I fully agree with Miguel. In order to answer to this question with accuracy, a Life Cycle Analysis should be performed for the Renewable Energy Product or Technology. It is then possible to see how much "brown" is in the :green".

This is very good question. It will depend which part of the world the renewable technologies will be applied. Like for example, if the REs are available and no carbon-based energy sources, it is better to utilize such REs assuming that there is a financial resources to support the first cost or capital. Try to look the situation of Denmark for wind energy resources and you will appreciate the environmental and economic aspects of REs utilization.

Michel,

A very recent study addressing certain aspects of your question is to be found below. This document was coordinated by the task force "Future Fuels" of the German research organization FVV and addresses current and future fuel paths for internal combustion engines.

Renewable sources were investigated and benchmarked against fossil fuels.

The used well-to-wheel efficiencies are based on the European industry's gold standard, the JRC/EUCAR/CONCAWE study. The JRC is the joint research center of the European Union.

The piece is written in German but includes a very good executive summary in English.

Hopefully you will find the document helpful and interesting.

Best Regards

Ulrich

http://www.ufop.de/files/8913/8384/3541/20131107_FVV-Kraftstoffstudie_LBST.pdf

Of course it is green. But the point is that it is not being implemented in conservative way.

well, they are not completely green if you take into account some other parameters, for instance the production and material costs, but if we have made a depth analysis about the net energy cost and CO2 production (or avoid production) in the total life of this elements the green side will be the win!!!

Renewable energy sources by definition are green, but technologies used to transform them in to usable final energy not always are enwironmentaly friendly.

If thinking in terms of life cycle analysis (from cradle to grave) renewable energy tranforming technologies could be named as green, when in usage phase they have primary energy or CO2 emision payback in comparison to energy needs and polution made to produce that transforming system.

I agree with Karolis, the advantage is in the payback unless a point arrives when no more production of the systems is required then it would be totally green.

you can see some points in the following:

Kounetas, K., I. Mourtos and K.D. Tsekouras. (2012). "Is Energy Intensity Important for Produtivity Growth of EET Adopters?". Energy Economics , 34, 930-941

Tsekouras, K. and K. Kounetas. (2010). "Are the Energy Efficient Technologies Efficient?", Economic Modelling, 27, 274-283.

I hope it helps

I suppose you are talking about the emissions needed to produce the renewable energy components? (i.e. the steel/composite materials needed for wind turbines, for example). In this case, the problem is that it also depends on what your energy matrix looks like. If you have an energy mix made up mostly of fossil fuels, the initial carbon investment required for renewables is high (as most of the energy will come from coal plants etc). On the other hand, if you have a high component or renewables, a life-cycle analysis should give you a different answer...

I fully agree with Miguel. In order to answer to this question with accuracy, a Life Cycle Analysis should be performed for the Renewable Energy Product or Technology. It is then possible to see how much "brown" is in the :green".

The green quality of an alternative energy source is its pollution savings versus the current source, not the absolute pollution of the new source. Renewables are not always less polluting then mature fossil fuel systems of equal energy output. Every technology needs to be evaluated with a balanced approach covering energy vs pollution and cost.

It is green compared to the conventional sources of energy. Any technology will have some % 'brown' in it. We need to go for the less destructive. For example, wind--cutting down of trees, death of birds do to wind blades etc. But then which is better, coal or wind/solar

Thank you all for your valuable answers. I just want to clarify one thing. I was referring to the "cradle to grave" analysis. For sure renewable energy is greener than fossil fuel energy in the energy generation phase. But my concern is the energy needed to create the solar panels, wind turbines, etc. and the resources spent to transport them, is it also green? How much CO2 are we producing in the creation phase of renewable sources? And how about disposing of them?

It seems you are looking for the energy payback time, this is the time period in which a certain technology produces enough electrical energy to offset the energy needed for its production, maintenance, and disposal.

The energy payback time of modern large wind turbines is three to six months, the energy payback time of grid-connect PV systems is one to three years, depending on the local solar resource.

Just type "energy pay-back time of in google-scholar and you will find plenty of relevant literature.

A nice overview for PV:

http://cleantechnica.com/2013/12/26/solar-energy-payback-time-charts/

Primary energies are neither green nor polluting. The problem is that except for direct sunlight that can be used as source of heat by passive solar installations, no primary energy can be directly used as useful energy and has to be transformed. Transformation of energy is done by energy technologies. Energy technologies transform primary energies into intermediary energies and final energies (like an oil refinery or uranium enrichment), then demand devices transform final energies into useful demand (such as light, heat or mechanic work needed for transportation).

