# The Energy Return of The Three Gorges Dam

In preparing my previous post on Net Energy Trends I wanted to include a back of the envelope calculation on the ERoEI of hydro electric power using the Three Gorges Dam as an example. But I got my decimals pretty muddled leading to an answer that was implausible. But I’ve now had a few days off to clear my head and I put a new battery in my calculator and so hopefully the calculation is now on the money.

Looking at just the labour and embedded energy of the concrete and steel and assuming a 45% capacity factor and 70 year life yields a partial ERoEI of 147. And so, despite substantial environmental harm and social disruption I must give dispatchable hydro electric power a big thumbs up. See the calculation below the fold.

The Three Gorges Dam on the Yangtze River in China is the largest hydroelectric scheme in The World. Operational since 2008 it has 22.5 GW installed capacity. The Itaipu Dam on the Parana River between Paraguay and Brazil produces a similar amount of electricity from 14 GW capacity and achieves this through a higher capacity factor.

Recent posts on ERoEI indicated that hydroelectric power had ERoEI >> 50 and I just wanted to check these claims. But before proceeding lets get the metric prefixes sorted since we have to manipulate some fairly large numbers:

mega = 10^6 = million
giga = 10^9 = billion
tera = 10^12 = trillion
peta = 10^15 = one thousand trillion
exa = 10^18 = one million trillion

### Three Gorges Vital Statistics

Installed generating capacity = 22.5 GW [1]
Capacity factor = 45% (0.45) [1]
Concrete = 27.2 million m^3 [1]
Concrete = 65.2 million tonnes*
Steel = 463,000 tonnes [1]

*1 m^3 concrete = 2.4 tonnes
1 TWh = 3600 TJ [2]
1 toe = 42 GJ [2]

### The Energy Return

This is always the easier part of the ERoEI calculation but even here assumptions need to be made about capacity factor and lifespan. Wikipedia report 45% capacity factor which I presume is based on design criteria and performance to date. And I have assumed a 70 year lifespan. Lifespan could easily be much longer and this will simply add to the ERoEI.

0.45 * 22.5 GW * 24 hrs * 365.25 days * 70 years = 6213 TWh = 22.37 EJ

### The Energy Invested

I am not going to attempt a detailed and complete analysis here but will try and make ball park estimates of energy consumed by labour and the main materials – concrete and steel.

Labour

60,000 workers laboured on the project that began in 1994 [3] and was completed in 2003. Taking 1998 as the mid point China had a population of 1.242 billion and consumed 905 million tonnes oil equivalent (Mtoe) in energy that year [2]. This yields a per capita consumption of 0.75 toe. The sum for the energy cost of labour therefore is:

60,000 workers * 0.75 toe per annum * 10 years = 450,000 toe = 18.9 PJ

Materials

There is a range of numbers for the energy content of materials. I am going to use:

Concrete = 1.9 GJ / tonne [4]
Steel = 20 GJ / tonne [5]

65.2 million tonnes concrete * 1.9 GJ / tonne = 123.9 PJ
463,000 tonnes steel * 20 GJ / tonne = 9.3 PJ

Total Energy Invested

labour 18.9 PJ + concrete 123.9 PJ + steel 9.3 PJ = 152.1 PJ

### The partial ERoEI

Energy return = 22.37 EJ / energy invested 152.1 PJ = 147
Energy pay back time works out at an incredible 6 months.

(Energy produced in 1 year = 22.37 EJ / 70 = 319 PJ. Energy invested = 152.1 PJ. Hence energy pay back time = 152/319 = 0.48 years.)

I am quite satisfied with this answer. Some of the input numbers used may be wide of the mark and the energy inputs are far from complete. For example the diesel used on the construction site is not included along with many other energy inputs. But the answer is in the same ball park as calculated by other workers. Hydroelectric power is a tremendous source of dispatchable renewable energy. It does however come with high environmental and social costs. There’s no such thing as a free lunch in the energy world.

### References

[1] Wikipedia: Three Gorges Dam

[2] BP

[3] Facts and Details: THREE GORGES DAM PROJECT

[4] Australian Government: Embodied Energy

[5] Wikipedia: Embodied Energy

This entry was posted in Energy and tagged , , , . Bookmark the permalink.

### 26 Responses to The Energy Return of The Three Gorges Dam

1. Alex says:

One of the issue raised about hydro electric power is the release of methane from flooded areas, the effect of which apparently exceeds the embedded.

http://www.scientificamerican.com/article/methane-emissions-may-swell-from-behind-dams/

I don’t know how this would effect the EROI of dams, but it needs to be considered.

• burnsider says:

The methane (and CO2) arises from flooded vegetation and deep peat, but this is unlikely to amount to much in the Three Gorges reservoir due to the terrain.

