Arizona
Tuesday, November 13th, 2007 at
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source: http://atmoz.org/blog/2007/11/19/tom-hansen-tep-watt-choices-for-the-future/
Tom Hansen (TEP): Watt Choices for the Future
Categories: Climate Change • Energy • Environment
There was a great talk given here last Thursday by Tom Hansen of Tucson Electric Power.
The Germans think that fossil fuels use as primary sources of energy will increase until the year 2030. Right now, solar and other renewable energy sources consitute only a small percentage of our energy supply. However, by the year 2100 they expect that the majority of primary energy will come from renewables – specifically solor power.
Mr. Hansen talked a little about the Energy Policy Act of 2005. He stated that in the law there are incentives given to power companies to build solar power plants. The Wikipedia article for this law does not mention this though. I’m not going to go digging through the original language to try to decipher lawyerese, but I’ll trust Mr. Hansen. He said that the incentives given in the 2005 law are starting to be phased out. That is, the incentives given under the law were very short term (2-3 years). As will be seen, this is not good enough.
Arizona also has a law called the Arizona Renewable Energy Standard and Tariff which calls on utilities to generate at least 15% of their energy by renewables by the year 2025. There is no law that says they must produce 15% renewable energy though. Right now, TEP only produces 0.6% of its energy from renewable resources. They use several methods including solar photovoltaic, solar heat (not sure of the technical term for this is, but it’s the technology they use at their Springerville plant), and methane from landfill gas.
Arizona uses several renewable primary energy sources. However, there are only a few that are viable for long-term growth. Biomass burning, besides producing CO2 and other pollutants, is not sustainable. Only 100-300MW of power can sustainably be obtained from burning wood. Geothermal is a great energy source. It’s both clean and renewable. However, there is little to no geothermal potential in Arizona. Other areas of the world, such as Iceland, have great geothermal sources, and they should be encouraged to use them. Hydro power currently produces about 12% of Arizona power. This is all from dammed rivers. Since there are no plans to build new dams, due mostly to environmental reasons, hydro power is not expected to increase at all in Arizona. Wind power is great. It too is clean and renewable. However, there have been some concerns expressed about their impacts on migratory birds. Wind power has the potential of producing 25,000MW for Arizona. This is a huge amount compared to other sources of renewable energy. However, it is nothing compared to solar.
Here in Arizona we have many sunny days due to the general circulation of the atmosphere. There is a general sinking motion that occurs at 30N and 30S latitude. See here for a brief introduction. The sunny days and relatively low latitude means Arizona is a perfect spot for solar power. It is estimated that solar power plants covering 20% of the land surface of Arizona could support 2,260,00MW at 15-20% “annual capacity factor”.
I’m not sure what exactly “annual capacity factor” means, but he stated that this amount could “feed” the US. I’m not so sure about this as my back of the envelope calculation showed that it would require much more land area than that. Of course, he may have been assuming that solar photovoltaic efficiency would increase before the system was implemented. The major problem with both solar and wind power is their cost and intermitancy. Cost is something that can be handled with subsidies and advances in technology. But we’ll never be able to get the sun to shine for 24 hours at every location on the Earth. (Talk about a global warming!) Therefore, if solar power is going to be a viable energy solution, we need some way to store the power produced during the day to use it at night. Longer-term power storage would also be good, so that excess power produced during one part of the year could be used in subsequent seasons, but that would constitute a huge leap in technology.
Mr. Hansen gave some advantages and disadvantages of the several renewable energy sources. Since I think that wind and solar are the most important for Arizona, only those will be discussed here.
Wind Generation:
- medium capital costs
- uses little water
- reliable ( > 99% )
- low fixed operating costs
- will produce less than 10% of AZ energy without storage
- cost heavily related to capacity factor
– $0.035 – $0.1 / kWh
- average wind must be greater than 16 mph to be a viable source of energy
Solar Generation:
- reliable, but intermittent
- expected to be highly stable
- low to medium fixed operation costs
- very high initial capital costs
- need a storage system, preferably long-tem
- $0.18 – $0.50 / kWh – EXPENSIVE!
At the end of his talk, Mr. Hansen gaves several important facts about solar power.
500 square miles of solar power could produce all of the energy required by the state of Arizona.
The efficiency of the solar cells is related to the temperature. The higher the air temperature, the lower the efficiency.
If all 200,000 single family homes in Tucson has solar photovoltaic cells on their roofs, it would produce approximately 600MW, or roughly 10% of TEPs annual needs.
He finished by saying that “maintaining the energy status quo is not an option“.
I strongly agree.
Arup to design world’s first ‘solar city’ in Arizona
2007 issue 47
By Olivia Boyd
Mixed-use development for 300,000 inhabitants will rely on the sun for all daytime energy
Engineer Arup is planning the world’s first “solar city” in Phoenix, Arizona.
The prospective 33,000-acre development will include housing for 300,000 people as well as high-tech and commercial schemes.
Arup, which is helping to build the world’s first eco-city at Dongtan near Shanghai in China, will play a civil and engineering role. It is thought work on the site is unlikely to begin before 2010.
Gary Lawrence, Arup’s urban strategy leader, said: “We’ve just signed contracts to do a masterplan in Pheonix and that will be the world’s first completely solar city.”
The town will export energy to the grid in the daytime but will have to import it at night as solar panels cannot produce electricity when the sun is down.
