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Can renewables provide baseload power?

What the science says...

Select a level... Intermediate Advanced

Although renewable energy does not necessarily need to provide baseload power in the short-term, there are several ways in which it can do so. For example, geothermal energy is available at all times, concentrated solar thermal energy has storage capability, and wind energy can be stored in compressed air.

Climate Myth...

Renewables can't provide baseload power

Does Renewable Energy Need to Provide Baseload Power?

A common myth is that because some types of renewable energy do not provide baseload power, they require an equivalent amount of backup power provided by fossil fuel plants.  However, this is simply untrue.  As wind production fluctuates, it can be supplemented if necessary by a form of baseload power which can start up or whose output can be changed in a relatively short period of time.  Hydroelectric and natural gas plants are common choices for this type of reserve power (AWEA 2008). Although a fossil fuel, combustion of natural gas emits only 45% as much carbon dioxide as combustion of coal, and hydroelectric is of course a very low-carbon energy source.

The current energy production structure consists primarily of coal and nuclear energy providing baseload power, while natural gas and hydroelectric power generally provide the variable reserves to meet peak demand. Coal is cheap, dirty, and the plant output cannot be varied easily.  It also has high initial investment cost and a long return on investment time.  Hydroelectric power is also cheap, clean, and good for both baseload and meeting peak demand, but limited by available natural sources.  Natural gas is less dirty than coal, more expensive and used for peak demand.  Nuclear power is a low-carbon power source, but with an extremely high investment cost and long return on investment time.

Renewable energy can be used to replace some higher-carbon sources of energy in the power grid and achieve a reduction in total greenhouse gas emissions from power generation, even if not used to provide baseload power.  Intermittent renewables can provide 10-20% of our electricity, with hydroelectric and other baseload renewable sources (see below) on top of that. Even if the rapid growth in wind and other intermittent renewable sources continues, it will be over a decade before storage of the intermittent sources becomes a necessity.

Renewable Baseload Energy Sources

Of course in an ideal world, renewable sources would meet all of our energy needs.  And there are several means by which renewable energy can indeed provide baseload power. 

Concentrated Solar Thermal

One of the more promising renewable energy technologies is concentrated solar thermal, which uses a system of mirrors or lenses to focus solar radiation on a collector.  This type of system can collect and store energy in pressurized steam, molten salt, phase change materials, or purified graphite.  

The first test of a large-scale thermal solar power tower plant was Solar One in the California Mojave Desert, constructed in 1981.  The project produced 10 megawatts (MW) of electricity using 1,818 mirrors, concentrating solar radiation onto a tower which used high-temperature heat transfer fluid to carry the energy to a boiler on the ground, where the steam was used to spin a series of turbines.  Water was used as an energy storage medium for Solar One.  The system was redesigned in 1995 and renamed Solar Two, which used molten salt as an energy storage medium.  In this type of system, molten salt at 290ºC is pumped from a cold storage tank through the receiver where it is heated to about 565ºC. The heated salt then moves on to the hot storage tank (Figure 1).  When power is needed from the plant, the hot salt is pumped to a generator that produces steam, which activates a turbine/generator system that creates electricity (NREL 2001).

 

Figure 1:  Solar Two Power Tower System Diagram (NREL 2001)

The Solar Two molten salt system was capable of storing enough energy to produce power three hours after the Sun had set.  By using thermal storage, power tower plants can potentially operate for 65 percent of the year without the need for a back-up fuel source. The first commercial concentrated solar thermal plant with molten salt storage - Andasol 1 - was completed in Spain in 2009.  Andasol 1 produces 50 MW of power and the molten salt storage can continue to power the plant for approximately 7.5 hours.

Abengoa Solar is building a 280 MW solar thermal plant in Arizona (the Solana Generating Station), scheduled to begin operation in 2013.  This plant will also have a molten salt system with up to 6 hours worth of storage.  The electrical utility Arizona Public Service has contracted to purchase the power from Solana station for approximately 14 cents per kilawatt-hour. 