I read years ago about a hydro scheme in Canada (?northern Quebec) which covered a huge area of blanket bog with relatively shallow water. Calculations indicated that in terms of emissions, it was barely better than fossil generation for the first few decades. Long term, it will be a winner like the Three Gorges

• Euan Mearns says:

Environmental harm does not impact ERoEI unless you expend energy trying to mitigate or repair it. As readers of this blog should already know I am in favour of a holistic approach to measuring environmental impact. Not the monolithic approach of considering only CO2 emissions.

But as a species we need to choose between having energy and accepting the inevitable environmental harm or not having energy and perishing. As a sub-species the OECD is in danger of submitting to the latter while the rest of the world gets on with the former.

2. Wm Watt says:

We can’t participate in such government projects as the Three Gorges Dam but there are opportunities to participate, ie put our money where our keyboards are, in private power developers. One example headquartered here in Canada is Brookfield Renewable Partners whose global electricity generation in 2015 was 5,249 GWh of hydro and 636 GWh of wind. It says 215 hydroelectric generating stations on 81 river systems in the USA, Canada, Columbia, Brazil, and Europe. Not meant as a plug for BEP, just a reminder that we can do more than sit on the sidelines as objective observers. Disclosure: I don’t own shares in BEP directly but do in BrookField Asset management which has a 63% “economic ownership” in BEP.

• RDG says:

Euan Mearns: “There’s no such thing as a free lunch in the energy world.”
Hordes: “There sure as hell is and hydro is it”

Example. The bankrupt state of Illinois is looking to outsource its electricity generation from “cheaper sources” in other states. Now consider probably most states in the so-called United States are in the same dire financial situation and no doubt have the same strategy. Surely, the laughable Department of (No) Energy is of any help with the piddly solar.

Tell me why this isn’t any different than Venezuela, only much larger scale. What are these private developers going to do: “Oh I’m sorry, but the state of Illinois is not paying its bills so we just had to cut them off and watch them all die off.”…Nah, the hordes will have their way! Gotta submit to the hordes, never forget that!

Now we have Jamie Dimon sounding the alarm on all the bad auto loans and that “somebody is going to get hurt”.

• David Whannel says:

Source The Paper World of Brookfield Asset Management and the WSJ report on their corruption and think twice about promoting them on a blog based in Scotland given their exclusive links to our government, and of course, divest.

3. Ajay Gupta says:

Thanks for the calcs again. Hydropower is probably the crown jewel of electricity generation by EROI standards (especially when environmental damage is not included), but the west is pretty much saturated with hydro (I think). Plenty of opportunities in east but then there’s that problem of caring about their environment (at some point any ways). I have no idea about prices in the east.

• Yvan Dutil says:

Yes, Ajay. Hydro has a tremendous EROI. However, the potential for new generation is low and decent rivers are very far now.

• Graeme No.3 says:

But in Africa and South America?

• OpenSourceEnergy says:

Grand Inga and a chain of Hydroper stations along the Kongo falling several hundred meters towars the sea with some of the highest water amounts on earth is still waiting for development.
Be aware that the three gorges dam received already additional turbines to be more capable to balace variations in renewable production.

• Leo Smith says:

There are some good places left. Nepal for example. and all the foothills of the Himalayas.. But politics…

If you have the climate and the terrain, its a great way to make your country wealthy. If not, there is always nuclear.

Worst place is middle of dry arid desert. No hydro, no cooling water..but fortunately no people either.

• Euan Mearns says:

http://euanmearns.com/energy-in-africa-electricity-s-of-sahara/

I seem to recall that some African countries with hydro exported the power. One problem with hydro is that you also need a grid. And so I am actually with those who support solar PV in Africa backed by battery storage. A little electricity in isolated villages may provide a lot of prosperity.

And the Himalayas are often a severe earthquake risk.

• Syndroma says:

There is a project to build 20 GW hydro plant in Eastern Siberia. 1,000 km away from the grid. No local consumers, no infrastructure. But the river is there.

• Leo Smith says:

If we were to build nuclear with as little concern – or as much concern – for the environment as we build hydro, it would be pretty competitive.

Hydro needs MORE concrete to do the dam, typically, so that’s a plus for nuclear.

Nuclear needs reactors and steam boilers in addition to te generating sets and te turbines, so that’s a minus for nuclear.

But overall there isn’t much in it….

…until we come to meeting regulatory hurdles. Hundreds of thousand of people and a few forests of paper and lord knows how many petabytes of storage are needed to comply with a raft of regulations.

Imagine: You are drilling into a bit of concrete to put up a pipe support, and you are off by an inch, and hit a reinforcing bar.

1/. You have made an unauthorised design change, which means that the whole project will have to be re-authorised.

2/. You have had a ‘nuclear accident’ ‘potentially impacting the integrity of the plant’ . That’s at least 6 months of inquiry and paper work right there.

3/. Work is suspended whilst all this goes on. Only another billion in interest charges..

4/. It is decided that for the safety of the plant, the whole bit of concrete that has been compromised, will be demolished and new bits laid, so there are no issues with the reinforcement.