Technologies can be green or polluting. One of the possible criteria can be the sum of emissions either during the operation lifespan or across the entire life cycle (LCA from cradle to grave, as already suggested by Miguel Esteban and Gabriel Negreanu). Emissions are not all that dangerous and they have to be weighted for their greenhouse contribution.

But there are can be other criteria that add precision to the fuzzy term "green". One possible criterion, for example, could be an index called "energy returned on energy invested" (EROEI or ERoEI). Again, it can be computed only for the operation period, but a full LCA cradle to grave is better. For hydro power, ERoEI can reach 100. Coal mining and burning, the most CO2-polluting activity, can have ERoEI around 50 to 70. Nuclear with zero emissions can have ERoEI 10 to 50 but biofuels, so often praised as green, are around 1, just above or just below. Energetically, biofuels are a disaster and the same is for their economic parameters. They are profitable only thanks to State subventions that hide economic truth. Energy payback is a variant of ERoEI in form of a financial analogy.

Thank you Jethro Betcke for the information on Energy Payback Time.

And thank you Roman Kanala for the valuable information on EROEI.

I want to add a question to the conversation:

If we use renewable energy to produce/manufacture renewable energy (PV, Wind turbines, etc.), wouldn't the model be "greener"? Do renewable energy producers apply this philosophy? Is it the same in developed and developing countries?

The problem with renewable energy in general is with

1. their low energy density and

2. often their stochastic character.

In manufacturing, one faces with enough elements of incertitude that stem from the manufacturing process itself (machine failure rate, workforce absence, social movements, supply shortage, drop of demand, etc.) so that energy shortage is not acceptable. Hence the role of reliable and abundant baseload power - hydro dam, coal combustion or nuclear power plant.

Your questions are valid, but the answers will differ depending on the specific technologies, application and region. There is no universal answer.

What is true through, is that the hype of Green Technologies is often misplaced and misused by marketers.

A clear-cut case where Green Technology wins, is Battery Electric vehicles in France:

1. Over a life of 7y or 200 000km, a typical petrol/diesel car will emit 22 000kg of CO2.

2. In comparison, a battery EV, charged off the French grid (42g of CO2 per kWh) will typically emit 800kg of C02 for its 7y or 200 000km lifespan.

3. The same vehicle in South Africa, where we have 1015g of CO2 per kWh for electricity generation (not many renewables or nuclear), the same EV emits 20 300kg of CO2 over its life.

4. However, if the EV in South Africa is only charged at night, when there is surplus electricity and the coal is being burnt anyway, the attributable CO2 emission is much lower.

5. When comparing the CO2 emissions of 1) and 2), where the green technology emits 21 000kg less CO2 than the conventional technology, it is clear that even significant additional manufacturing and disposal emissions could not displace this advantage.

6. In other regions, then disadvantages may outweigh the benefits.

The EROEI is of course the project lifetime divided by the energy payback time. EROEI and energy payback time are useful to show that renewable energy technologies really produce more energy than they consume, and to compare renewables among each other. However, these concepts are not useful to compare renewable technologies with fossil fuel technologies because the emissions from the actual burning of the fossil fuel are not expressed in these indexes. To make such a comparison it is better to look at the emissions per kWh produced. For example look at:

http://electrical-engineering-portal.com/renewables-and-the-impact-on-environment

Thank you Gerhard Swart, Jethro Betcke, and all for you valuable answers. I think that I will start a research about the Economic evaluation of different technologies in electricity production including a complete analysis (from cradle to grave).

Hi there,

It depends what metric you want to measure 'greeness'. NREL recently made a meta-analysis of the GHG intensity of electricity production from various technologies:

http://www.nrel.gov/analysis/sustain_lcah.html

I have done a similar analysis for energetic 'cost' of wind, PV and CSP:

http://www.mdpi.com/2076-3417/3/2/325

I'm currently trying to get funding to do coal, gas, nuclear and hydro.

Otherwise, there are plenty of LCA review articles on the different technologies.

Mik

... additionally, you can find economic meta-analysis data here:

http://en.openei.org/apps/TCDB/

Thank you Michael for the valuable information

Renewable energy technologies are not really green & clean from (A) to (Z). At present, transition from fossil fuels is suggested to proceed towards either more clean synthetic fuels such as methane and/or methanol "derived from coal the last fossil fuel to be depleted" or into using renewable energy sources including solar, wind, geothermal, hydropower, biofuels, and waste-to-energy technologies. The current state of knowledge in these alternatives is not (as we wish) and each one of them has its own negative side effect(s). I am not aware of any research into "fully green" technologies, and what really goes on is the logic of "something is better than nothing" with many concerned persons hoping for close to greenish achievement. The significant problem, here, is the lack of true serious political decision by the most influential countries to go green & to stop the ongoing harm to the environment.   

