Friday, January 22, 2010

Non-Storage Hydro aka Run of the River

Non storage hydro is also referred to as run of the river and micro hydro. It is the best term to describe how the power is generated. The main aspect of non storage hydro is not size of the project but the fact there is no way to store water for production of power. The use of the term microhydro is not an accurate term and neither is run of the river.

Storage hydro facilities work on the idea that a large reservoir can store water for year round consistent power production on a large scale. The spring run off will take the reservoir to full pool and then the level is drawn down over the year as needed. The reservoir acts as a system to store the power until it is needed.

Non storage hydro has no capacity to retain water for later dates, it has no capacity to store power. This means that at the moment non storage hydro can not by the sole source of electrical power as the amount of power that can be generated varies during the year. When looked at in isolation, a specific project could have periods when it can not produce energy and therefore can not be considered firm supply on an ongoing basis. This all changes once there are a large number of sites throughout different parts of BC.

Non-Storage Hydro is the Internet of Electrical Production
The internet functions well not because any one part of this global network can carry all of the traffic all of the time, but because it is a system with thousands and millions of different nodes and routes and thereby allowing the internet to function well even if parts of it are down. This is the analogy one needs to think of when considering non storage hydro in BC. The overall generating capacity of non storage hydro in BC evens out as the number of generating sites operating increases. With more generating sites the electrical system can rely on more non storage hydro as firm capacity over the whole year.

BC has an abundance of locations on the coast for non storage hydro and the consistent year round rain fall to ensure year round generation in the vast majority of locations. Spring run off can occur from late March through to mid July in different areas of the province. Some people are concerned that non storage hydro sites can only provide power for part of the year. The data does not back this up.

Non Storage Hydro has very low CO2 Emissions
Non storage hydro has a very low carbon footprint, the lowest of any of the electrical production options available. The ongoing production of power from the facility has a very low CO2 output, mostly to do with the movement of people to and from the facility resources needed to maintain it. In some cases increased plant growth around the head pond may be enough to offset the ongoing CO2 contributions. The largest contribution of CO2 emissions comes from the construction of the facility.

The nature of the coast of BC and the needs of non storage hydro are well suited. Non storage hydro needs a decent year round water flow and steep inclines to provide a good head for the turbines. By their nature, the best sites for non storage hydro projects are in locations that are of lower values for wildlife and fish. In many cases, there are no fish near the project locations and the impact of the facility is not measurable downstream.

Energy Payback - Nothing is Better than Hydro
An important aspect of all energy production to be considered is the energy payback ratio – how much energy is generated for each unit of input energy. All hydro has a very high energy return rate, by far the best of any electrical generation. For a large scale storage hydro system the energy payback ratio is about 240 times as much energy is produced as was used to build and operate the facility. For non storage hydro this ratio is about 220 times. For fossil fuels it is only 1 to 7 times as much energy is produced as what is needed to build and operate. After hydro, the next best energy source is wind power at about 20 times the output when compared to the input. These numbers come from a July 2005 Hydro Quebec report by Luc Gagnon, there are other sources out there that confirm these numbers.

An energy payback of less than 1.5 means the system uses almost as much energy as it generates. Conventional coal fired power plants with CO2 capture and sequestration can be as low as this. This fact alone makes the idea that there will be a move to CO2 capture and storage by the coal fired power plants in North America unrealistic in the next 15 years.

BC has an Abundance of Sites
In 2007 there was a report by Kerr Wood Leidal on potential non storage hydro locations in BC. The report identified numerous ones with a combined annual generation of 50,000 GWh/yr. The report is a a useful ballpark to allow us to see what may be possible but it should not be taken as the final word on what is out there. The report missed out on many sites that are currently either in the planning stage or under development, the biggest example of this is the Plutonic Power Bute Inlet project.

The report was an overview of the province and made some assumptions that have not are not realistic, chief among them being that projects would not cluster and share infrastructure costs. The report was not able to make detailed and through design plans for each location and thereby missed many potential sites that are now under consideration.

As an example, Hawkeye Energy Corporation has identified and applied for 350 MW worth of sites for non storage hydro in less than one year. These sites have a potential for 1310 GW/h of generation. Many of their sites are located close to the Plutonic Power Bute Inlet project. As more projects are built and more infrastructure is there for them, the easier it is for smaller projects to piggy back on the infrastructure.

What we can take from the report and other sources is that BC has the capacity to develop more than 50,000 GWh/yr of non storage hydro over the next 15 years.

Non storage hydro has one more major advantage over almost all other green electrical generation technologies. Non storage hydro is economically viable now without any sort of market distorting government subsidies.

1 comment:

Anonymous said...

Pls. note that run of river may have an alpine lake, which gives it storage, without a dam and without flooding.

The main distinction is not if there is storage. The main distinction is where is the energy coming from. In a dam, water level is raised to create head. In run of river, the natural grade is used to generate head.

In the first case, by raising the water level, major flooding ensues.

Storage for regulation (timing) is not really the defining difference between the two technologies.

Thanks for the article.