Hydropower is one of the oldest power sources in the world. Power is generated when flowing water turns a wheel or turbine. It’s renewable, creating no air pollution and no toxic byproducts. In addition, the global weighted average cost of hydroelectricity in 2018 was USD $0.047 per kWh, making it the lowest-cost form of energy in many world markets.
Such a reliable (and inexpensive) power source doesn’t get the headlines that some of the newer (and more visible) technologies can get. Still, hydropower is a form of energy with great potential — not just for new facilities of varying sizes, but also for upgrading existing hydro projects. Before looking at those future projects, let’s first understand the projects we have now.
The Water Cycle
While our planet is covered to a great extent by water, hydroelectric power is still affected by climate. This is because it is dependent on the water cycle.
The water cycle starts with solar energy heating water in rivers, lakes, and oceans, causing evaporation. That evaporated water eventually condenses and falls as precipitation, most often as rain and snow. This precipitation collects in streams and rivers, which empty into oceans and lakes.
So, if there’s any change in the velocity of the water cycle at any given time, as happens when there is a drought, for example, the electricity generated by a hydroelectric plant is affected. The major drawback of hydroelectricity is its dependence on the consistency of the water cycle in a project’s given area.
Types of Hydroelectric Facilities
The overwhelming majority of hydro projects in the US and the world are not electricity generating. They are used for:
- Farm/stock ponds
- Flood control
- Water supply
These existing facilities provide a great opportunity to bring electricity online at a fraction of the capital expenditure it would take to create a new equivalent-sized facility. They represent a global opportunity to increase renewable generation by gigawatts.
The two types of power-generating facilities you are most likely to see are impoundment facilities and diversion facilities.
The Hoover Dam in the United States is the example many might think of in reference to impoundment technology. The water is impounded, usually in a type of reservoir, and is then released slowly through passages (called penstocks) that contain turbines.
A diversion facility channels a portion of a waterway through a canal and uses the natural decline of the waterway to produce energy. This is a lower impact form of generation and does not require the use of a dam.
A third type of facility functions less as a primary means of energy generation than as a type of “battery” that is charged up during off-peak periods and then discharged during peak periods.
The principle behind pumped storage is financial, not electric. At off-peak periods of electrical use, excess generated energy can be stored by pumping water (sometimes by using a type of turbine that can be turned into a “reverse” mode) to a higher elevation. At peak times of electrical use, that water at a higher elevation can be released, turning turbines to create electricity. Because it takes more electricity to pump water to a higher elevation than can be generated by water flowing downhill, pumped storage is a net consumer of electricity. However, because of the difference in the cost of that electricity, it’s often a net profit center for utilities that ensure that water is only pumped into the higher elevation storage facility at rates that are less than what is charged for the electricity generated when the water comes back down.
If all the positive aspects of hydropower sound too good to be true, it’s only because we haven’t yet spoken about an important aspect of it that is getting more and more visibility these days: sustainability.
While it is true that hydroelectric facilities don’t have the same ongoing environmental impact that other forms of power generation have, it’s also true that the initial impact of the plant itself cannot be understated or underestimated. That’s why it’s important to think through a hierarchy of actions when dealing with those impacts:
- Avoid — use site selection and project design to prevent negative or adverse impacts
- Minimize — if negative or adverse effects cannot be avoided, alter operational controls or implement environmental flows to minimize those effects
- Mitigate and compensate — apart from minimizing negative effects, projects can proactively mitigate and compensate for the changes to the environment, e.g. restoring lost habitats or re-establishing biodiversity in the affected area
Other examples of mitigation and compensation abound in various projects around the world, including:
- Sediment and erosion management
- Modifying dam operations
- Building fish hatcheries
- Controlling the water temperature and oxygen levels of outgoing water from dams
- Fish passage facilities
- Conservation and remediation of land
These last two examples are passions of Natel Energy, whose CEO, Gia Schneider, recently appeared on the Siemens Energy Podcast. Gia originally was exposed to sustainability and clean energy from the investing and financing side, but her passion for the climate and the environment led her to co-found Natel, which “develops sustainable, climate-resilient hydropower enabled by fish-safe turbines and powerful predictive analytics.”
Fish Passage Facilities
Natel manufactures a proprietary Restoration Hydro Turbine (RHT) that has a greater than 99% survival rate for fish that pass through it.
