Wind Turbines Waste Much Less Energy Than Fossil Fuels


mcdlttx, via Flickr

by Zoë Casey, via Renewable Energy World

Wind energy opponents who say that producing electricity using the power of the wind is not efficient would do well to take a look at a new graphic published on the Guardian’s data blog using UK Government data. ‘Up in smoke: how energy efficient is electricity produced in the UK?’ shows that thermal sources of electricity – gas, coal, nuclear, waste/biomass, oil and other – lose massive amounts of energy as waste heat, compared to almost 0% for renewables.

Gas accounts for 48% of the UK’s electricity supply and, of the 372 Terra-Watt hours of electricity it produces per year, 54% of this is lost as heat. Coal, meanwhile, accounts for 28% producing 297 TWh, loses an even higher proportion – 66%. Nuclear – accounting for 16% of the energy supply with 162 TWh, loses 65% and oil – 3% of the supply with 51 TWh – loses 77%.

Contrast these figures with renewable energy – which all together account for 4% of the UK’s electricity supply producing 14 TWh – they lose less than one percent. So, under this measure, renewable energy is 100% efficient.

Wind energy opponents centre their arguments on the ‘capacity factor’ of a wind farm. The capacity factor of any power plant is a measure of the amount of energy it actually generates compared to its theoretical maximum output in a given time. No power plant operates at 100% of its capacity.

Wind farms do not operate at wind speeds of less than 4 metres per second, and they are shut down to prevent damage during gale force winds of 25 metres/second or more, or for maintenance. But conventional power stations also do not operate all the time – they stop generating electricity during maintenance or breakdowns.

Comparing the outputs of both sources does show that conventional power stations produce power at a level compared to their theoretical maximum that is currently higher than the level for wind energy. Wind power’s capacity factor is around 30% onshore and 40% offshore, increasing year on year as more wind turbines come online and technology improves. Meanwhile, data from the German Association of Energy and Water Industries (Bundesverband der Energie und Wasserwirtschaft) shows that fossil fuels are often below 50%, even in winter.

RenewableUK, the national industry body, says that the UK has one of the best wind regimes in the world and wind turbines have considerably higher capacity factors than many of the European countries where wind already makes a significant contribution to electricity supplies. Denmark, for example, has a wind farm capacity factor of 24% and yet wind power ‘fuels’ over a quarter of its electricity supply.

Zoë Casey is the Communications director and blog editor for the European Wind Energy Association. This piece was originally published at Renewable Energy World and was reprinted with permission.

19 Responses to Wind Turbines Waste Much Less Energy Than Fossil Fuels

  1. Paul Klinkman says:

    The measuring stick with the most integrity would be total carbon released during a wind turbine’s or a coal plant’s life cycle, including any extra wires strung and energy storage (pumped hydro), versus power consumed. Yes, wind power is still going to win handily.

  2. Joan Savage says:

    That’s something to bring to the attention of the energy chart makers at Lawrence Livermore National Laboratory. As it is at present, the waste energy ratio is lumped together by use, not source.

  3. Doug Bostrom says:

    “Not efficient?”

    Huh. I guess the Sun is a failure; the Sun only works intermittently for anybody living on Earth.

  4. alex says:

    Agreed. the wind was going to blow anyhow, so it’s specious to measure efficiency except at design conditions. I still think photovoltaics will rule, as we get many times the power demand and they can cool the local area while taking that free resource. Conventional systems all spew waste heat as well as other pollutants, greenhouse &/or extreme toxics.

  5. RankineCycle says:

    The word “efficiency” is one the most misused words on earth. It’s nice because it can be tailored to meet an agenda.

    Let’s say for example that Springfield Nuclear Power Plant has a 95% electrical efficiency, 33% thermodynamic efficiency, 80% capacity factor, and 2% burnup of fuel in the core. The distribution lines to Homer Simpson’s house have a 90% efficiency, and the incandescent light bulbs the Simpsons use in their home have a 3% efficiency in summer (5% if they don’t run the air conditioning) and a 100% efficiency in winter.

    Depending on my cultural, political, or economic agenda I can cherry pick numbers. If I were anti-nuke I’d pick the 2% burnup rate. If I were pro-nuke, I’d pick the 80% capacity factor. If I were Areva, I’d tell Mr. Burns how a new steam generator will bring his turbines up to 37% efficiency. If I were GE, I’d tell Springfield that my new Smart Grid technology will cut their distribution losses in half. If I were Philips Lighting, I’d tell the Simpsons how bad their lights were so they’d buy my LEDs. If I were selling rabid fear of the Illuminati trying to take away my light bulbs, I’d speak of how they heat my home in the winter.

  6. colinc says:

    Excellent! Now, Smithers, release the hounds!!

  7. AA says:

    This is ridiculous.

