Solar Thermal Electricity: Can it Replace Coal, Gas, and Oil?
Written by Sarah Lozanova
One of the most common arguments against large-scale use of renewable energy is that it cannot produce a steady, reliable stream of energy, day and night. Ausra Inc. does not agree. They believe that solar thermal technology can supply over 90% of grid power, while reducing carbon emissions.
“The U.S. could nearly eliminate our dependence on coal, oil and gas for electricity and transportation, drastically slashing global warming pollution without increasing costs for energy,” said David Mills, chief scientific officer and founder of Ausra.
You may be wondering, how will we have electricity at night or during cloudy weather?
Will we use large banks of batteries or burn candles?
The ability to utilize solar thermal technology after the sun sets is made possible by a storage system that is up to 93% efficient, according to Ausra’s executive vice president John O’Donnell.
High efficiency is achieved because solar thermal plants do not need to convert energy to another form in order to store it and do not rely on battery technology. Flat moving reflectors or parabolic mirrors focus solar energy to generate heat. This heat generates steam that turns turbines, thus generating an electric current.
If you want to generate electricity-at, say, 3 am-heat from the sun can be stored for later use. This gives solar thermal technology the ability to not just produce peak power, but also generate base load electricity.
Peak Power: The First Wave of Solar Thermal Plants
The maximum amount of electricity demand on the power grid occurs during weekday afternoons and evenings in the summer months in most regions of the United States. This is largely caused by air conditioning loads, which gobble up electricity.
Because the electric grid needs to be able to handle these peak loads, capacity is built to specifically handle these loads. Natural gas and oil typically comes to the rescue to produce this electricity. Although these plants are expensive to operate, they are cheaper to construct than most of the alternatives. They are fast to start, producing power in 30 minutes or less. Additional power plants are constructed just to generate electricity for the times when it is needed most.
This causes peak electricity to be more expensive. A kilowatt hour of electricity at 3 pm and 3 am does not come with the same price tag to the utility company.
“Adding solar plants that reliably generate until 10 pm displaces the highest cost alternative power,” said John O’Donnell. “That is the first wave of solar thermal plants. The daily and seasonal variation in grid load in the United States matches solar availability.”
Base Load: Replacing Coal Power
Base load is the minimum amount of electricity demand placed on the power grid over a 24 hour period. Coal and nuclear plants commonly supply this energy. These plants can take hours or even days to heat up to operating temperatures and are run more continuously than peak power plants.
Due largely to the lower cost of fuel, these plants can produce electricity at a lower cost. If a carbon tax is implemented in the future, this will increase the cost of electricity generated from coal.
Generating electricity around the clock with solar thermal technology relies on storage systems that run turbines long after the sun sets. “Ausra has a very active energy storage R & D group and we will be prototyping a couple of systems this year here in the US,” said John O’Donnell.
Solar Energy Storage
This is not a new technology, having been used for plastic manufacturing and petroleum production for a long time. Solar thermal plants have a cost advantage compared to photovoltaic technology because energy can be stored as heat without being converted to another form or relying on batteries.
“My favorite example in comparing energy storage options is on your desktop,” said John O’Donnell. “If you have a laptop computer and a thermos of coffee on your desk, the battery in your laptop and the thermos store about the same amount of energy. One of them costs about $150 and the other one costs maybe $3 to $5. On the wholesale level, storing electric power is at least 100 times more expensive than storing heat.”
The future certainly looks bright for solar thermal technology as concern over climate change increases. Global demand for electricity is growing rapidly, requiring clean solutions.
Sarah Lozanova is a freelance writer that is passionate about the new green economy and is a regular contributor to environmental and energy publications and websites, including Energy International Quarterly, ThinkGreen.com, Triple Pundit, Green Business Quarterly, Renewable Energy World, and Green Business Quarterly. Her experience includes work with small-scale solar energy installations and utility-scale wind farms. She earned an MBA in sustainable management from the Presidio Graduate School and is a co-founder of Trees Across the Miles, an urban reforestation initiative.
Very nice post solar technology, its my pleasure that i read your this post.
Thanks.
Thanks for your article. I hope you’re right about “The future certainly looks bright for solar thermal technology.” I work with Sharp and have been doing some research into solar electricity. Since most electricity is generated by burning coal, resulting in it being environmentally released into the atmosphere, solar energy, as a clean and renewable energy source, would greatly reduce the danger to the environment. Sharp offers free solar consultations. It’s important to do your own research if you are considering going solar. solar electricity
I’ll believe when I see it……
Randy
Randy,
Check it out! This is your future, or at least that of young minds that see a clean energy future. Without getting political, you’ve got to agree that you are working in an antiquated technology. Why do you have to fight so hard against the idea of human evolution, educating science students everywhere, and moving towards a real boon for mankind – Where we can use the fruits of electricity, without all the pitfalls? Is that really something that you want to align yourself against? Really?
Rich,
I didn’t speak out against it…….I just said I would believe it when I see it.
I’ve had several Physics classes and I understand energy generation and efficiency. I just want to SEE it.
Randy
Randy,
I’m glad that you aren’t speaking out against it, like some others have here. I am excited that some companies are investing their future in technology that fosters a clean future. That IS the future. Why do supporters of coal have to call names, and be so mad at those who are trying to ask for support for these sorts of energy policies? That’s what our fathers fought and died for, the freedom to speak out. I understand that you have your job to think about, and it’s not all black and white, as I’ve said before… No one that wants a new energy policy and a stop to MTR, and coal fired electric plants wants to take away jobs. They want to create a world where technology sparks many new opportunities that we’ve never even thought of yet.
You WOULD see it, if there was support politically for more of this sort of thing. You will see it, hopefully in short order. Then you wouldn’t have to be a part of the destruction of the Appalachians, or an industry that puts profits before people.
Rich,
Just to keep the record straight. Were you referring to me? When you said “like some others have here”.
If the shoe fits…
I thought it was and I don’t really have a problem with it. It just shows everyone that your reading what you want to hear and not what is bing said.
Rich, I challenge you to go back through my posts and show me where I’ve ever said anything against wind, solar or any other alternative form of energy. In fact I think you’ll find the opposite, on more than one occasion I have stated that I want the USA to be energy independent which includes all forms of energy gas, oil, coal, nuclear, wind, solar etc. My main concern is and has been that the enviro loons want to put an immediate stop to surface mining, however the way the EPA is going about it will adversly affect all forms of mining in Appalachia. We all know that as of today we do not have the infrastructure inplace to replace the amount of coal that is being used. That is not to say we never will, most so called experts think it will be 25 years or so before wind and solar power is a viable option.
You need to open your eyes, this country has to maintain a certain amount of electricity. What is going to happen when you take 90% of Kentucky’s and West Virginia energy source and try to replace it with wind and solar electricity which only accounts for 2% of our electricity? The same goes for the country which receives nearly 50% of it’s electricity from coal. The numbers simply do not add up.
“If it does not fit, you must acquit.” – Johnnie Cochran in defense of O.J. Simpson
“The truth will set you free” – Aunt Ester on Sanford and Son.
Free at Last! Free at Last! Thank God Almighty, We are free at last! – Martin Luther King
Dear Sarah,
I work as an engineer in a gas fired power plant. Heat energy can be stored but turbines will not accept variations more than +- 50 deg C of the working fluid viz steam . Even with the best insulation,this variation is inevitable during nightime.