603 Program expired at year’s end. Luckily for U.S. solar developers, Congress has since extended the program through 2011, as I discussed in a previous post. The approved projects represent a total of 4.4 gigawatts (GW) of new installed solar power capacity (or 4.6 GW if a tenth project, which should be approved shortly, is included).

The new CSP projects would increase California’s grid-connected solar power capacity fourfold from the 2009 level. Considering that California has the largest solar capacity in the country—about 10 times larger than any other U.S. state—this is all the more impressive. The development will dramatically assist California in meeting its renewable portfolio standard (RPS) target of generating 20 percent of its electricity from renewable sources by 2010, and 33 percent by 2020. More broadly, these projects would increase the nationwide supply of non-hydroelectric renewable power by over 9 percent, based on 2009 figures from the U.S. Energy Information Administration.

Water consumption has been a central issue in the commissioning process. Mindful of water usage, the CEC has recommended the use of dry cooling systems for the new CSP projects, which in some cases could reduce water consumption by up to 90 percent with minor efficiency losses and added costs (as I discussed in a previous post). Of the ten CSP projects in the pipeline, eight rely on dry cooling.

Compared to conventional sources of electricity, CSP with dry cooling is more water efficient. Our calculations suggest that the average lifecycle water efficiency of the 10 new plants would be 120 gallons per megawatt-hour (gal/MWh), even including the two water-intensive plants that use wet cooling towers. [Water consumption during construction, which accounts for a small portion of lifetime use, was not included in this estimate.]

For contrast, estimates from a recent Worldwatch briefing paper indicate that a typical Powder River Basin coal power plant with wet cooling uses 523–1,084 gal/MWh, and a typical natural gas combined-cycle power plant with conventional gas and wet cooling uses 124–525 gal/MWh. Meanwhile, a Congressional Research Service study indicates that a typical nuclear power plant with wet cooling uses 475–900 gal/MWh.

Clearly, CSP plants with dry cooling systems offer California commercial-scale power with minimal water usage, but not all of the new projects are created equal (see Full CSP Spreadsheet). Below, I discuss the differences in cooling and generation technology for the 10 proposed projects:

Concentrating Solar Power Plant Development in California during 2010

Source: Worldwatch, CEC, NREL

When the CEC approved NextEra’s 250 MW Beacon Solar Energy Project at the end of August, it was the first all-concentrating solar plant to be commissioned in California in 20 years. Like most of the other proposed projects, the Beacon plant will use parabolic trough technology. Here, sunlight is concentrated into a focal point at the center of the collectors, and vacuum tubes that run the length of the trough transfer a heating fluid (usually oil or water heated to 750 degrees Fahrenheit) Fahrenheit to the boiler to make the steam needed to generate electricity.

Yet Beacon is one of the two proposed CSP plants that will not use a dry cooling system. Instead, it will have a wet cooling tower, where the low-pressure steam exhaust from the Rankine cycle generator-turbine is cooled by evaporation after passing through a heat exchanger. Potentially, half or more of the water in the cooling tower is lost to evaporation, creating the need for additional (makeup) water, but any remaining water will be condensed and collected for reuse. Over 90 percent of the project’s water needs will be met with recycled water from nearby wastewater treatment facilities in the towns of California City or Rosamond. Nonetheless, the plant will still require 456 million gallons annually to operate and cool, equivalent to the annual water consumption of 5,600 families in the U.S. Southwest.

Abengoa Mojave
The Abengoa Mojave Solar Project was the second commercial-scale CSP plant to be commissioned this fall. Like the Beacon project, it uses a 250 MW parabolic trough system; however, it will be substantially more water efficient, consuming some 277 million gallons per year due to advanced water recycling and reuse techniques. The plant will collect the condensate from the generator’s reject streams after being run through reverse-osmosis filters in a service water-storage tank for recycling. Further water storage will be available in a clear well when discharge exceeds the treatment system demand. Lastly, the treatment system will draw recycled service water first rather than pumping virgin makeup water from the site’s groundwater wells.