It is thought the project will produce energy through a combination of photovoltaic (PV) panels on houses and solar farm technologies, where heat from the sun is used to generate steam and drive a turbine.
Questions have been raised about the suitability of solar technology to the area, where intense heat and dust cut the lifespan of a PV panel to about half its normal length. But it is thought to be the only renewable option in Arizona, where there is little wind or water.
Jonathan Fink, director of Arizona State University’s Global Institute of Sustainability, said the state was trying to catch up with California, which is seen as the American leader in solar power.
He said: “We have a good chance of being the number-two state in the country.”
The news comes after Arizona developers announced plans to build a year-round water park in a desert near Phoenix, where there has been a drought for the past 11 years.
I think that the following article does an excellent job of describing the challenges that the solar industry is faced with, how solar relates with electricity produced to day, and the difference between solar panels and Solar-thermal.
State’s utilities teaming up for major solar project
Plant would help meet green-energy mandate
Ryan Randazzo
The Arizona Republic
Dec. 7, 2007 12:00 AM
Arizona utilities want to build the state’s largest solar-thermal power plant, which could light up thousands of homes and help them meet the state’s renewable-energy requirements.
Arizona Public Service Co., Salt River Project, Tucson Electric Power and several small companies have banded with out-of-state utilities in plans to build the major solar project. They are hoping to save money by concentrating their efforts.
The companies announced Thursday that they are seeking proposals from companies interested in building the project and said that it could be located in either Arizona or Nevada. They want a plant that can generate 250 megawatts of electricity, which is enough juice to power 62,500 to 75,000 homes.
That’s bigger than similar projects in either state and giant by solar standards. But it would produce only about 25 percent of the electricity output of a natural-gas powered plant such as the Redhawk Power Station west of Phoenix.
Sun power is more complex to generate and more expensive than traditional energy. But state regulators agreed last year to the tradeoff in return for non-polluting electricity from one of the state’s most abundant commodities. They imposed a mandate that utilities get 15 percent of their electricity from renewable sources such as solar power by 2025.
The U.S. House of Representative passed a nearly identical nationwide measure Thursday, but the future of the bill is unclear in the Senate.
How it works
Solar-thermal projects use large collections of mirrors to concentrate sunlight on liquids to create vapor and spin turbines to make electricity, much like the steam that spins turbines in traditional power plants. Solar-thermal systems are slightly more cost-efficient than the more common black solar panels that use a semiconductor material to convert the sun’s rays to electricity, utility officials said.
“Our objective is to create a balanced portfolio (of energy),” APS spokesman Steven Gotfried said. “We can get the benefits of the renewable, plus the benefits of traditional power generation.”
SRP is not under the same mandate as other state utilities, but it imposed the same renewable-energy standard on itself.
“We purchase wind power from New Mexico and geothermal from California,” said Lori Singleton, SRP manager of sustainability initiatives and technology.
“Arizona has not identified a large wind or geothermal source here. Looking at our state, solar seems to be the most abundant resource.”
Solar-thermal plants appear to be a better choice than solar panels because, unlike panels, thermal plants can store hot fluids underground to make energy when the sun goes down, officials said.
They also work better where it is hot, whereas excessive heat can reduce the efficiency of solar panels.
Utility officials did not announce how the costs and electricity would be distributed. Proposals from potential builders are due March 19, and the utilities hope to select a builder by June 11. A requirement of the project is to be operational by Dec. 31, 2012.
Arizona utilities will need more renewable projects or contracts to buy renewable energy from neighboring states to meet the renewable-energy standard. Until Thursday’s announcement, most of their renewable-energy focus was on getting customers to install rooftop solar panels at home.
In addition to the Arizona utilities, Southern California Public Power Authority and Xcel Energy Inc. of Minnesota belong to the consortium seeking to build the plant.
APS opened a small, $6 million solar-thermal plant in southern Arizona in 2005, generating 1 megawatt of electricity at the 14-acre facility.
“We were looking at this as a technology that had some viability, and we wanted to give it a jump start,” Gotfried said of the Saguaro Solar Power Plant.
The proposed plant would not necessarily use identical technology. But the figures give some perspective on the potential cost and size of a solar-thermal project that would generate 250 times the amount of energy as the Saguaro operation.
Keith Holbert, an associate engineering professor at Arizona State University who teaches a course on power plants, said solar-thermal plants offer utilities a better deal than solar panels, which are preferable for home use and smaller power plants.
Still, the amount of money to build a solar-thermal plant is about 4 1/2 times as expensive per kilowatt of electricity as a basic natural-gas plant, he said.
And solar plants are costlier to operate based on the amount of electricity they produce. Arizonans pay an average of less than 9 cents per kilowatt-hour of electricity, mostly produced at Palo Verde Nuclear Generating Station and several coal and natural-gas plants, according to the Energy Information Administration.
Solar-thermal, by comparison, costs about 20 cents per kilowatt-hour, depending on the system and local climate, Holbert said.
“Those costs will be passed on to the consumer. And how will the consumer feel about paying more for electricity?” he said. “It’s not going to mean our electricity price jumps or doubles, but we have to start paying a little bit.”
On the other hand, if the federal government ever decides to aggressively tax carbon emissions from traditional power plants as many environmentalists suggest, building a non-polluting solar plant makes more fiscal sense, he said.
Holbert said he thinks that is likely to happen in the next decade and nearly certain beyond that.
“Then, solar will look pretty attractive,” he said.