    The efficiency of renewables is nowhere near 100%, but since you don’t buy the “fuel,” it isn’t measured in the UK gov statistics.

    Typical PV can convert 15-20% of the energy hitting it into electricity (then you have inverter, and possibly storage losses).

    I can’t find the actual wind energy conversion rate for most big wind turbines, but I know it can’t exceed the Betz limit of about 60%. (it’s probably much lower than that. Seeing as the author works for EWEA, perhaps she could find the actual figures?)

    The “66% wasted” figures for fossil fuels imply that we could wring 3 times as much energy out the fuel in generating electricity, but in practical terms we really can’t. We could use some of that “waste” for process or space heat, i.e. cogeneration.

    Just as PV can’t turn 100% of sunlight into electricity, or wind turbines can’t turn 100% of the kinetic energy of moving air into electricity, thermal plants cannot turn 100% of the fuel energy into electricity.

  8. AA says:

    Well said.

  9. Joan Savage says:

    Good point. Downwind of a turbine, the lower wind speed and more turbulent air pattern is higher entropy, but it isn’t usually viewed like the ‘waste’ heat from other energy sources.

  10. Dick Veldkamp says:

    Why is the capacity factor for wind turbines 0.20-0.40)? As a wind turbien engineer, allow me to explain.

    The definition of the capacity factor is:

    e = (realised average power) / (rated power)

    How should we chooose rated (maximum) power? We can build a wind turbine that always produces the Betz-maximum of 59%. This turbine would be very heavy, because it must be strong enough to operate at force 12 (hurricane force). It is more economical to cut off the power a some lower wind speed. This is typically done at force 4-5 (ca 12-15 m/s). This is smart because there are not that many hours with higher wind speed than this. It simply does not pay to make a turbine that can also produce Betz-power at those speeds. On a yearly basis, there is simply not that much energy at those speeds.

    So what manufacturers do is choose rated power (i.e. generator size) to minimise kWh-price. Thus the capacity factor has not much meaning, and says exactly nothing about efficiency.

    PS On land e=0.20 or so, offshroe it may be as high as e=0.50.

  11. Mike Straub says:

    These sorts of arguments against Wind energy, or other renewables astound me. A little foiled air, or a carbon impact that could leave our great-great grandchildren walking around with gasmasks on? My other favorite argument is, “the turbines are too ugly!” … Ok, we’ll build a coal burning plant in your backyard instead.

    You’re either a fan of creating cleaner, affordable forms of energy that we can proudly hand off to future generations, or you prefer to make oil companies filthy rich while they just make our world plain old filthy.

    The innovations coming along every day give millions hope for a cleaner, more reliable, more affordable energy future. There are places across the globe that can’t afford oil prices right now, just imagine how hard they’ll have it in in 10 years! Thank goodness for innovations like Ocean Thermal Energy Conversion (OTEC), it creates an endless flow of power from the temperature difference in shallow and deep water, it’s been proven for decades, is zero emission, and can produce millions of gallons of clean drinking water by just diverting a little of the power from the plant. It’s a life changing technology for millions living in developing nations. These are the kinds of ideas that will improve lives, and cut us off of expensive, filthy, fossil fuels. And it’s just one idea, more come out on a daily basis, giving us all hope for the future.

    Lots more on how OTEC works at The On Project

  12. Antoni Jaume says:

    When using electrochemical processes on can get a much better returns than with thermal processes. So if we could use fuel cells with petroleum or coal, not easy for sure, the waste in electricity production would shrink to 15% or less.

  13. Jen says:

    Yeah the sun should be operating 24/7 around my place so I never need to turn the lights on at night. Oh, wait a mo, there wouldn’t be any nights!

  14. Kent Doering says:

    Nice one, Ms Casey. Wouldn´t it be great if you could write something about the massive coming build up of wind in the U.K, Ireland, Germany, Holland, France, Belgium, the Iberian Peninsula just to give Americans an inkling of how the Europeans are catching on to wind in a massive way.

    If I understand European Wind Association stats correctly, Germany alone is building out a total of 55.000 wind turbines, many with outputs of up to 5 MWh, average 3 MWh by 2020.

    I myself am distantly involved in the massive German project near Helgoland- the biggest offshore wind project to date… with a power output of up to 3.5 GWh, the equivalent of 4 sixties type nuclear reactors Germany shut down.

    It is a fascinating project. It is the furthest out Germany has ever built an offshore wind generation project- midway between its state of Schleswig Holstein and the Great Britain coastline. It is a “learning by trial and error” project as well.

    The four massive transformer stations have to be 20 meters (65 feet) above the average North Sea Surface so as not to be battered by even big waves. Each one is about the size of a football field. And they transform the power to HVDC which will be conducted by, low transmission loss, HVDC cables to onshore transformer stations. it is a learning experience for the participating companies because nothing this far out at sea has been done before. This is important because the learning process can be applied in optimising future big offshore wind projects.