Developers at Solar Millennium LLC have been involved in several CSP projects in the U.S. Southwest. The recently approved Blythe Solar Power Project in southeastern Riverside County comprises four adjacent 250 MW parabolic trough systems with a combined capacity of 1 GW—roughly the capacity of an average nuclear power plant. The project is so large that it will nearly double the current U.S. installed CSP capacity. Additionally, Blythe is the first CSP plant in California to propose using dry cooling—specifically, a closed-loop apparatus known as an air-cooled condenser (ACC). Despite its size, Blythe will consume less water than either Beacon or Abengoa Mojave. Every year, Blythe will use 196 million gallons of water from 10 groundwater wells for feedwater makeup, mirror washing, and on-site domestic use. Each of the four power plants will also have an auxiliary closed-loop wet cooling system for ancillary equipment.

Unlike most of the other CSP projects, the 370 MW Ivanpah Solar Electric Generating Station will use a central power tower rather than a parabolic trough system. Sunlight is reflected from the mirrors to a single receiver atop the tower in order to heat a transfer fluid that is used to create steam to run the generator-turbine below. The Ivanpah project will use dry cooling via an ACC, enabling the plant to consume only some 33 million gallons of water per year. It is worth mentioning that Ivanpah was the first project to file for CEC approval (back in 2007), but it hit resistance from environmental activists who were concerned that the project would displace a large population of desert tortoises from their native habitat in the Mojave Desert.

Imperial Valley
The Imperial Valley Solar Energy Project will use a third type of CSP technology. The 750 MW project, formerly known as the Stirling Energy Systems (SES) Solar Two Project, will rely on 30,000 mirrored parabolic dishes that power the solar Stirling engines to produce electricity. Each dish concentrates sunlight on a receiver that is housed in a power conversion unit (PCU) that sits on a boom above the dish and heats the working fluid—in this case, hydrogen rather than steam—to run the Stirling generator-turbine, also located in the PCU. The project uses SES’s unique dish-engine units, called SunCatchers™, which operate independently and generate electricity without water. The only water consumed at the plant will be primarily for mirror washing and demineralization processes in the treatment system. The Stirling engine’s small closed-loop dry cooling system also may require minimal water to compensate for leakage. The hydrogen will be separated from water through electrolysis, requiring only negligible water input. Total annual water consumption at the plant is estimated at 11 million gallons, roughly the usage of 131 Southwestern families. However, Imperial Valley has the largest land footprint of the new CSP projects, occupying 6,500 acres.

The Genesis Solar Energy Project originally proposed using a wet cooling system, but the CEC reviewers deemed that dry cooling would be feasible for the project and called for the developers to replace the wet cooling tower with an ACC. This decision will reduce the plant’s annual water usage more than 87 percent, from 521 million gallons to only 65 million gallons. But the switch will also increase construction costs and decrease the plant’s electricity output, especially during the summer when hotter ambient temperatures strain the dry cooling system’s efficiency.

Originally part of a larger group of projects that included the Imperial Valley plant, the Calico Solar Power Project (formerly the SES Solar One Project) was taken over by different developers and has a new operating capacity of 850 MW. Like Imperial Valley, Calico will use Stirling engine and dish technology, but it will have 34,000 units. Because Stirling engines are more efficient than the Rankine engines used at other proposed solar thermal plants in California, a Stirling plant can generate more electricity per year with the same capacity and acreage. Calico also has the lowest estimated water consumption of any of the approved projects, at 6.8 million gallons per year, which is even lower than Imperial Valley despite being larger in size. One major drawback of Calico is that it requires 4,600 acres of land, which will have negative effects on the local environment including the clearing of vegetation and the dislocation of wildlife.

