[paulinenehring]

Many countries are very rich in water resources, high yearly average precipitation, yet, none of this valuable renewable energy is used in electrical generation, why?

let me present some numbers:

a- Average yearly precipitation
b- Percentage of Electrical Generation produced from hydraulic sources

Paraguay : a- 1130 mm b- 100 %
Iceland: a- 1940 mm b- 73.81 %
Jamaica: a- 2051 mm b- 2 %
Cuba: a- 1335 mm b- 0.85 % on hydroelectric and
United Kingdom : a - 1220 mm b- 0.9 %

Source: http://lebanese-economy-forum.com/2012/paraguay-and-iceland-a-role-model-in-renewable-energy-usage-and-sustainability/

If Paraguay and Iceland have almost the same Precipitation as Jamainca, Cuba and UK, why isn't the situation the same in the United Kingdom, Cuba and Jamaica in terms of hydroelectric power generation.

Doesn't this surprise you? If a cheap, green and sustainable alternative to coal, oil and natural gas is available, why wouldn't governments of countries like (United Kingdom, Cuba and Jamaica) adopt it?

[vtsnowedin]

Welcome to the forum.
Hydo-electric projects need both rainfall and a drop in elevation between where the rain fails and the outfall of the hydo dams generating house. In short England is too flat and the land already developed so too expensive to flood behind dams high enough to be efficient.

[KingM]

Because Iceland has a tiny population and Paraguay's hydro comes from a dam on the Paraná River, which is the second largest river in South America. The water that powers the turbines comes from a huge Brazilian watershed.

England is too flat to develop much head and damming a large river like the Thames would mean displacing millions of people.

[sparky]

.
Some of the considerations also are geologic stability , this rule out Iceland and Japan
hydro dams are inherently dangerous to the communities down-stream
often there is international trouble if the water is needed elsewhere
turkey /Irak , India /Bangladesh , Sudan /Egypt , Laos / Vietnam have some disputes about water rights

Hydroelectric dams are very expensive to build , but cheap to operate
it take some years to compensate for the CO2 cost of all this concrete

they are usually used for several purpose , flood mitigation and water supply
sometimes those purposes are not compatible
they do interfere with wildlife and sites to some degree

There is no such thing as a free lunch or a free MegaWatt

[Quinny]

Maybe someone could invent a downspout turbine. It might generate enough to power a laptop.

[PrestonSturges]

There have been some microhydro projects to charge cell phones, because people were walking hours every week to charge their phones.

[kublikhan]

Hydropower is also vulnerable to drought. I had a friend from Sri Lanka. They get a large portion of their power from Hydro. He used to talk about the frequent power outages when the water level in the damns fell. You also probably heard about the recent huge power outage they had in India, the largest power blackout in history. While the power grid in India has long been inadequate and suffers from numerous problems, one of the causes of the huge blackout was lower levels of hydropower because of drought and late monsoon rains. Climate change is altering the world's rain patterns, and with it the potential for hydropower.

That era’s electric excitement culminated with a three day blackout. Then, as now, a sweltering summer drought left this hydropower dependent island choked of electricity.

In Sri Lanka no rain = no lights, and our current bouts of darkness reveal that our reliance on the rain gods has hardly reduced over the past 15 years.

The much vaunted Norochcholai pollution plant, and the glorified generator (it runs on diesel) at Kerwalapitiya have come up short. It’s now clear that what really kept us (relatively) power-cut free for a couple of years was reasonable rainfall but the droughts are back and our grid seems no better able to cope with the strain.

10 Things To Do During Power Cuts (Sri Lanka Or India)

What caused the vast power grid failure that roiled India this week? Precise causes remain unknown, but one emerging explanation points a finger at the nation's severe drought:
"Part of the reason may be that low rainfall totals have restricted the amount of power delivered by hydroelectric dams, which India relies on for much of its power needs. Another cause may be that drought-stricken farmers are using more power than expected to run water pumps to irrigate their crops."

That's a drought-related double whammy: Low rainfall crimps energy supply because of its effect on hydropower, and jacks up demand by forcing farmers to irrigate more.

"Experts who met in Delhi in May to discuss climate-induced "extreme events" in India suggest that likelier threats include more short and devastating downpours and storms, more frequent floods and droughts, longer consecutive dry days within monsoons, more rapid drying of the soil as the land heats, and a greater likelihood that plant and animal diseases might spread."

Did Drought Cause India's Power Outage?