Italian utility Enel recently unveiled "Archimede", the first concentrated solar thermal plant to use molten salts for both heat storage and heat transfer.  Molten salts can operate at higher temperatures than oils, which gives Archimede higher efficiency and power output.  With the higher temperature heat storage allowed by the direct use of salts, Archimede can extend its operating hours further than an oil-operated solar thermal plant with molten salt storage.  Archimede is a 5 MW plant with 8 hours of storage capacity.

In southern Spain, the Gemasolar plant opened in 2011.  It produces 19.9 MW, or approximately 110 gigawatt-hours per year.  Gemasolar stores energy in molten salt for up to 15 hours, and is thus able to provide energy 24 hours per day for a minimum of 270 days per year (74% of the year).

The National Renewable Energy Laboratory provides a long list of concentrated solar thermal plants in operation, under construction, and in development, many of which have energy storage systems.  In short, solar thermal molten salt power storage is already a reality, and a growing resource.

Geothermal

Geothermal systems extract energy from water exposed to hot rock deep beneath the earth's surface, and thus do not face the intermittency problems of other renewable energy sources like wind and solar.  An expert panel concluded that geothermal sources could produce approximately 100 gigawatts (GW) of baseload power to the USA by mid-century, which is approximately 10% of current US generating capacity (MIT 2006).  The panel also concluded that a research and development investment of less than $1 billion would make geothermal energy economically viable.

The MIT-led report focuses on a technology called enhanced or engineered geothermal systems (EGS), which doesn't require ideal subsurface conditions and could theoretically work anywhere.   installing an EGS plant typically involves drilling a 10- to 12-inch-wide, three- to four-kilometer-deep hole, expanding existing fractures in the rock at the bottom of the hole by pumping down water under high pressure, and drilling a second hole into those fractures.  Water pumped down one hole courses through the gaps in the rock, heats up, and flows back to the surface through the second hole. Finally, a plant harvests the heat and circulates the cooled water back down into the cracks (MIT 2007).

Currently there are 10.7 GW of geothermal power online globally, with a 20% increase in geothermal power online capacity since 2005.  The USA leads the world in geothermal production with 3.1 GW of installed capacity from 77 power plants (GEA 2010).

Wind Compressed Air Energy Storage (CAES)

Various methods of storing wind energy have been explored, including pumped hydroelectric storage, batteries, superconducting magnets, flywheels, regenerative fuel cells, and CAES.  CAES has been identified as the most promising technology for utility-scale bulk wind energy storage due to relatively low costs, environmental impacts, and high reliability (Cavallo 2005).  CAES plants are currently operational in Huntorf, Germany (290 MW, since 1978) and Macintosh, Alabama (110 MW, since 1991).  Recently this type of system has been considered to solve the intermittency difficulties associated with wind turbines.  It is estimated that more than 80% of the U.S. territory has geology suitable for such underground storage (Gardner and Haynes 2007).

The Iowa Stored Energy Park has been proposed to store air in an underground geologic structure during time periods of low customer electric demand and high wind.  The project is hoping to store a 20 week supply of compressed air and have approximately 270 MW of generating capacity.  The project is anticipated to be operational in 2015. 

A similar system has been proposed to create a wind turbine-air compressor.  Instead of generating electricity, each wind turbine will pump air into CAES. This approach has the potential for saving money and improving overall efficiency by eliminating the intermediate and unnecessary electrical generation between the turbine and the air compressor  (Gardner and Haynes 2007).

Pumped Heat Energy Storage

Another promising energy storage technology involves pumping heat between tanks containing hot and cold insulated gravel.  Electrical power is input to the system, which compresses/expands air to approximately 500°C on the hot side and -150°C on the cold side. The air is passed through the two piles of gravel where it gives up its heat/cold to the gravel. In order to regenerate the electricity, the cycle is simply reversed.  The benefits of this type of system are that it would take up relatively little space, the round-trip efficiency is approximately 75%, and gravel is a very cheap and abundant material.