CSP Plant in the Mojave Desert - Wikimedia Commons / Alan Radecki

CSP Plant in the Mojave Desert – Wikimedia Commons / Alan Radecki

A few weeks ago, it was doubtful that the Palen Solar Power Plant would even be able to start construction or pay the 5 percent of its equipment costs required to receive the U.S. Treasury 1603 cash grant before the December 31 deadline. But when Congress extended the 1603 program, the CEC went ahead and approved the project. As a sister project to Blythe, the Palen plant is also being developed by Solar Millennium in Riverside County, but it will have only half the capacity, at some 500 MW. Like Blythe, Palen will use an ACC for dry cooling but will consume no more than 96 million gallons of water per year for operation and cooling.

The Rice Solar Energy Project also might have died without support from the 1603 program, but both Rice and the Palen project were approved on December 15, only days after the 1603 extension. Rice will be the second new CSP plant to have a central power tower (like the Ivanpah plant), but it will use molten liquid salts as a heat-transfer fluid rather than synthetic oil or super-heated water. Because the salts retain heat extremely well, this gives the plant thermal storage ability, making it the only one of the 10 new plants to be able to generate electricity at night. Rice also has the smallest capacity of these plants, at only 150 MW. It will rely on a dry cooling system, consuming an estimated 49 million gallons of water annually.

The Ridgecrest Solar Power Project is the only project currently in the CEC’s pipeline that has yet to be approved. Developed by Millennium Solar, it proposes using a parabolic trough system and has an installed capacity of 250 MW—about a quarter the size of Blythe and half the size of Palen. Ridgecrest will be located in northwestern Kern County and will use an ACC for dry cooling, consuming roughly the same amount of water as the Rice project, at 48 million gallons per year. Considering how quickly the other Solar Millennium projects have moved through the commissioning process, the Ridgecrest project will likely be approved by the CEC in the next month or so.

Figure 1 provides a comparison of the 10 CSP projects. For reference, my full spreadsheet of data and calculations is available here.

The massive proposed development of CSP in California will have vast implications for the U.S. renewable energy industry. The CEC has done its best to ensure that water resources in the arid Southwest will not be exacerbated by this CSP boom. California has not just laid out a model for renewable energy growth—it has created a paradigm for sustainable energy development that minimizes water consumption.

Go to Source

Renewable Energy Not a “Competing” Priority in Haiti

Recently the Brookings Institution hosted a panel that examined Haiti’s political and humanitarian developments since the January 2010 earthquake. A theme that came up regularly was that of competing priorities such as turbulent elections, a cholera outbreak, a lack of dependable energy supply, and gender-based violence.

As the Worldwatch Institute prepares to develop a Low-Carbon Energy Roadmap for Haiti, some have questioned whether limited donor resources should be channeled into something more pressing than assessing and improving the country’s energy infrastructure. Is an energy roadmap really needed right now, or are other matters more important?

Departments of Haiti

Haiti: Many sections, many challenges.

The cholera outbreak in Haiti is an urgent matter that deserves all the attention it is currently receiving. However, we must keep in mind that a lack of proper sanitation – due to a lack of electricity – helped cause the recent outbreak. Had the country’s energy infrastructure been more robust and sustainable, basic sanitation and electricity in hospitals might not have been lost and the current epidemic might have been avoided.

To be clear, Worldwatch is not suggesting that the Low-Carbon Energy Roadmap project we are undertaking is more important than addressing the cholera outbreak. But we believe that keeping an eye focused on the long term – while simultaneously addressing immediate concerns – can start a process that will help prevent such outbreaks in the future.

The bottom line is that without an effective energy infrastructure, basic services essential to public health will fail. The earthquake’s devastation worsened an already-dilapidated infrastructure leaving Haiti with no choice but to use diesel generators for its electricity. Given the recent run up in oil prices and the over-stretched Haitian budget, the diesel solution is tenuous at best. And though this seems like the only choice Haiti has, it’s not. Considering the high amounts of attention and financial aid Haiti is receiving these days, decision makers can exercise the choice to put into place something more sustainable.

This is where Worldwatch comes in. As we wrote previously, Haiti’s recent crisis is also a great opportunity for the country to reinvent itself with more sustainable solutions and to invest in projects that serve the long-term. While addressing the cholera outbreak is of utmost importance, the international community must simultaneously recognize that now is the time for Haiti to start putting into place a more sustainable energy system.