The old way of predicting stream flow—by taking records of past flow and designing dams based on those amounts—is ”becoming more complicated because of climate change,”

In tropical and midlatitude rivers, water sources are already flowing less or drying up altogether. A 2009 study by the National Center for Atmospheric Research, in Boulder, Colo., found ”significant changes” in the stream flow of a third of the world’s large rivers from 1948 to 2004, with 6 percent less freshwater flowing into the Pacific and 3 percent less making it to the Indian Ocean. Drainage into the Arctic Ocean, however, rose by about 10 percent.

Shrinking rivers have already reduced or even shut down power generation in existing dams when their reservoirs dropped below critical levels. As a result, drought-stricken countries like Kenya, the Philippines, and Venezuela have suffered periodic blackouts and electricity rationing in recent years. Kenya is quickly developing geothermal and wind power to compensate for unreliable hydropower.

They found that while midlatitude areas will generally experience reductions in river flow and thus hydropower output, some areas, such as Northern Europe, East Africa, and Southeast Asia, will probably see a boost. As expected, the most at-risk areas are those that have a high dependence on hydropower but will face decreasing river runoff. In Southern Africa, for instance, drier conditions could mean a decline of 70 gigawatt-hours per year in hydropower capacity by 2050. Afghanistan, Tajikistan, Venezuela, and parts of Brazil are likely to be hit hard, too.

According to Byman Hamududu, a native of Zambia and one of the lead researchers on the Norwegian study, Norway and other far north countries, where river runoff is likely to increase, have the ability to adapt quickly—for example, by adding turbines to already existing dams to put the extra flow to good use.

But in some places, the case for building more hydropower capacity is strong. In Africa, only about 7 percent of the economic potential for new hydro projects has been developed, according to the International Hydropower Association (IHA). Getting Africa closer to the level of hydroelectric development in the United States or Europe—70 percent and 75 percent, respectively—would provide a vast resource for the continent, says IHA business director Michael Fink. Those levels might be ”the best trade-off between deployment using hydropower and preserving some rivers in a natural state,”

The Future of Hydropower

[kublikhan]

Also, much of the developed world has already largely maxed out their hydropower potential. For example, The United States and Europe. The reasons for this potential hydro power cap have already been explained by others in this thread(geography, best sites already taken, etc.) Since hydropower has not been enough to provide for all of their power needs, these countries have to rely on other power sources to make up the difference. There is still potential for hydropower development in the developing world. And despite all of it's issues, hydropower is still being developed. But like another poster said, there is no such thing as a free lunch. Hydropower has it's own set of issues.

It is estimated the word has a total of about 8k Twh/year of economically feasible hydro potential. We are already using or constructing new hydro power for 3k Twh/year. That means that we have already tapped out about 1/3rd of the total economical hydro power potential the world has. Most of the remaining potential is in developing countries, many of which are expanding their hydropower. But a country like the UK cannot raise it's hydro sourced power to 100% of it's needs.

The world’s total technical feasible hydro potential is estimated at 14,370 TWh/year, of which about 8,082 TWh/year is currently considered economically feasible for development. About 700 GW (or about 2,600 TWh/year) is already in operation, with a further 108 GW under construction. Most of the remaining potential is in Africa, Asia and Latin America:
Technically feasible Economically feasible
potential: potential:
Africa 1750 TWh/year 1000 TWh/year
Asia 6800 TWh/year 3600 TWh/year
North + Central America 1660 TWh/year 1000 TWh/year
South America 2665 TWh/year 1600 TWh/year

At present hydropower supplies about 20 per cent of the world's electricity.

A number of countries, such as China India, Iran and Turkey, are undertaking large-scale hydro development programmes, and there are projects under construction in about 80 countries. A number of countries see hydropower as the key to their future economic development: Examples are Sudan, Rwanda, Mali, Benin, Ghana, Liberia, Guinea, Myanmar, Bhutan, Cambodia, Armenia,
Kyrgyzstan, Cuba, Costa Rica, and Guyana.

Potential exists in about 150 countries, and about 70 per cent of the economically feasible potential remains to be developed. This is mostly in developing countries.

Hydropower and the World's Energy Future

[Keith_McClary]

Hydroelectric dams are very expensive to build , but cheap to operate
it take some years to compensate for the CO2 cost of all this concrete

they are usually used for several purpose , flood mitigation and water supply

The reservoirs also wipe out agricultural land and forests. There is CO2 from decaying trees and soil. On the Nile, seasonal floods no longer replenish the soil downstream. In the long term the reservoirs will eventually fill up with silt.