Sometimes RET result in productive inefficiency and therefore a kind of an associated to o RET  "rebound effect" push down their green-es and clean-es. For a more comprehensive view on the above argument see my paper:

Kounetas, K and K. Tsekouras. (2010). "Are the Energy Efficiency Technologies efficient?" Economic Modelling, Volume 27, Issue 1, January 2010, Pages 274-283

I hope it helps

Thank you Nizar for your opinion, this is similar to my point of view.

Thank you Kostas for the reference.

emissions per kWh looks good, but maybe environmental impacts per kWh looks even better, taking into account impacts on ecosystems, species and habitats. A further question is additionality, which was prominent in CDM and carbon sequestration discussions. Impacts are also depending on sites (because ecosystem attributes may be destroyed, such as peatland for wind turbines and thus carbon is released) and on the choice of materials used for the technology (timber often has a much better carbon balance than concrete, steel or aluminum and even plastics).

emissions per kWh looks good, but maybe environmental impacts per kWh looks even better, taking into account impacts on ecosystems, species and habitats. A further question is additionality, which was prominent in CDM and carbon sequestration discussions. Impacts are also depending on sites (because ecosystem attributes may be destroyed, such as peatland for wind turbines and thus carbon is released) and on the choice of materials used for the technology (timber often has a much better carbon balance than concrete, steel or aluminum and even plastics).

Not really !  As to me green means environmental friendly. "Environment" includes every thing in the surrounding nature including people. 

You can imagine how much of natural fertilizer the soil lose when you use biomass for energy production.

Take the case of hydro power development, you need to displace people if they are living on the design map. 

How about the noise pollution by wind turbine on the nearby dwellers?

If renewable energy uses renewable resources, releases no  harmful byproduct to the environment and doesn't compete the environment for resources, then we can it  GREEN ENERGY !

Thank you Samuel Tesema Lakew for your point of view

I think exergertic  sustainability analysis which is based on the second law of thermodynamic can equally be used to determine the interaction of the system with the environment. It provides different indicators which defines different levels of degradation of any system to the environment.  

http://www.renewableenergyworld.com/green-power/tech.html

https://deepgreenresistance.org/hi/who-we-are/faqs/green-technology-renewable-energy

https://www.forbes.com/forbes/welcome/?toURL=https://www.forbes.com/sites/realspin/2014/09/24/is-renewable-energy-really-green/&refURL=https://www.google.com.tr/&referrer=https://www.google.com.tr/

Hydro power energy is considered as green energy. Recently i have conducted a research regarding the total GHG emission from hydro power. In this study i have found less GHG emission than diesel/oil consumption.

Around 782MW installed energy of hydro power produced 1.98% CO2 emission while 98.2% from fossil fuel combustion (Oil/Diesel) .

Thus, Hydro power is considered as a green energy.

This is a great topic indeed. Assessing and measuring externalities caused by fossil fuels or even by different types of renewable energies is essential also for international trade and WTO law. A country can legally discriminate foreign products that might affect the environment and health in favor of more environmental-friendly products, but science-based data on externalities are essential to demonstrate the these products are not like and to justify differential treatment and measures without violating the international trade rules. If anyone wants to work on this topic, just let me know by private message and we can communicate and exchange.

Furthermore, I would like to share with you the following paper: World Trade Organization, Renewable Energy Subsidies and the Case of Feed-in Tariffs: Time for Reform Toward Sustainable Development?”, 27 THE GEORGETOWN INTERNATIONAL ENVIRONMENTAL LAW REVIEW 4, December 2015, pp. 515 - 537.

http://papers.ssrn.com/sol3/papers.cfm?abstract_id=2704398

Looking forward to hearing from you.

Paolo

Traditional sources: coal, oil, natural gas.

How Coal is clean energy. It produces CO2.

After thoroughly cleaning the combustion products.

ok

Hello Michel,

I agree with the answer of Ulrich.

SIncerely

I guess that the correct answer to this question should consider two issues:

(1) The life cycle analysis (LCA) of costs, and emissions, and

(2) Comparison with other alternative energy sources.

