Water Power

Development of SmallHydro PowerExamining the potential of small hydropowerplants. By Christine Lins and Maria Laguna,European Small Hydropower Association(ESHA).

Approximately 70% of the earth’ssurface is covered with water, aresource that has been exploited

for many centuries. The exploitation ofhydropower has been characterised bycontinuous technical development,making it the leading renewable energysource in the EU. Hydropower nowaccounts for about 84% of the electricitygeneration from renewable sources andfor 13% of total electricity production in theEU. This article is limited to smallhydropower plants, since largehydropower is technically mature andalready well exploited. Small hydropowerschemes generate electricity or mechan-ical power by converting the energyavailable in the flowing water of rivers,canals and streams. Small hydropowerhas a huge, as yet largely untappedpotential, which should enable it to makea significant contribution to future energyneeds, offering a very good alternative toconventional sources of electricity, notonly in Europe, but also in developingcountries.

Small hydropower (SHP) schemes aremainly “run of the river”, with little or noreservoir impoundement, using the flowof water within the river’s natural range.Little dams create little pond, which isvery favourable for ecosystems, fish andwater storage. They can be designedwith a small head, generally on smallrivers with gentle gradients, or with ahigh head, generally on small rivers withsteep gradients. Run-of-river projectscan use all the river flow or only afraction of it and have limited environ-mental impact. Therefore, SHP is notsimply a smaller version of a large hydro

plant. Specific equipment is necessaryto meet fundamental requirements withregard to simplicity, high energy output,maximum reliability, and easy mainte-nance by non-specialists.

There are different definitions of smalland large hydropower. The EU definitionclassifies as large hydropower schemesas those with over 10MWe of installedcapacity, and small hydropowerschemes as those up to 10MWe ofinstalled capacity. The definition of smallhydropower schemes also covers microschemes (those with installed capacityup to 1MWe). Micro hydropowerschemes are more suitable for ruraldispersed communities. In particular, thepower generated from micro

hydropower schemes can be used foragro-processing, local lighting, water-pumps, small businesses andindustries, farms, and household in ruralcommunities.

To develop both small and microhydropower schemes, the principaltechnical requirements are:

• Suitable rainfall catchments area.• Hydraulic head.• A means of transporting water from

the intake to the turbine, such as apipe or a millrace.

• A turbine house containing the powergeneration equipment and valve gear.

• A tailrace to return the water to itsnatural course.

THE ADVANTAGES OFSMALL HYDROPOWER

Small hydropower plants combine theadvantages of hydropower with those ofdecentralised power generation, without

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Figure 1: Small hydropower schemes are mainly run-of-river.

Water Power

the disadvantages of large-scale instal-lations. Small hydropower is:

• A sustainable resource. It meets theneeds of the present without compro-mising the ability of future generationsto meet their own needs.

• An efficient resource. It can satisfyenergy demand with no depletion ofthe resource and with little impact onthe environment.

• A secure resource. Small hydropoweris available within the borders of onecountry, and is not subject to disrup-tion by international political events.This guarantees its security of supply.

• A clean resource. It does not involve aprocess of combustion, thus avoidingpolluting and greenhouse gasemissions.

• A renewable resource. The fuel forhydropower is water, which is notconsumed in the electricity generationprocess.

Small hydropower has been techni-cally feasible for decades. Given afavourable site, it can be economicallyattractive, sometimes even offering theleast-cost method of generatingelectricity. High head sites tend to be inareas of low population density, andlong transmission distances to the maincentres of population can often nullifythe low cost advantages at thehydropower plant. Low head sites arestatistically much more common andtend to be found in or near concentra-tions of population where there is ademand for electricity. Small hydropowerhas the ability to generate electricityinstantly, to supply both base and peakload generation, has a long life, is easyto maintain and is highly reliable.

OPPORTUNITIES

Small hydropower has a key role toplay in the development of renewableenergy sources in Europe, and an evengreater role in the developing world. Inthe light of increasing electricitydemand, international agreements toreduce greenhouse gases limiting theuse of fossil energy, environmentproblems, and the fact that in mostEuropean countries, the sites for largehydropower plants are mostly exploited,there is an increasing interest in devel-oping SHP.

This trend has been enhanced by theEU Commission issuing the WhitePaper: “Energy for the Future: RenewableSources of Energy”, and the Directive2001/77/EC, “Promotion of ElectricityProduced from Renewable EnergySources”, giving clear signals toincrease the use of renewable energy inorder to reduce environmental impactsand create a sustainable energy system.

The White Paper calls for the use of 12%energy from renewables, and the Direc-tive sets up specific goals to reach 22%use of electricity from renewables in theEU by 2010. For SHP, this means thatthere is an ambitious target of reaching14GWe of installed capacity by 2010,and generating 55TWh annually.