Spent Electric Vehicle (EV) Battery Storage

As plug-in hybrids and electric vehicles become more commonplace, the possibility exists to utilize the spent EV batteries for power grid storage after their automotive life, at which point they will still have significant storage capacity.  General Motors has been examining this possibility, for example.  If a sufficiently large number of former EV batteries could be hooked up to the power grid, they could provide storage capacity for intermittent renewable energy sources.

100% Energy from Renewables Studies

A few studies have put forth plans detailing exactly how we can meet 100% of global energy needs from renewable sources.

Energy consulting firm Ecofys produced a report detailing how we can meet nearly 100% of global energy needs with renewable sources by 2050.  Approximately half of the goal is met through increased energy efficiency to first reduce energy demands, and the other half is achieved by switching to renewable energy sources for electricity production (Figure 2).

ecofys fig 1

Figure 2: Ecofys projected global energy consumption between 2000 and 2050

Stanford's Mark Jacobson and UC Davis' Mark Delucchi (J&D) recently published a study in the journal Energy Policy examining the possibility of meeting all global energy needs with wind, water, and solar (WWS) power.  They find that it would be plausible to produce all new energy from WWS in 2030, and replace all pre-existing energy with WWS by 2050

In Part I of their study, J&D examine the technologies, energy resources, infrastructure, and materials necessary to provide all energy from WWS sources.  In Part II of the study, J&D examine the variability of WWS energy, and the costs of their proposal.  J&D project that when accounting for the costs associated with air pollution and climate change, all the WWS technologies they consider will be cheaper than conventional energy sources (including coal) by 2020 or 2030, and in fact onshore wind is already cheaper. 

Summary

To sum up, there are several types of renewable energy which can provide baseload power.  It will be over a decade before we can produce sufficient intermittent renewable energy to require high levels of storage, and there are several promising energy storage technologies.  One study found that the UK power grid could accommodate approximately 10-20% of energy from intermittent renewable sources without a "significant issue" (Carbon Trust and DTI 2003).  By the time renewable energy sources begin to displace a significant part of hydrocarbon generation, there may even be new storage technologies coming into play.  The US Department of Energy has made large-scale energy storage one if its research priorities, recently awarding $24.7 million in research grants for Grid-Scale Rampable Intermittent Dispatchable Storage.  And several plans have been put forth to meet 100% of global energy needs from renewable sources by 2050.

Last updated on 4 November 2016 by dana1981. View Archives

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Comments 26 to 50 out of 102:

  1. The projected energy consumption, the dotted line, appears too low. The population from 2000 to 2050 is to grow from 6 bil to about 10 bil. However the middle classing of India and china will be a large energy demand increase. There is not enough focus on hydro. Hydro can produce large amounts of electricity on any day you choose, but not every day as the water will run out. As a backup for wind or solar PV, when it has been cloudy for days and the storages are depleted, or there has been unusually light winds over large areas, the hydro can reliably fill the gap. It is the only large scale energy storage system that is currently commercialized, and has been for decades.
  2. Hydro can provide reliable cheap power but this is very dependent on site. In NZ, there are very few large scale sites left, even fewer cheap ones. I imagine the situation is similar in many other countries. You need large reliable water volume (easy) and substantial fall (tough) on a site with cheap construction.
  3. Hydro can be a power source or energy storage system. For energy storage water is pumped from a low level dam to a high level dam when there is excess power, say with solar PV during the day, and then used to generate power in the evening by running the water back to the low level dam. Of course the measure for all energy storage systems is what percentage of the energy do you get back, and what are losses during holding. Hydro has very low holding lossess. You can store it for 12 months and only lose a little to evaporation and seepage.
  4. My local paper had an article on financing a nuclear power plant. It is only possible because the local ratepayers must pay 10 years in advance of receiving the power and the power company makes 15% even if the plant is never built. They stand to profit $150 million now and they have not even applied for a permit to build yet. If that is the only way to finance nuclear it is not economic.
  5. I read Archer and Jacobson and their argument has a critical flaw. A&J stated that coal fired power had an availability of 87.5% and compared this with the availability that a wind power network of 19 interconnected sites spread across midwest USA can achieve. The comparison benchmark for availability for wind to achieve in the report became 87.5%. The critical flaw in the argument is that 87.5% is the availability of a single coal fired generator, it is not the availability of a coal fired power network!! So they are comparing a wind network with a single coal fired generator. How something like that passed peer review is astounding. If you still have any doubt that 87.5% availabilty is incorrect, well this would mean householders supplied by coal power would have blackouts for 1095 hours per year (12.5% x 365.25 days x 24 hours) Those households who have coal fired power would typically have blackouts less than 8 hrs per year, thats 99.9% availabilty, because the coal fired units are also interconnected and they have excess generators running at any time to pick up the load if one generator trips. If you refer to the A&J chart of "Generation duration curves for arrays", for 99.9% availability and 19 sites this means the available power per generator is about 30 kW, it does not give the about 250kW that 87.5% would imply. A significant difference!!
  6. Michael Sweet @29. I read the article you linked, but you really shouldnt blame the nuclear power company, you should blame the legislators you voted for that signed the contract you consider bad. Having said that, it is not uncommon for governments to make contributions to all sorts of large projects, because without a contribution the project may not be viable without charging more for their product, and most governments try to keep utility prices down.
  7. Realist, Who made the bad deal is not the question. Big energy has political friends, is this a surprise? The point is that if nuclear power plants require this type of financing they are not economic. This project is likely to be stopped in the near future, it is not economic and people are starting to get angry about high prices for energy we will never receive.
  8. Michael Sweet No its not a surprise that the governments have political friends, but someone must have voted for these guys who signed the bad contract? Virtually all electicity infrastructure is subsidised somehow, not just nuclear. Wind and solar presently get very high subsidies in many parts of the world and probably in Florida too. Comparing subsidies on the basis of MW.hr per year generated (not installed eg include availability), then hundreds of millions dollars for what is probably a 1000 MW plant is much lower than wbhat I have seen as typical wind and solar subsidies eg in Germany and in Australia.