René Jean-Jumeau, the coordinator of the Energy Unit within Haiti’s Department of Public Works states that Haiti needs a plan to, “[finance] the development of a new framework to be able to essentially modernize the Haitian energy sector to put the sector into a more sustainable state.”

The Low-Carbon Energy Roadmap Worldwatch is designing for Haiti will do just that. It is a sustainable framework that will help reduce oil imports and save the country significant amounts of money in the long run. That money can be invested in other areas of development to ensure basic services like sanitation and hospitals never falter again.

Incredible amounts of capital are being spent on the pressing epidemic of Haiti but as we highlighted previously, a significant share of global aid money goes toward projects lasting eight years or more. So while the cholera outbreak is being taken seriously, it is equally important to channel some of the donations now flowing into Haiti towards building an energy portfolio that capitalizes on the island’s indigenous energy sources beginning with solar and wind.

Funds invested in energy infrastructure now will mean lower government expenditure on oil later – and more money to be invested in the country’s development. Otherwise Haiti risks being locked into dependence it can’t afford and will be caught unprepared for future crises – both natural and man-made. Worldwatch’s project is not in competition with the effort to stamp out cholera – it is a piece of the larger puzzle working with efforts like this to move Haiti forward.

Go to Source

Ten Highlights and Ten Thousand Thanks from Twenty Ten

Here it is: The final post of 2010. The year went by so very quickly, but before it’s over, I want to give thanks for all the help I received spreading the message of State of the World 2010—the message that to create a secure future, those of us who understand the finite nature of Earth will need to get into the business of cultural engineering, making it as natural to live sustainably as living as a consumer feels today.

So, THANK YOU. Thank you to all those who made the book possible: the authors, my colleagues, our publishing partners, and everyone we thanked in the Acknowledgments. But THANK YOU also to all the individuals and institutions that played an instrumental role this past year in getting the word out around the world, helping to create 12 additional translations of State of the World 2010 (with two more still to come). Thanks also to the media who shared the report, the many groups that invited me to present, and the sustainable consumption practitioners who invited me into their conversations and gave me additional fora to discuss the findings of the book. And of course, THANK YOU to all those who read the report, this blog, and my Facebook updates, and who shared the ideas they contain with friends, colleagues, fellow students, and wider social networks and communities.

When I sat down to write this, I thought I’d create a blog-style acknowledgments to thank people personally. However, the list became very long, and I know that no one will read a list of 500-plus names. So instead, I want to share 10 highlights from 2010 that really made the year special and that hint at just how much work by so many people went into making this effort a success.

1) Of course, we have to start with the January 2010 press launch, which spurred the first round of coverage of the report—with the great help of the Worldwatch media team—and paved the way for broader coverage throughout the year. Rush Limbaugh’s discussion of the report was definitely a funny way to start the year.

2) Then came the State of the World Symposium in Washington, D.C., where along with a fantastic series of speakers, we served roasted grasshoppers to our audience of supporters in order to challenge their cultural assumptions (in this case, about what is and isn’t food) and to open them up to the idea of proactively and intentionally reshaping cultural norms.

3) Starting in February, I commenced my own fossil fuel binge, traveling to and around Europe to share the findings of the report. The total emissions tally at the end of year for the travel (for all authors) was about 15 tons, which I hope will be offset by the new wave of cultural pioneers that jump into the fray. The good news is that I kept the total about 5 tons lower by combining trips and doing some couch surfing instead of returning home. The first highlight of this travel was the United Kingdom, where I received wonderful support and hospitality from Earthscan, our British publisher, and did a series of fantastic events across the U.K. (thanks to the help of many). The day-long Transforming Cultures workshop at Findhorn Ecovillage was especially exciting, giving me the chance to see a leading ecovillage in action and to discover that when given the chance, I can talk for an entire day on this topic!