The Directive gives Member States areason to look at SHP, because it is thebest proven of all renewable energytechnologies. Of special interest forEurope, from both the economic andenvironmental points of view, isexploiting the high potential forupgrading and refurbishing existingplants.

Despite the RES-E Directive seeking tosimplify the national administrativeprocedures in the process of setting andrunning a SHP plant, currently there arean increasing number of institutional andenvironmental barriers which operatorsface in gaining permission to implementnew small hydropower schemes and ingaining affordable connections to thegrid. This is mainly because of thepressure of environmental groups, whichoppose SHP for its negative localenvironmental impacts on the riverecosystem. This hinders progress inmany developed countries. Sometimesno distinction is made between theimpact of large hydro and the impacts ofsmall hydro schemes and sucharguments are, however, often related tospecific cases and cannot be appliedgenerally to SHP. However, newtechnology and improved methods ofoperating SHP are steadily reducing thelocal environmental impacts byintegrating environmental issues andlocal populations in the planning, designand management process.

Hence the small hydropower industryhas been affected by exaggerated criti-cisms of negative environmentalimpacts, since SHP also has importantenvironmental and social benefits: itreplaces fuel-based power production,and thus contributes to climate changemitigation by avoiding greenhouse gasemissions. It can boost the localeconomic development of isolatedpopulations by producing autonomousand reliable energy, it is suitable forcooperative or communal ownership,

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Small hydropower has akey role to play in thedevelopment of renew-able energy sources inEurope

Figure 2: Small hydropower has only limited environmental impact.

Water Power

and combined with irrigation systems, itis an appropriate solution in developingcountries. Finally, small hydropower alsoreduces the risk of river flooding and, insome cases, it can also increase biolog-ical diversity.

Because of all these reasons, theissue of public acceptance has thereforebecome a high priority for the smallhydropower industry, together with theanalysis of the advantages and disad-vantages that new regulatory supportingschemes could bring to the sector.Indeed, one of the measures introducedby the RES-E Directive is the develop-ment of National support schemes and,if necessary, a future EU-wideharmonised support scheme. Currently,these schemes vary from country tocountry and range from feed-in-tariffschemes with premium payments toRES, to tradable green certificatesschemes, and other types of investmentgrants.

CHALLENGES

Small hydropower’s main challengesrelate to both economics and ecology.Small hydropower can be successfullydeveloped as long as it produceselectricity at competitive prices andunder conditions that respect theenvironment.

In order to increase the profitability ofsmall hydropower, either the sale pricemust be increased, or production costshave to be reduced. The first is a politicaloption, and the second depends essen-tially on the technology. Reducingproduction costs implies firstly, reducingconstruction, operation and mainte-nance costs and secondly, improvinghydro and electromechanical perform-ances. It is therefore essential to havewell-structured and coordinatedResearch, Development and Demon-stration (RD&D) programmes in order todevelop new machines and constructiontechniques which are simple, reliableand efficient. At the same time, the costsof environmental protection activities areat present so high that they discouragethe building of new developments or therefurbishing of existing plants. RD&D isessential in this field in order to developefficient and economic equipment andconstruction methods. An example ofthis is the design of “fish friendly”turbines.

Small and medium sized enterprises,which constitute the majority of goodsand services suppliers in the field ofsmall hydro, do not have easy access toRD&D, essentially for financial reasons.The fact that a large number of plantoperators are not aware of the benefitsthey can achieve through the use ofefficient technology prevents equipmentsuppliers from profiting from any poten-tial investments.

Moreover, the fact that hydropowerproduction has existed for many yearshas created the impression that non-professionals can easily design sitesand equipment. The unhappy conse-quence of this is that organisations,which generally support RD&D, imaginethat everything has already been devel-oped in this field, and that small hydrotherefore does not need support. Worsestill, bad solutions to specific problemshave led to the construction of plantsthat were unreliable or did not respectnature protection rules, thus leading tomistrust or outright refusal of this type ofdevelopment. Nonetheless, the majorityof small hydropower plants built duringthe 20th century do not suffer from suchdefects.

RD&D ACTIVITIES IN SMALLHYDROPOWER

RD&D activities in the smallhydropower area have concentrated on:

Electromechanical, control andmonitoring equipment

Current RD&D includes: systemiseddesign of turbines, testing of newconstruction materials, submersibleturbo-generators, squirrel cage induc-tion generators, synchronousgenerators, variable speed operation,

programmable logic controllers, digitalcontrol and graphical user interface.These activities are carried out andfinanced by constructors and suppliersof equipment.

Civil engineering works andgeneral design

For large developments, RD&D isdone on an individual plant basis, Calcu-lations and tests are carried out inuniversity laboratories, where scalemodels of water intake systems, dams,etc are used. A number of companieshave made specific efforts in this field,for example, in the use of geotextiles orinflatable weirs, the improvement of“Tyrolean” self-cleaning water intakes,the development of screening systemsfor downstream migrating fish andintegrated designs. This type of RD&D ismore likely to be financed through publicfunds.