This starts with a low number of blades in the RHT, which reduces the likelihood of a strike. Further, the blades are blunt, slanted, and leading, deflecting the fish away from the blades. The slant of the blades ensures that even if there is a strike, the severity will be less, which leads to high runner RPM and reduced generator cost.
Even more exciting, the RHT is designed to replace turbines at existing hydropower facilities, allowing those facilities to take advantage of a significant improvement in environmental performance without any major changes to existing infrastructure or decrease in output. Indeed, because many of the units at existing facilities are often quite old, a retrofit with the RHT could boost efficiency and energy output.
Prior to the RHT, the most frequently used technology for the protection of fish was a screen and redirect approach: a fine screen in front of a traditional turbine and a separate passage for fish. However, those screens must be cleaned and maintained regularly, as they will accumulate debris which can lead to conditions that would harm the fish. They are also expensive, sometimes costing more than the turbine itself. Finally, because they impede water flow, they can reduce the amount of power produced by the plant.
Conservation and Remediation of Land
The name for the RHT also embodies a philosophy for the team at Natel Energy. For them, Restoration Hydro is just as much about generating energy and creating economic opportunities as it is about restoring watershed and ecological function.
One of the reasons that watersheds have to be restored is their degradation worldwide, particularly in the US:
- 55% of US waterways are degraded
- 71% of US waterways in the deep South and Northeast are degraded
- 24% of rivers classified as degraded were classified as such between 2004-2009
What Makes a Waterway “Degraded”?
A degraded waterway can face one or more of the following challenges:
- Erosion — Waterflow can destabilize riverbanks which makes it difficult for natural vegetation to become sufficiently rooted. Erosion is a self-reinforcing process: as waterways become wider and deeper they confine more of the stormwater stress within the channel itself, rather than distributing that force over a flood plain.
- Sedimentation — Sediment can fill in spaces between rocks and settle on the stream bottom, causing habitat loss for fish and aquatic invertebrates.
- Lack of baseflow — Baseflow in streams is usually made up of water that soaks into the ground, making its way slowly to the stream channel. In many situations, about one-third of the total flow in a waterway is runoff and the rest is baseflow. When there is a dramatic fluctuation in flow between dry and wet weather, the waterway is described as “flashy,” having little or even no flow during dry weather and very heavy flow during wet weather.
- Warmer water temperature — Warmer water can have a lower dissolved oxygen capacity, which leads to environmental stress for aquatic life.
- Excessive nutrients — While it might seem odd for there to be such a thing as “too many nutrients,” in an aquatic ecosystem, those nutrients can lead to harmful algae blooms. While those blooms produce a lot of oxygen during the day, they consume dissolved oxygen during the night, causing major oxygen variations, which are unwelcome fluctuations for the other life forms in the water.
Natel rightfully believes that not only should these waterways be restored, but also that that restoration makes sense economically. This leads to power generation, environmental restoration and preservation, and economic value.
While Natel Energy backs the Restoration Hydro approach in their technology and outlook on the environment, they also believe in the importance of distributed power.
This means extending existing controls and power electronics technology. Instead of using single, large dams, new projects can be decentralized across multiple, smaller projects. Big dams lead to fragmented rivers. Fragmentation stops fish and sediment from moving naturally through a river system, which leads to the degradation of waterways we discussed above.
Distributed energy is also investable, with $110B in estimated investments in Distributed Energy Resources (DERs) between 2020-2025.
While we’ve mentioned a lot of what Gia Schneider and her team at Natel Energy have been working on, there are many other exciting projects in development. What everyone can agree on is that hydrogen doesn’t face political or ideological resistance, in part because it’s already installed in so many places around the world.
Beyond what’s already installed, the potential for greater installations is astonishing. According to a 2017 study, an estimated 52,000 TWh/year across nearly 12 million locations could provide up to 33% of the worldwide energy demand. The current production of hydrogen only provides 3%.
The main task in the growth of hydropower is the education of utilities and consumers with knowledge of the possibilities that exist — not only to make hydropower a larger part of an area’s energy portfolio, not only to create jobs and economic value, but to restore and preserve the environment which is providing the energy in the first place. Those are principles everyone can get behind.
What everyone can agree on is that hydrogen doesn’t face political or ideological resistance, in part because it’s already installed in so many places around the world.