Removal of the 13 MW Glines Canyon Dam on the Elwha River (Washington state, US)Joel Rogers
<p>More likely, it is the cumulative impacts of small hydropower that should draw the concern of decision makers and energy planners, as illustrated by the proliferation of small hydropower dams in Switzerland. Though each of these dams may have a much smaller impact than the examples from the Penobscot and Elwha, what about hundreds of them, particularly when scaled to their energy contribution?</p>
<p>Three recent studies—from <a href="https://www.sciencedirect.com/science/article/pii/S1876610212007497" target="_blank" data-ga-track="ExternalLink:https://www.sciencedirect.com/science/article/pii/S1876610212007497" rel="nofollow">Norway</a>, Spain, and <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/wrcr.20243" target="_blank" data-ga-track="ExternalLink:https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/wrcr.20243" rel="nofollow">China</a>—have all concluded that small hydropower projects have larger impact per megawatt than do large projects. For example, in the <a href="http://www.mdpi.com/2071-1050/9/10/1807" target="_blank" data-ga-track="ExternalLink:http://www.mdpi.com/2071-1050/9/10/1807" rel="nofollow">Duero River Basin in Spain, small hydropower </a>projects (defined as less than 10 MW) caused nearly one-third of the total hydropower impacts in the basin, such as length of degraded channel and area of flooded land, but produced only 7% of the total generation. Further, with 140 small projects compared to 17 large, small hydropower created more than seven times as many barriers (e.g., for fish movement) compared to large hydropower. Meanwhile, the energy generated by small hydropower was 15% more expensive and was less flexible in terms of meeting grid demands.</p>
<p>Similarly, a <a href="https://www.sciencedirect.com/science/article/pii/S0309170805000370" target="_blank" data-ga-track="ExternalLink:https://www.sciencedirect.com/science/article/pii/S0309170805000370" rel="nofollow">study on the Willamette</a> River basin in Oregon found that a set of small hydropower dams contributed less than 2% of the basin’s total generation but caused nearly half the total loss of channel length available to salmon.</p>
<p>Thus, the presumption that small hydropower is low impact does not stand up to scrutiny.</p>
<p>But, globally, policies for small hydropower reflect the presumption, not the reality.</p>
<p>We now turn to the second and third issues and examine the policies that incentivize small hydropower and then consider whether those policies spur substantial contributions to clean energy and climate objectives.</p>
<p>In the US, several states with <a href="https://www.hydroreform.org/sites/default/files/2014-07%20hrc_state_rps_3.pdf" target="_blank" data-ga-track="ExternalLink:https://www.hydroreform.org/sites/default/files/2014-07%20hrc_state_rps_3.pdf" rel="nofollow">Renewable Portfolio Standards</a> (which mandate a higher proportion of renewables in the state’s electricity generation mix) don’t include electricity from large hydropower dams but embrace power produced from small projects (defined inconsistently as a megawatt capacity less than 30, 50, or even 100).</p>
<p>The <a href="https://cdm.unfccc.int/" target="_blank" data-ga-track="ExternalLink:https://cdm.unfccc.int/" rel="nofollow">Clean Development Mechanism</a>, launched under the Kyoto Protocol and intended to reduce greenhouse gas emissions, promotes small hydropower and streamlines its review due to perceived lower environmental impacts.</p>
<p>Countries across the globe—from China to Brazil to the Balkan countries of southeast Europe—have passed policies promoting small hydropower and subject its development to <a href="https://news.mongabay.com/2018/03/small-hydropower-a-big-global-issue-overlooked-by-science-and-policy/" target="_blank" data-ga-track="ExternalLink:https://news.mongabay.com/2018/03/small-hydropower-a-big-global-issue-overlooked-by-science-and-policy/" rel="nofollow">far less planning and regulatory oversight</a> compared to large projects.</p>
<p>Thus, climate and energy policies are promoting investment in small hydropower. But how much will the subsequent investment contribute to climate and energy objectives? The case of India is instructive. India’s renewable energy objective does not count large hydropower toward its total goal, but it does include small hydropower, defined as projects less than 25 MW of capacity. The policy seems to anticipate what the experience in Switzerland already demonstrated: the total contribution from small hydropower will be, well, small.</p>
<p>India plans for 5 GW of small hydropower out of a <a href="http://www.wri.org/blog/2017/05/achieving-indias-ambitious-renewable-energy-goals-progress-report" target="_blank" data-ga-track="ExternalLink:http://www.wri.org/blog/2017/05/achieving-indias-ambitious-renewable-energy-goals-progress-report" rel="nofollow">total renewable goal of 175 GW</a>. Even if each project built was the maximum 25 MW, that would require 200 new dams to provide just 3% of the renewable goal; because the proliferation of dams following incentives will likely include many that are much smaller than 25 MW, India could see thousands of new dams for what will amount to a rounding error in its national energy supply, even as studies show that <a href="https://timesofindia.indiatimes.com/city/nagpur/small-hydropower-units-making-big-impact-on-western-ghats/articleshow/64421447.cms" target="_blank" data-ga-track="ExternalLink:https://timesofindia.indiatimes.com/city/nagpur/small-hydropower-units-making-big-impact-on-western-ghats/articleshow/64421447.cms" rel="nofollow">small hydropower dams are having larger than expected environmental impacts</a>.</p>
<p>Taken together, these results and trends suggest that much greater caution and consideration is needed to guide planning and policy for small hydropower.</p>
<p>Though small hydropower may be appropriate for some situations—and there is considerable potential for innovation for small hydropower added within existing infrastructure—policies that promote the proliferation of small hydropower with limited oversight will likely produce significant cumulative impacts for insignificant increments of additional generation, while potentially diverting resources away from more effective solutions. Failure to improve policies that govern small hydropower risks the loss of tens of thousands of kilometers of healthy streams and rivers with very little electricity to show for it.</p>”>
A small hydropower dam in Zambia with a capability of one MWUNIDO
In 2008, Switzerland presented a feed-in tariff to advertise the growth of renewable power assets. Whilst the legislation incentivized assets akin to wind and sun, the builders of small hydropower tasks have been the most important beneficiaries: following passage of the feed-in tariff, 116 small hydropower dams were built throughout streams all over the place Switzerland.