AS a result 60,000 people have been kept idle and another 5000 have been kept busy doing nothing whatsoever towards building a power station. And they all consume energy.

That’s pretty much how the EPR is going at Olkiluoto and Flamanville…

https://en.wikipedia.org/wiki/EPR_%28nuclear_reactor%29

4. I’d like to know what the environmental costs are – huge, I imagine. Not sure if those costs can be justified.

However, aren’t their ongoing inputs? How many people work on operating and maintaining it, what goes into ongoing maintenance? Down the line, are there decommissioning costs?

I’m not saying the EROEI is ever going to be poor on hydro but maybe not quite as high as this rough calculation. Environmental costs are the difficult factor. How on earth does one cost that damage?

5. Willem Post says:

Euan,

The hydro energy is steady, dispatchable, not intermittent, not variable, unlike wind and solar, so their energy cannot be compared with these energy sources, unless apples to watermelons is OK.

22.37 EJ/y would be many thousands of wind turbines that would last at most 20 – 25 years.

22.37 EJ/y x 0.25/0.45 CF ratio = 12.43 EJ/y from 22.5 GW of wind turbines

At 3 MW each, 7500 units, spread out over 22,500 MW x 60 acres/MW = 1,350,000 acres.

At a capital cost of 22,500 MW x \$2.5 million/MW = \$56.25 billion, for the first 22.5 years, after that major refurbishments and replacements for the next 50 to 75 years.

The Danish government has greatly limited future wind turbine build-outs, because it became too expensive.

I and many others could have told them that at least 10 years ago, but they would not listen; too pre-occupied with RE rah, rah.

The German government similarly reduced wind turbine build-outs, to rein in runaway costs of its energiewende, with wind CFs at 0.20 and solar CFs at 0.10. Yikes, what a waste of capital and other resources.

With less RE rah, rah, sanity re-emerges.

That may also be due to the \$40 billion per year for 1 million recently arrived, culturally different “refugees”, which is creating a political backlash.

Germany, with a very-slow-growth economy, and after shunning, for geo-political reasons, a big, very profitable client, is also starting the feel the limits of its follies.

• Beamspot says:

Well, I found that Hydro is also quite seasonal, at least in Spain (dry summers), and I guess also in Norway (ice in winter), so it is not his ‘perfect’.

Anyway, it is by far the best renewable we have, and I strongly support it. But it seems that it is not this ‘green’ (impacts are really high, but in fact, ALL energies have some impact).

After all, it was the third renewable energy used by humankind, after biomass (many thousand years ago) and wind (more than two thousand years).

I wonder there are other kind of reasons why for many people only PV is ‘green’.

• jim brough says:

New Zealand had a recurrence of an existing problem when in 2008 lack of rainfall could not fill the dams to make the electricity it needed.
Will it build more dams?

Look at IEA statistics and discover that Australia’s dry continent produces much more hydroelectricity per capita than Germany because it built dams in good places because it understood a long time ago the problem of rainfall variability.
Now classed as “climate change”.

6. Euan Mearns says:

The hydro energy is steady, dispatchable, not intermittent, not variable, unlike wind and solar, so their energy cannot be compared with these energy sources, unless apples to watermelons is OK.

The broad boundary ERoEI analysis of Ferroni and Hopkirk actually accounted for the energy cost of intermittency although perhaps not in the most applicable way. But an effort can be made to make it apples and pears instead of apples and melons.

• Willem Post says:

Euan,
“But an effort can be made to make it apples and pears instead of apples and melons.”

The ERoEI part is low-cost, on paper but the physical aspect of making a pear into an apple is very expensive, as proven by Denmark, Ireland and Germany.

7. roberthargraves says:

I was just at the Three Gorges Dam last month. China emphasizes other benefits, as well. By increasing the depth of the water by 100 m above the dam, the river became navigable upstream. The land downstream is very flat, and the Yangtze river course would change dramatically during heavy floods, wiping out cities and towns. We drove on a highway right of way that was previously the river right of way! The flow is now more controlled.

Plenty of potential in South East Asia, however, as has been mentioned above, there are big political issues. I’ve just spent 12 days in Vietnam. Our guide mentioned that the Vietnamese were very concerned about the potential impact on their river systems, should their neighbours in Laos & Cambodia start damming rivers.
Vietnam has 75% of its electricity coming from hydro, the rest from coal.
We’re seeing pressures in the Middle East from countries damming rivers, thus reducing water flow to their down stream neighbours, even just for the filling periods for the reservoirs.

9. sod says:

At least the relocation should be factored into ERoIE.

“As of June 2008, China relocated 1.24 million residents (ending with Gaoyang in Hubei Province) as 13 cities, 140 towns and 1350 villages either flooded or were partially flooded by the reservoir ”

https://en.wikipedia.org/wiki/Three_Gorges_Dam#Relocation_of_residents

• Euan Mearns says:

Yes, the energy cost of collateral damage should be counted.