Environmental issues

The main environmental problem witha small hydropower plant is the diversionof water from the river, and the conse-quent ecosystem modifications. Atpresent, RD&D is aimed at reducing theinterruption of river flow. Electromechan-ical equipment-related RD&D, carriedout by big turbine manufacturers in alarge number of projects, has dealt withthese environmental problems through:

• The design of environmentally friendlyrunner blades, which avoid majorinjuries to fish which accidentally passthrough the turbine.

• New materials and components toeliminate the use of lubricants thatcause pollution in the case of leakage.

• Low noise gearboxes and generators.

RD&D addressing environmentalimpact has almost always been fundedby the EU or some other public body.There is a range of techniques that areable to mitigate environmental andsocial impacts and these should beconsidered.

Global environmental integration isessential if small hydro is to be betteraccepted by the local public. Researchon new standardised methods to testlocal individual sensibility to environ-mental problems, and new solutions to

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Small hydropoweralso reduces the riskof river flooding and,in some cases, it canalso increase biologicaldiversity

Water Power

achieve a higher participation by thepublic in the design process, should befavoured. It is the role of governments toput forward policies and regulations thatdo not unduly favour or penalise specificpower generation options, while effec-tively protecting the environment and therights of affected population. In settingup such policies and regulations, thepositive externalities of smallhydropower should be clearly recog-nised. The producers also have a centralrole to play. Environmental mitigationmeasures and compensation for peopleand communities affected by smallhydropower projects are well under-stood today and should be universallyapplied. Developers have a responsi-bility to fully integrate appropriatemeasures into project design. This alsomeans eliminating unacceptable alterna-tives early in the planning process andallowing for full community participation.

DEVELOPMENT POTENTIAL OF SHP

Small hydropower has a huge, as yetuntapped potential, which could allow itto make a significant contribution tofuture energy needs. There is still aconsiderable scope for improvementand optimisation. Proper maintenanceand refurbishment of existing plantscould considerably contribute to thedevelopment of small hydro. In Europe,despite a decrease from 86% to 60% of

total renewable energy capacityinstalled, small hydropower will remainby far the largest contributor.

Europe has the best state-of-the-artsmall hydropower technology to offer,but a domestic market which hasbecome more difficult despite nationaltargets for clean energy production.There are an increasing number of insti-tutional and environmental barriers to befaced in gaining permissions to imple-ment new small hydro schemes. Apartfrom this, the best home market for EUmanufacturers is the refurbishment ofexisting plants.

In the EU, the most active countries indeveloping new small hydropowercapacity are Germany, Spain andGreece. Small hydropower capacity isgrowing more rapidly in these countriesthan in other EU member countries.

Outside Europe, there are new oppor-tunities for export and technology

transfer that offer good prospects for EUmanufacturers. Economic growth and anincrease in energy demand will governhydropower development. Asia,especially China and India, is set tobecome a leader in hydropower, with83,000MW of further potential.

RECOMMENDATIONS FORSUSTAINABLE DEVELOPMENT OFHYDROPOWER

Some recommendations for a sustain-able development of hydropowerinclude:

• Energy policy framework. MemberStates should develop energy policiesthat clearly set out objectivesregarding the development of powergeneration options, including smallhydropower.

• Decision-making process. Govern-ments should establish an equitable,credible and effective environmentalassessment process that takes intoaccount both environmental andsocial concerns, with a predictableand reasonable schedule.

• Comparison of small hydropowerproject alternatives. Project designersshould apply environmental and socialcriteria when comparing project alter-natives, in order to eliminateunacceptable schemes early in theplanning process.

• Improving environmental manage-ment of plants. Project design andoperation should be optimised byensuring the proper management ofenvironmental and social issuesthrough the project cycle.

• Sharing benefits with local communi-ties. Local communities should benefitfrom a small hydropower project, bothin the short- and the long-term.

Small hydropower represents an alter-native to fossil fuel generation, anddoesn’t contribute to either greenhousegas emissions or other atmosphericpollutants. However, developing theremaining hydropower potential offersmany challenges, and pressures fromsome environmental action groups overits impact has tended to increase overtime. Moreover, in the context of therestructuring of the electricity sector,markets may favour more polluting andless costly options. ■

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Technical potential Economic potential Exploited potential Source: EU RES Export Masterplan 2002

TOTAL HYDROPOWER POTENTIAL BY CONTINENT

Graph 1: Total hydropower potential by Continent: Source ESHA (EuropeanSmall Hydropower Association)

Asia, especiallyChina and India, isset to become a leaderin hydropower, with83,000MW of furtherpotential