Despite the fact that those small dams don’t flood entire valleys the best way massive hydropower dams incessantly do, they nonetheless fragment streams, save you fish from shifting upstream and, by way of diverting many of the water out of the channel and in opposition to a powerhouse, depart lengthy stretches of movement with dramatically diminished waft all the way through a lot of the yr. Generally, additionally they degrade the cultured great thing about a free-flowing movement in a bucolic valley.
And what did Switzerland achieve for dotting its stunning panorama with greater than 100 small dams and fragmented streams? The brand new small hydropower tasks generate 498 gigawatt hours (GWh) in line with yr, not up to 1% of the rustic’s annual era. Compared, a undertaking to rebuild an present massive hydropower dam at the Rhine with a brand new design added greater than 400 GWh, just about an identical to the era produced by way of the 116 new dams.
And it is not simply Switzerland – a contemporary find out about discovered that there are no less than 83,000 small hydropower dams all over the world (greater than 10 occasions the choice of massive hydropower dams), with tens of 1000’s extra within the making plans pipeline.
However the Swiss instance does successfully illustrate 3 main problems in the case of small hydropower. First, small hydropower is normally assumed to be a low—and even no—affect supply of low-carbon electrical energy. However, as mentioned underneath, this assumption is incessantly now not true.
2nd, due partly to the presumption of low affect, small hydropower is incessantly incentivized in insurance policies to advertise renewables below local weather alternate goals.
In the end, those incentives can cause funding that results in a proliferation of small dams that jointly make a mere contribution to the nationwide grid, at the same time as they’ll motive really extensive cumulative environmental affects.
Those problems underscore that call makers and effort planners must assessment small hydropower on its precise affects and sensible contributions to power and construction beneficial properties, now not on overly simplistic (and incessantly erroneous) assumptions. Generally, subsidies or incentives for small hydropower dams can be higher directed at different renewable choices, starting from new sun to modernizing present hydropower vegetation and including generators to non-powered dams (e.g., irrigation dams).
This isn’t to mention that small hydropower isn’t an acceptable answer. Actually, small hydropower (and even micro-hydropower) can give electrical energy to far off communities or give a contribution to decentralized mini-grids serving spaces out of doors number one grids. And firms are discovering leading edge techniques to deploy small hydropower which can be actually low or no affect, akin to including generators to irrigation dams or canals.
However those examples stay a small portion of funding in small hydropower; nearly all of small hydropower must obtain a lot larger scrutiny according to the 3 problems highlighted above.
A nine.nine MW hydropower undertaking in Albania that de-waters a stretch of the Rapuni River downstream (from Google Earth).
First, does small hydropower equate to low affect hydropower?
One problem to answering this query is that the definition of small hydropower varies dramatically. Within the Eu Union, small hydropower refers to energy vegetation with a capability not up to 20 megawatts (MW), however in person international locations the brink will also be decrease, akin to Sweden the place it’s 1.five MW. In India the brink for small hydropower is 25 MW, but it surely’s 30 MW for Brazil and 50 MW for China and Canada. In the USA, more than a few states outline it as any place between 2 and 50 MW.
So, for the reason that the definition of small hydropower is very variable, what do we all know concerning the affects of hydropower tasks that fall in that vary—each as person dams and during the cumulative affects of more than one dams?
When it comes to person affects, the most important thought is that the “small” in “small hydropower” virtually all the time refers back to the capability of the generators, now not the scale of the dam. As an instance what this implies in follow, believe two hydropower dams at the Elwha River in Washington – the Elwha Dam (15 MW) and the Glines Canyon Dam (13 MW). Those would have certified as small hydropower in line with maximum definitions but, to any observer, there used to be not anything small about them. Status 108 toes (33 m) and 210 toes (64 m), respectively, they have been really extensive buildings that totally crammed the canyon of the Elwha (see picture underneath). Their affects weren’t small both, as in combination they led to a 99 % aid within the Elwha’s salmon numbers, up to now upwards of 400,000 in line with yr throughout 5 species of salmon. The U.S. has now invested $350 million to take away the dams and repair the salmon.