  9. "Virtually all electicity infrastructure is subsidised somehow, not just nuclear" And that applies to hydro, coal and natural gas as well. Yet the companies running it do so as if it was entirely their own and the taxpayers who made them possible in the first place have a say in prices that amounts to, what exactly? Wind and solar need and deserve subsidies, their renewable character alone earns them that. Coal, oil and gas get subsidies based on what premise? That they're too expensive to be set up by a purely private venture? That they'll have a hard time to make profits? And then they're run as if they were private once built. Please. The belly aching about subsidies is just the weakest argument one can possibly make in this debate. I'll pay attention to that argument once all subsidies for oil, coal and gas are killed. Politics being what they are, that's not happening any time soon. Yes people voted for the guys who signed the contracts, after having their minds thoroughly manipulated by, guess what, private companies that specialize in mind manipulation. And considering the citical thinking abilities and Dunning-Kruger effect we get to see at work just on this site, these companies have their work cut out for them. The representative republic principles met their limits long ago, as human duplicity knows no bound. Now the circus has taken over. Enjoy.
  10. @33 Interesting how of the nine lines I wrote you only responded on one. You asked on what premise electricity infrastructure is subsidised? The answer was in my previous post:- "Having said that, it is not uncommon for governments to make contributions to all sorts of large projects, because without a contribution the project may not be viable without charging more for their product, and most governments try to keep utility prices down." You need to consider subsidies in conjunction with the royalties. With oil gas and coal the subsidies are insignificant compared to the royalties and taxes paid. Governments know that any subsidy paid they will get back many times over. Of course the companies run it as if it was private even if they received a subsidy, the same way someone who gets a first home buyers grant considers the house is their own and not the governments. Thats just a red herring. "Private companies that specialise in mind manipulation" Huh? Could you please back up your claim with the names of some of these companies?
  11. #35: How does "without a contribution the project may not be viable without charging more for their product, and most governments try to keep utility prices down" square with some of the largest corporate profits on the planet. It's not as if Exxon is going to go bust even if it reduced it's profits by the GDP of several small African countries...
  12. @36 Well Exxon doesnt build power stations so your post is not related to the conversation at the time of my comment. But if you want to complain about resource company profits then blame legislators who haven't negotiated sufficient royalties, and ahem, the voters who put them there! Remember petroleum royalties are an absolute cash cow for many governments and keep some countries afloat. So a transition to renewables will need alternative income sources for many governments and countries, which to date has not been widely discussed.
  13. #37, my comment was in response to part of #35 and related to #34, neither post by you, and hardly unrelated to the conversation? Petroleum royalties are a cash cow - because they are the dominant form of energy we presently use. Do you think that energy, when supplied entirely from non-FF sources, will be untaxed?
  14. #38 No I don't think there will be royalties on most non-ff energy sources. I don't think for instance that there will be a royalty to the government for wind or solar, perhaps something like geothermal might if there is a prime plot it land for the highest bidder. As for tax, well that is after depreciation and the depreciation will wipe out taxable profit for a long time. But that results in a massive black hole for the revenue of many countries eg Nigeria, libya, venuzela, the middle east and USA.
  15. Realist, The project that I linked to alone has received over $1 Billion in subsidies and has not delivered a single watt. It is unlikely to ever generate any power. Nuclear in Florida received much more in subsidies on any basis than renewables. This is a concrete example of nuclear power that is not economic at any price. In Texas they are building a lot of wind. I doubt Texas is subsidizing wind. If you want to argue that renewables are subsidized more than renewables you must give a concrete example against the one I have produced. Hand waving and saying "probably in Florida too." is not an argument.
  16. Michael Sweet #40 Its difficult to find an electricity project that isnt subsidised somehow. $1BN for the nuclear plant. Lets Google Florida... Ahh Florida electricity is about 10 cents per kwh. Wow thats about the cheapest in the world. For a comparison, Germany is 23 cents per kwh, partially because of all the solar, and Austrialia is 21 cents. No wonder no company wants to build an electricity plant in Florida without huge subsidies. The alternative is to allow shortages of electricity to push up the price of electricity until it is viable to build a power plant without subsidies. As for if Texas gets wind subsidies, you betcha! A very quick Google search found the following. Note $1.3BN from 2009 to 2010, unlike the one-off $1BN for your nuclear plant, the wind guys in Texas want this level of subsidy every year... http://energyandenvironmentblog.dallasnews.com/archives/2010/12/wind-industry-says-3000-texas.html "Wind industry says 3,000 Texas jobs could be lost if key subsidy isn't renewed" 11:51 AM on Wed., Dec. 8, 2010 "The wind industry says it's mobilized to lobby Congress to extend a key subsidy that kept the business going during the recession. Despite having White House support, the program was left out of an agreement announced this week that would extend the Bush tax cuts, unemployment insurance, and a host of other incentives. It has sent more than $1.3 billion to wind-energy projects in Texas since 2009."