    Americans are concerned about unemployment, so it is always important to note how onshore and offshore wind projects supported by some government subsidies and guaranteed feed in tariffs create jobs in manufacturing, shipbuilding, and maintenance, stressing that all fossil fuel costs are eliminated. There are other problems which must be met such as anti-corrosian coatings on the towers, the turbines, and even special alloys in the generators to cut corrosian due to the high salt content of the air. High sea offshore is an electrical engineering and maritime construction challenge.

    Many opponents of offshore wind, friends of nuclear or fossil fuel p.g., try to give the illusion that after amortization, new wind turbine towers have to be built to replace them. Perhaps the association could make it clear that repowering entails taking the generator off the tower, replacing it, and then refurbishing it for replacing another unit on another turbine, and that with proper maintenance and care, an offshore wind turbine can give centuries of service.

    The other key point is cutting fossil fuel consumption, costs, and emissions in power generation. Norway, for example, is generating so much power by hydroelectric and wind that that its own Stadtoil nat gas fired combined cycle power plants operate at a wait state, leaving them more gas to export to other countries. The plans by Cheneir energy to export U.S.Marcellus shale gas via L.N.G. to Europe and the massive build out of wind, let E.ON, a big German utility, renegotiate gas prices with Russia delivered on the Baltic Sea pipeline to lowered prices. That is, the bigger the build out of wind and solar, the lower the demand on gas, which keeps gas prices lower. (The U.S. has a glut of shale gas at the moment, but the expansion of wind would not displace gas, but rather coal.- and keep gas at lower prices at the same time.)

  15. Joe Romm says:

    We’ve written a great deal about the wind surge overseas.

  16. Solar Jim says:

    If defining technocratic energy efficiency by the equation of Energy Out divided by Energy In, then placing a lithosphere substance (aka fossil “fuel”) in the denominator gives a meaningless/unknowable result.

    Fossil “fuels” do not waste energy, they are not energy at all. Fuels-of-war are not “resources of energy,” but explosives. A civilization that does not understand the difference between matter and energy is a very temporary civilization, as we are beginning to discover.

    Have a nice debate. (Debate is what you catch the prey with. Associated with doubt.)

  17. Daniel Coffey says:

    Solar cannot win against wind for a variety of reasons. First, there is no real contest, as one might believe if you listen to dogmatic environmentalists. Wind and solar complement one another and produce electricity from entirely different extractable media.

    The notion that separates solar from wind has to do with temporal considerations and the energy density of the media extracted. Wind is stored momentum created from solar radiation on the atmosphere; solar panels convert light into electricity directly, when light exists and not otherwise.

    Most important, wind turbines extract energy from a vertical flow of air, not based on the area covered. Wind turbines can easily coexist with other land uses, such as wildlife, farming, water, etc, and thus have a number of practical advantages over solar panels.

    However, it is a huge mistake to pit wind against solar on the assumption that it is a zero-sum game. It is not, and the thing to be reduced as quickly as possible is releases of greenhouse gases.

  18. Daniel Coffey says:

    Comparisons based on efficiency are misleading because they do not relate to a common basis. The real basis is the extractable energy available in a media which technology can utilize in order to do work. As arcane as that might seem, it is what people should be focusing on: solar to wind via turbines, solar to electricity via PV, solar to heat via thermal panels, solar to plant material via photosynthesis, etc.

    Only when one focuses on the energy available in the extractable media does one get a real basis for efficiency, a number which is really meaningless in most contexts.

    By the way, solar to plant material via photosynthesis is about 1% efficient; 100 watts of sunlight produces 1 watt of stored potential energy. When that 1 watt is then extracted via a highly efficient thermal process, it produces 1/2 watt of electricity.

    A solar panel extracting the energy in photons and converting it to electricity produces between 10 and 40 watts from each 100 which falls on the panel, depending on the technology (thin film, Concentrating triple junction PV, Etc.).

    So, a good solar pV panel extracts useful electricity about 80 times as much energy as was laid down in a fossil fuel produced from photosynthesis. The difference, and this is critical, is that solar PV is not stored energy as is the case with hydrocarbons.

    Therein lies the really big difference – storage of energy.

  19. AA says:

    That 85% conversion rate includes reusing the waste heat, which is something we could do with thermal processes (co-generation, district heating, etc.).

    The efficiency of fuel cells without recycling waste heat is similar to what a good gas fired plant can achieve.

    The advantage of fuel cells is that it is easier to install them close to demand for space or process heat, so you’re more likely to achieve that co-generation benefit.

    Note that gasifying coal or oil will reduce your overall efficiency, so it’s probably best just to burn them as efficiently as possible (unless you’re going to be capturing and sequestering carbon, but that introduces even more complications).