[Plantagenet]

Dams wipe out salmon runs.

Taking salmon out of an ecosystem has disasterous effects on the entire ecosystem, as bears and wolves and other mammals often rely on salmon for part of their sustanance, other fish depend on salmon eggs, and the nitrogen the salmon bring into fresh-water lakes is essential for the health of aquatic plants in lakes and rivers.

Let the rivers run free.

[PrestonSturges]

I saw a study that examined the phosphorus isotopes found in old growth trees (British Columbia?) because you would expect the soils to be pretty poor. It turns out that the trees really depend on bear poop, and specifically the salmon.

Small dams can be just as a damaging as big dams. Even though they may not generate much power they can do terrific damage.

[Laromi]

In Australia, reputedly the driest continent on earth, the Snowy (River) Hydro-electric scheme has managed to turn rivers into creeks, creeks into billabongs and swamps and swamps into lifeless salt-pans lake Alexandria was heading the way of the Caspian sea, farmers were driven off the land, marginal land became uninhabitable and virtually totally unproductive over hundreds and thousands of acres. I guess that is a pretty fast profile of a crashed 1950's dream of cheap and ready energy and pillaging natures reserves.

[SeaGypsy]

This year the Snowy flooded for the first time since the dams were built. The lakes in the lower Murray and Darling have come back to life after 3 wet years. Still a lot of damage will take much longer to repair if ever. The farmers are happy, looking at their best year ever for a range of crops at the smae time as the USA is having a serious drought.

[ralfy]

What Kublikhan wrote. Eventually, countries will have to use different sources of energy, with some used as a backup if others fail.

In relation to this topic, lack of water also affects other sources:

"Record Heat, Drought Pose Problems for U.S. Electric Power"

http://news.nationalgeographic.com/news ... ower-grid/

[Tanada]

Many countries are very rich in water resources, high yearly average precipitation, yet, none of this valuable renewable energy is used in electrical generation, why?

let me present some numbers:

a- Average yearly precipitation
b- Percentage of Electrical Generation produced from hydraulic sources

Paraguay : a- 1130 mm b- 100 %
Iceland: a- 1940 mm b- 73.81 %
Jamaica: a- 2051 mm b- 2 %
Cuba: a- 1335 mm b- 0.85 % on hydroelectric and
United Kingdom : a - 1220 mm b- 0.9 %

Source: http://lebanese-economy-forum.com/2012/paraguay-and-iceland-a-role-model-in-renewable-energy-usage-and-sustainability/

If Paraguay and Iceland have almost the same Precipitation as Jamainca, Cuba and UK, why isn't the situation the same in the United Kingdom, Cuba and Jamaica in terms of hydroelectric power generation.

Doesn't this surprise you? If a cheap, green and sustainable alternative to coal, oil and natural gas is available, why wouldn't governments of countries like (United Kingdom, Cuba and Jamaica) adopt it?

Projects like http://en.wikipedia.org/wiki/Rampart_Dam have been stopped by political action in the USA, if people chose leadership with different goals then politics will change. If they change in one direction the Rampart Canyon Dam will be built quickly, if they change in the other direction the Glenn Canyon and Hoover dams will be demolished.

[Pops]

Don't know if it's been mentioned in this depressing thread but irrigation from surface water eventually makes soil sterile due to concentrating of salts.

http://www.sci.sdsu.edu/salton/TheSalinityofRivers.html

[vtsnowedin]

Don't know if it's been mentioned in this depressing thread but irrigation from surface water eventually makes soil sterile due to concentrating of salts.

http://www.sci.sdsu.edu/salton/TheSalinityofRivers.html

There are ways to deal with that very real problem.
Periodic over flooding with drainage systems to carry away the salt laden water for one but that takes even more water to do and if your running short year on year you will be getting salty.

[sparky]

.
I'm not sure if it's a general case , but in parched Australia
over irrigating create a water connection with the salty underground aquifer
the salt can them rise to the surface and crystallize by evaporation
then it is very difficult to get rid of it .
the Israelis were amongst the first to solve the problem , they developed drip irrigation

[Serial_Worrier]

In general I don't like dams because it destroys the wildlife ecosystems. Nothing beats carbon-based fuels(oil, natural gas, coal) and nuclear for energy density and reliability. Everything else(wind, solar, hydro, geothermal) is just greens playing self righteous jerks.