  17. Michael Sweet #40 As for the subsidy for wind being higher than FF, and you mentioned Texas... http://www.texaspolicy.com/pdf/2011-WindEnergy-CEF-CEE.pdf "Subsidies for wind are one source of these costs. Although most energy sources receive some government subsidies, the subsidies for renewable energy sources are far higher on a per unit of production basis than traditional sources of energy. At $23.37 per MW hour, wind receives 100 times the federal money that natural gas generation receives. The federal government provides hundreds of billions for renewable energy projects, including grants for 35 percent of construction cost."
  18. Re: subsidies. One measurement of subsidies is how much the taxpayer pays versus how much the ratepayer pays. The Texas taxpayer pay very little in subsidies for wind power, and ratepayers pay a very low 11-12 cents per kWh for all sources. Part of the reason is that Texas wind picks up some Federal subsidies. It is all detailed in this report: http://www.window.state.tx.us/specialrpt/energy/subsidies/
  19. Realist: "The federal government provides hundreds of billions for renewable energy projects," This is obviously a false statement. The federal government does not provide hundreds of billions of dollars for all renewables combined. Provide a reliable source for this absurd claim. Please provide data from a peer reviewed source, not a right wing think tank. Find a single renewable project that has received $1 billion dollars of subsidy. I have provided an example of such a nuclear facility. They have received $1 billion dollars of subsidy and it has not even started construction yet! You cite right wing propaganda against my specific example.
  20. Realist: Your citation for the supposed $1.3BN for wind does not list how the money is paid out. As I recall, those are production tax credits. The coal and oil industries get massive tax credits that you have not mentioned. Citing incomplete, right wing propaganda in newspapers does not make a believable argument. Provide a specific example against my $1Bn nuclear example. The nuclear plant has not yet started construction.
  21. Well subsidies are a dirty word here, on anything. Wind power gets built without it. Coal, not so much. Electricity generation at 75% renewable and well on track for 80% by 2020.
  22. Michael sweet If you have an interest in the breakdown of subsidies, I suggest you do your own research. Note that you have not given a breakdown of the massive coal subsidies you mention but expect others to provide breakdowns for you. Now is that fair? However I suggest you start with the excellent link by Eric @43, it's very informative.
  23. Realist, According to Eric's link (the state of Texas), coal is subsidized at 6.9%, nuclear at 21%, wind at 12% and solar at 12%. Since coal and nuclear are mature industries that should receive no subsidies. It is clear that wind and solar are doing well for new industries and their government subsidies are reasonable. This reference states less than 1Bn subsidies total in the US for both wind and solar. They do not count the Florida subsidy of nuclear, because it is paid by the customers and not the government. I imagine that Texas would exaggerate the subsidy of wind and solar and underestimate fossil fuel subsidies. The fact is that investors will not build nuclear because it is not economic. They are not building coal because there is not enough coal supply to provide coal for the length of the life of a new coal powered generator. Wind and solar are dropping rapidly in price even without much government support. Your claim of "hundreds of billions" of subsidies is so much crap, as are your right wing references. Provide some real data to support your wild claims.
  24. Michael sweet Just recapping:- Your post was that the florida nuclear plant was subsidized and you believed it shouldnt be. My point was that virtually all electricity is subsidized so that the electricity cost to consumers is kept down. Your point was that you didnt think wind in Texas would be subsidized. I came back with an article that the wind industry in Texas wants the $1bn in a year subsidy to continue. You have now read the link by Eric and quoted the subsidies for the different forms of energy. I take that as you acknowledge the subsidies for electricity are widespread and across the different forms of electricity production. I am not clear what your point is. Can you please be concise as to what it is?
  25. Realist, My point, as I stated in my first post, was that nuclear power appears to be uneconomic. You have not produced any useful references. Eric's post states that the entire wind industry in the USA receives less than 500 million per year. Your claim of 1Bn/yr for Texas alone is false (as was your claim of "hundreds of billions"). I cited a single nuclear plant that has received over 1Bn in subsidies (over several years). It is not clear what your point is. Renewables receive less subsidies than established power industries in the USA, which is backwards from what should happen. The OP in this thread discusses whether renewables can produce baseload power. You have produced nothing to support your apparent claim that renewables will not be able to handle all power needs in the future.

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