In addition, the phrase 'green' may be replaced by greener where the term a green source may be defined as a source with minor pollutant emissions, and environmental hazards throughout its lifetime. Based on these issues, my answer is yes, provided that electrochemical energy storage is excluded. Based previous studies, the LCA of renewable sources, and their Energy Return on Energy Invested (ERoEI) places them in a greener position with respect to conventional energy sources excluding the nuclear sources.

I think the perfect answer to this question is Yes but with some conditions.

Two main things need to be achieved to make this dream come true,

1. Technological innovation to make energy conversion efficient

2. Business model innovation to avoid return on investment (ROI )calculation at end user ened i.e. ROI burdan must be taken care by policy makers

Sure, most of RE are really green, not like the polluted Fossil Fuels.

The CO2-equivalent emission during the production, 60 years service life and the decommissioning of different types of power plants is

Fuel value (in g/kWh)

coal 1023

oil 780

nat. gas 606

biomass 86

PV 71

geotherm. 67

wind 31

water 25

nuclear 14

Dear Michel, of course RE can compete with fossil fuel, especially in some remote locations, islands when people use diesel for the generators, and it is very expensive to bring the diesel by boats, or people just do not have electricity and living level is quite low.

If talk about non-remote locations and when necessary to produce a lot of electricity for many people, RE can not compete for now. Fossil fuel power plants (coal, oil, gas) is cheap and reliable, till country will have enough sources...

Costs on RE are dropping down (http://resourceirena.irena.org/gateway/dashboard/?topic=3&subTopic=32) and technologies are developing very fast, so I believe soon it can replace "old" style power plant, IF politicians and national oil/gas/coal companies will let do it, in many cases it is not only about technology itself, it is about the business of some group of people.

Regarding nuclear power plants.... It is very efficient technology, but a problem with it is the nuclear waste, I know in Russia, people just bury it in Siberia (I attached my report about it from uni with some numbers) and it is not a good solution....

@Polina Vasilenko

The paper attached to the answer (The-Economic-Report_07-02-2017.pdf) should not read without caution. 

The Pu-239 is a fissionable material, therefore it can be used as fuel, not for waste. The practical application is the MOX fuel, which is the fuel of the Russian BN-800 liquid metal cooled fast breeder reactors. Further information:

P. I. Lavrenyuk, A. B. Dolgov: The development and improvement of the nuclear fuel for power plants’ cores. Ninth International Scientific and Technical Conference «Safety, Efficiency, and Economics of Nuclear Power Industry» Moscow, 21-23 may 2014

http://mntk.rosenergoatom.ru/mediafiles/u/files/2014/Plenar_eng/6_Dolgov_TVEL_Development_and_improvement_of_the_nuclear_fuel_for_power_

plants’_cores_.pdf

Two years earlier the Hungarian experts dealing the investment of the new 2x1200 MW nuclear power plant at Paks (for replacement of the 4x440 MW old one) was informed by the Russian partner that all types of new Russian NPPs, except VVER-1200, are able to fuel with MOX (Oct. 26, 2012).

http://www.mvmpaks2.hu/hu/Dokumentumtarolo/EKD-HUN.pdf

The isotope composition of the spent fuel can be found in a lot of documentation available at IAEA. The two and a half million years half-life of U-234 is equivalent with a very small decay constant. The total activity is the mass multiplied with this small number. Why is selected U-234 as reference waste? (Btw, U-233 is fissionable, the reaction U-233(n,gamma)U-234 has low probability.)

The III+ and IV generations of NPPs are working with better "waste production" than the ones of II and III generations. The new Russian NPPs belong to the category III+.

The paper could be improved if it would be shown to a nuclear engineer. 

Hi Michael... there are many resources out there that will show you emmissions / kwh of each current tech. These assessments vary but generalky demonstrate similar outcome and generally are cradle to grave assessments (including manufacturing and disposal).

However - and one of the above contributers made the point. Emissions are not everything. There is also to consider impact in ecosystems through the replacement process of one tech (say coal) with another (say wind). This muddies the waters quite a bit. Consider a single Gassified (so emissions neutral) coal plant in one location at 1400MW vs 3 or 4 large scale wind farms of thousands of hectares each. We recently were involved in a 500MW windfarm and it’s footprint is 23 km x 12 km!

Also its worth recognising that cradle-grave assessments are done on design life and what I am seeing specifically in wind farms is that whilst their design life is 25 years - they are typically repowered (complete replacement with newer larger turbines, generators and masts) in as little as 10-15years. This actually has the effect of making their emissions assessments significantly inaccurate and shows them as a lot greener than they actually are