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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 51 to 75 out of 154:

  1. Michael sweet Florida has electricity at 10 cents per kwh. Believe it or not, you have subsidized electricity. Try joining the rest of us paying nearly twice that. I again make my single point that virtually all electricity is susidised to keep the price down for consumers. Do you agree virtually all electricity is subsidized? And please stop accusing me of claiming "hundreds of billions of dollars of subsidies".I didnt say that. I think you have the posts mixed up.
  2. "Do you agree virtually all electricity is subsidized?" Can I assume that is this only talking about the USA?
  3. @52 Places without subsidies a few and far between in or out of US. Your lquestion implies you know some. Would you like to share including the price?
  4. Michael Sweet If Florida pays $1bn subsidy to build a power plant, well that is only $52 per person living in Florida. I would be happy to pay a $52 subsidy if I could then get electricity for 10 cents per kwh like you do. I would recoup the $52 in about 2 months as I pay 21 cents per kwh.
  5. Realist: "The federal government provides hundreds of billions for renewable energy projects". It is a waste of my time to argue with someone who contradicts his own posts. What is your point? I have made mine that nuclear is uneconomic.
  6. Michael Sweet Thats a quote and obviously meant to be millions. My point is that virtually all electricity is subsidised. You cheery-picked that nuclear was uneconomic without a subsidy in Florida, when Florida ONLY pays 10 cents per kwh retail. But did you mention which sources of electricity would be economic at 10 c/kwh retail? No conveniently ommitted. Here is a link to Wikipedia for the cost of generation for the various sources. This is wholesale and excludes the costs for transmission, distribution, billing, marketing and profit. http://en.wikipedia.org/wiki/Cost_of_electricity_by_source
  7. Since these plans seem be over the longer term such as several decades, is it really a myth that "renewables can't provide baseload power" since they can't provide it now or in the short term? There are exciting new technologies coming out like vanadium redox batteries that seem to have the potential of solving the indeterminacy problem of wind and solar (and traditional power generation sources as well).
  8. Realist - I'm from NZ. Domestic electricity charges are around NZ$0.24 kWh. A bit of 50% is from hydro, ~11% from geothermal but wind is fastest growing sector. Gas is biggest part of the remaining thermal generation. For a country that espouses the free market so much, it's amazing the amount of subsidies that US citizen's tolerate.
  9. scaddenp, since we in the US have the highest corporate income tax rates of any large economy, our politicians are always subsidizing business via tax breaks in exchange for campaign donations. It's a much bigger problem than just the subsidies for producing CO2 like the 10:1 oil and gas to wind subsidy ratio. No, we don't like it, but there are a variety of political barriers to keep the system in place. (Note this is not a political post, I am pointing out the existence of a more general problem)
  10. "we in the US have the highest corporate income tax rates of any large economy" This is somewhat difficult to assess because of the complexities of tax laws. Nonetheless, it is most certainly false, as Japan has higher rates. Other countries are probably comparable in terms of what is actually paid, as there are myriads of ways to escape taxation in the convoluted US tax code.
  11. Philippe, I should have been clearer, the highest nominal rate, our complexity is basically a product of the favors (including subsidies) doled out, and you are right that the effective rate is often the same or less than other developed countries. But one piece of your information is 23 days out of date: Japan no longer has the highest nominal rate, see http://money.cnn.com/2012/03/27/pf/taxes/corporate-taxes/index.htm
  12. Eric - ours is 33% and no subsidies. I'd say the problem is elsewhere - time for the voter to get rid of them.
  13. scaddenp, please browse through this http://budget.house.gov/UploadedFiles/CRSR42374.pdf
  14. Good start. Just need to keep going.
  15. Before wanting subsidies removed, the electricity price is in an unsubsidized market should be considered as that will ultimately be the price. Even at 24 c/kwh in NZ, I doubt that is without subsidies.
  16. Realist - why do you say that? Where is the evidence of any subsidy? In the '80s and '90, economic reform here screamed about level playing fields and any form of business subsidy became a dirty word. Health care and education get subsidies and there are some schemes for getting government contribution to research, but nothing for generation and delivery of electricity. I'd say there was evidence that dumping subsidies doesnt send electricity costs through the roof (and your taxes go down - or would if your government could balance its books). If you feel that you must subsidize electricity on social grounds then put subsidy on the delivery so all forms of generation are on an equal footing.
