Hydropower is the generation of electricity from flowing water – rivers, streams, ocean tides and currents. It is a clean, domestic, renewable energy source that is flexible and reliable. Many hydropower plants can ramp from zero to maximum output in as little as 10 minutes, providing rapid response power to support the stability of the electrical grid and thus modern economies.
During the Northeast blackouts of 1965 and 2003, and more recently this summer in California, hydropower plants were instrumental in quickly restoring power to the grid. Recent analysis suggests that hydropower resources can serve up to one-third of grid reserve requirements – critical support to aid the integration of wind and solar as we transition to a zero carbon grid (source).
Conventional hydropower design relies on large dams to create big reservoirs – this increases the concentrated amount of storage, which is good for power generation and water supply, but has resulted in fragmented rivers. This fragmentation blocks fish and sediment from moving naturally throughout a river system, and this can have substantial negative impacts on ecosystems and biodiversity.
But, what if we could harness the massive energy potential of our moving waters – estimated globally at 52,000 TWh/year (source), or more than three times all the electricity generated globally by fossil fuels in 2018 (source) – with a design philosophy that values environmental uplift and freshwater species, in addition to the existing benefits of hydropower?
The solution is a new approach to hydropower that is:
- Distributed → extend existing controls and power electronics technology, that is already adding new sources of decentralized generation to the grid to integrate multiple, smaller projects instead of a single large dam.
- Nature-inspired → extend concepts already used extensively in river restoration and green infrastructure to design projects that improve watershed connectivity and support or restore ecosystem service functions.
- Fish safe → design for >99% safe downstream and upstream passage of fish.
Fortunately, this new approach to hydropower is possible today! Interest in distributed energy resources (DERs) is growing rapidly and DERs are expected to attract $110 billion in investment between 2020 and 2025 (source). River restoration and nature-based approaches to water infrastructure development are increasingly recognized as a best practice that many water authorities and river managers in the US and the EU are legally required to use. Until now, the key missing ingredient was an economically competitive, hydraulically efficient and compact fish-safe turbine.
A fish safe turbine is critical for two reasons.
First, one might ask – why not just put some sort of screen in front of a non-fish safe, conventional turbine and direct fish around the hydropower plant? It’s certainly possible to do that, but fish screens are expensive – in some cases costing more than the turbine. They are also expensive to install, requiring larger intake structures. Finally, fish screens reduce the amount of power produced by the plant because they impede water flow.
Second, the new, distributed approach to hydropower is achieved at scale by multiple distributed projects installed in series along a single river, which are operated as an integrated virtual power plant. Thus,migrating fish need to pass multiple projects successfully to reach the ocean. What level of fish safety is needed to mitigate hydropower impacts on fish populations? A 90% safe passage probability through a single turbine might sound acceptable, but with 10 projects in a row, compounds to merely 35% – a devastating statistic for migratory fish populations. A 99% safe turbine passage probability is needed to ensure a cumulative survival rate of 90% for the same scenario. At 99.5% safe turbine passage, the cumulative survival rate after 10 projects jumps to 95%.
So, is it possible to make a turbine that safely passes over 99%, or perhaps over 99.5% of fish through it, without compromising on turbine efficiency? The answer is…YES! Check back next week for some exciting news on this front.