En route to Scandinavia, I stopped in Serbia and met many young pioneers (pictured above) working to embed sustainability into their organizations and cultures. Definitely an inspiring weekend.

4) From the U.K., I headed to Scandinavia—first to Finland, where with the help of Gaudeamus, our publishing partner, we launched the report and had the chance to debate with several ministers and elected officials—as well as to visit a fascinating recycled clothing producer. From there I went to Norway, where I shared the report in Oslo and a few other cities, as well as with the staff of the prime minister, all thanks to Worldwatch’s former board chairman Øystein Dahle. I owe a special thanks to him for all his work to get the message of the report across in Norway—and to live it.

5) After Norway, the pace picked up with a series of jaunts around Europe. In Germany, perhaps the highlight was presenting to a packed house at the Heinrich Boell Foundation, where I ended up debating with the head of the foundation about whether technology or cultural change would save us. You won’t be surprised by which side I took. But you might be surprised at how often I had to work over the course of 2010 to dispel the myth that technology will save us. Too many in the sustainability community have become technological cornucopians, believing that renewable energy, carbon sequestration, nuclear power, or some other magic fix will allow us to maintain our consumer society without destroying the planet. Curing them of this delusion should be a priority of the community.

6) Then on to Spain and Catalonia. Here again, I had great opportunities to share the report’s findings with influential people and groups. I also got an indirect opportunity to influence the United States, the world’s biggest consumer culture, since the U.S. Embassy helped support the trip and played chaperone. I have to admit that this was a bit surreal, especially going to the embassy for a video interview.

Two inspirational highlights of the trip came when I saw a library that was based inside a metro station—ingenious!—in Madrid, and when I attended the Degrowth Conference in Barcelona, where I briefly met a modern-day Robin Hood, a true cultural pioneer who is taking great risks to his liberty and security that few of us are bold enough to take.

7) After wrapping up the European launches, I turned my attention to North America, giving a series of presentations in Vancouver, California, Pennsylvania, Virginia, New York City, and Washington, D.C. But the highlight had to be joining a series of sustainable consumption meetings, where I helped brainstorm new pathways forward. The meetings came in many shades of green, but the most interesting was attended by corporate sustainability officers. Here, I pitched the idea of designing products that lead to less consumption overall and encouraged companies to use their advertising power to shift cultural norms (which advertising does quite effectively). I did have some success. But convincing General Mills to launch a new product, “Veggie Helper,” failed miserably.

What fun it was to present in a castle!

8: Continuing the North American circuit, I found myself in Mexico, thanks to our partner there, Africam Safari. I presented in the two most beautiful locations of the year: the rooftop of Chapultapec Castle (now a museum) in Mexico City and the Africam Safari park in Puebla. More importantly, many influential people were again present, including the Mexican Environmental Minister, who joined the press launch. And best of all, the bug theme continued, with grasshoppers and ant larvae being served to guests in Puebla (but these are specialties there, not taboo foods).

9) In October, I returned to Italy where I joined an international group of journalists at Greenaccord’s annual conference to present the Transforming Cultures message. While there, I continued my Italian outreach, presenting in Feltrinelli bookstores in Genoa and Torin with the help of our Italian publisher, Edizioni Ambiente.

10) The last leg of this odyssey brought me to Greece, where I presented the findings of the report at the launch of Organization Earth—definitely a highlight, as I predict the organization will do great things, as it was created by some incredibly dedicated individuals. The group has exciting plans and is building an Ecomuseum (“The Center of the Earth”—what a perfect name) in a beautiful park in Athens, which hopefully will inspire many new cultural pioneers over the coming decades. Also, I have to admit, seeing an entire set of shelves in the organization’s Eco-bookstore devoted only to State of the World 2010 was quite exciting.

"Hmm, which book should I choose…"

Finally, after much outreach, the year draws to a close. Thank you again to the many who have helped make the year such a success, and I hope to continue spread the Transforming Cultures message out there in 2011 and for many years to come, and hope you will do the same. Happy New Year!

Go to Source