  17. There are hundreds of ways of subsidizing, or externalising costs. For the hydro, who paid for the dam, the land the dam is on, the land the power station is on, the transmission lines, the land the transmission lines are on, the roads, the water costs, the compensation for flooded farms etc. For the gas power station, do the gas producers pay full taxes on gas provided to powers stations, or do the gas producers have an obligation to provide gas to power stations at a defined and reduced cost as part of their approvals with the government? In Australia green energy is cross subsidized by power companies having a mandatory renewable energy target, so they pay the subsidy by installation rebates and feed in tariffs as high as 66 cents/kwh. So subsidies can be well hidden. The point is if you remove subsidies, you change the economics of supply, whic means you move on the supply-demand curve and get a new price equilibrium. The other way of looking at it is, what is the role model country for electricity generation and do they have subsidies and what is their cost?
  18. If a generating company wants to build a hydro, windfarm, etc. then they must buy the land and build it unaided, and raise capital in normal way. You can only make money from say a wind turbine if your price is competitive enough to bid into the market. Transmission costs ($0.17/kwh) are passed to directly to consumer. While a government owned company, the transmission provider has to raise capital with bonds, pays tax at company rate and dividends on profit. What is coming into play slowly is effectively a "subsidy" on non-carbon generation - the Emission Trading Scheme. However, renewables were more than competitive with coal/gas before it arrived. Also, emitters were given credit for current rate of emission, the ETS so far only counts against expanding carbon-generating emissions. The clear message here is that government is doing its level best to ensure there are no direct or indirect subsidies.
  19. #68 Despite looking, I have not found any country where that electricity market financial model actually exists ie zero subsidies during development or during operations. Are you aware of its existence? Nor aware what is/would be the electricity tariff under in unsubsudised market? Would be rather high.
  20. So where are the subsidies in New Zealand? That is what I am pointing out. ETS only came into play few years ago if you are regarding that as "subsidy". Not that relevant as no new carbon-burning generation has been built since.
  21. Oh, and ETS increases cost of power to consumer, not decrease it. Where is your evidence that $0.24/kwh is not the unsubsidized price?
  22. #71 You really think its not subsidized? These are deals companies make before they will build a new plant. In Australia there are even special government departments whose only job is to come up with deals to get industries to invest. No company is stupid enough to build a new power station without a deal. They don't have to invest in NZ, they can take their money and invest where they will get a deal. Its all done under confdentiality agreement. No subsidy Is the equivalent of someone paying full price for a new car. Doesn't happen (except for the very stupid).
  23. Realist, you keep insisting on this. You seem to have taken an a priori position that electricity must be subsidized to provide a particular price and are uninterested in other evidence. NZ companies are building new generation to meet demand and do so because they believe they can make a profit in the current market. Demand is increasing, there is no price control so why not. The government does not do deals. Your insistence that does without a scrap of evidence is not convincing.
  24. It's worth noting too that Australia didnt go through NZ-style economic reforms in 80s, 90s so things are done differently. With economic "drys" in command in both parties over that period, NZ is a different place. I dont buy the idea that generation isn't built without a deal. If no generation is build, electricity price would soar - if a company doesnt move to catch that profit, then a competitor will. A variety of companies are building new generation.
  25. Where should I go to understand the following issue? Say one wished to generate serious solar power for the U.S. Then if one covered 7.5% of Arizona's land area with photovoltaics of 15% efficiency you could probably generate all U.S. electrical needs. (Wolfson, "Energy, Environment, and Climate", 2nd edition, p. 251.) (Granted you would do better with a concentrating system in terms of land area, but that is not my basic issue.) My question is: If you wanted to get desert electricity to New York City, which is part of the Eastern Interconnection Subgrid, would you not need to build something quite different or in addition to, the existing grid? At the very least, high voltage D.C. transmission? Or does such a connection presently exist? Although political comments will be deleted, perhaps it would be o.k. for me to say that I can document thoroughly what a political nightmare it would be to obtain any upgrade for the Grid system in the U.S. It is not just the cost.

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