In a similar way, 3 dams at the Penobscot River in Maine were got rid of to revive migratory fish populations, costing roughly $50 million. Absolutely blocking off an important river in New England for fish akin to Atlantic salmon and shad, the one factor small about those dams used to be their era capability, averaging 6 MW in line with dam. Very similar to the Elwha, those dams would have certified as “small hydropower” by way of just about all definitions, but each and every one had really extensive environmental and social affects.
The Penobscot and Elwha dams have been relatively outdated and these days it’s not likely that such massive and harmful dams can be constructed for such small beneficial properties in electrical energy. However taking into consideration that some international locations would outline a 50 MW dam as “small hydropower”, it’s value noting that even person small hydropower dams, if constructed within the flawed position, can have affects on fisheries or different values that might impact entire areas.
Removing of the 13 MW Glines Canyon Dam at the Elwha River (Washington state, US)Joel Rogers
Much more likely, it’s the cumulative affects of small hydropower that are meant to draw the worry of choice makers and effort planners, as illustrated by way of the proliferation of small hydropower dams in Switzerland. Even though each and every of those dams could have a way smaller affect than the examples from the Penobscot and Elwha, what about masses of them, specifically when scaled to their power contribution?
3 contemporary research—from Norway, Spain, and China—have all concluded that small hydropower tasks have higher affect in line with megawatt than do massive tasks. For instance, within the Duero River Basin in Spain, small hydropower tasks (outlined as not up to 10 MW) led to just about one-third of the whole hydropower affects within the basin, akin to period of degraded channel and space of flooded land, however produced most effective 7% of the whole era. Additional, with 140 small tasks in comparison to 17 massive, small hydropower created greater than seven occasions as many limitations (e.g., for fish motion) in comparison to massive hydropower. In the meantime, the power generated by way of small hydropower used to be 15% costlier and used to be much less versatile when it comes to assembly grid calls for.
In a similar way, a find out about at the Willamette River basin in Oregon discovered set of small hydropower dams contributed not up to 2% of the basin’s overall era however led to just about part the whole lack of channel period to be had to salmon.
Thus, the presumption that small hydropower is low affect does now not get up to scrutiny.
However, globally, insurance policies for small hydropower replicate the presumption, now not the truth.
We now flip to the second one and 0.33 problems and read about the insurance policies that incentivize small hydropower after which believe whether or not the ones insurance policies spur really extensive contributions to scrub power and local weather goals.
In the United States, a number of states with Renewable Portfolio Requirements (which mandate a better percentage of renewables within the state’s electrical energy era combine) do not come with electrical energy from massive hydropower dams however embody energy made from small tasks (outlined erratically as a megawatt capability not up to 30, 50, and even 100).
The Blank Construction Mechanism, introduced below the Kyoto Protocol and supposed to scale back greenhouse gasoline emissions, promotes small hydropower and streamlines its assessment because of perceived decrease environmental affects.
Nations around the globe—from China to Brazil to the Balkan international locations of southeast Europe—have handed insurance policies selling small hydropower and matter its construction to a ways much less making plans and regulatory oversight in comparison to massive tasks.
Thus, local weather and effort insurance policies are selling funding in small hydropower. However how a lot will the next funding give a contribution to local weather and effort goals? The case of India is instructive. India’s renewable power function does now not depend massive hydropower towards its overall objective, but it surely does come with small hydropower, outlined as tasks not up to 25 MW of capability. The coverage turns out to wait for what the revel in in Switzerland already demonstrated: the whole contribution from small hydropower will probably be, neatly, small.
India plans for five GW of small hydropower out of a overall renewable objective of 175 GW. Despite the fact that each and every undertaking constructed used to be the utmost 25 MW, that will require 200 new dams to offer simply three% of the renewable objective; since the proliferation of dams following incentives will most likely come with many which can be a lot smaller than 25 MW, India may just see 1000’s of latest dams for what’s going to quantity to a rounding error in its nationwide power provide, at the same time as research display that small hydropower dams are having higher than anticipated environmental affects.
Taken in combination, those effects and tendencies counsel that a lot larger warning and attention is had to information making plans and coverage for small hydropower.
Even though small hydropower could also be suitable for some eventualities—and there may be substantial possible for innovation for small hydropower added inside present infrastructure—insurance policies that advertise the proliferation of small hydropower with restricted oversight will most likely produce important cumulative affects for insignificant increments of extra era, whilst probably diverting sources clear of more practical answers. Failure to beef up insurance policies that govern small hydropower dangers the lack of tens of 1000’s of kilometers of wholesome streams and rivers with little or no electrical energy to turn for it.