Renewable technology are on the political agenda as never before, wind, wave and solar power are the new words all politicians’ vocabulary. However, hydropower, which was the foundation of the industrial revolution and as such the historical basis for the modern society, is not mentioned with the same frequency. Hydropower technology is not “sexy” enough. Why is it so? There are most likely more than one answers to this, but I believe that part of the reason is the hydropower industry’s lack of ability to take on technology achievements from other technology areas. The hydropower industry, to put it mildly, is somewhat conservative.
To make an analogy. When the oil and gas industry concluded, that the offshore platform solutions would not be a profitable solution for the development of new oilfields, subsea technology emerged. Still expensive, but far cheaper than the old platform based technology. When the focus in Norway changed from large hydropower plants with tens and sometime hundreds of MW installed, to small hydropower, less the 10 MW, they changed the controller from mechanical to electrical. Everything else stayed the same, just a downscaled version of the large power plants. Not, really at quantum step in evolution.
Overall, the growth of renewable energies will for all technologies, hydropower included, be depended on the electricity price and the investors’ prediction of the obtainable price in the future. The necessary investment pr. produced unit (kWh) will obviously be a factor that will be included in the analysis of the profitability of the investment. This is basic economics, and the need for profit will never change. The profitability, regardless of the type of renewable or other type of energy, is dependent of the following factors.
- Investment pr. produced unit (kWh or MWh)
- Electricity price pr. produced unit (kWh or MWh), present and future
- Operational and maintenance cost
In addition, there are risk factors that create uncertainty to the analysis. How much will it rain, will it be dry years or will it be wet years. How many sunny days, etc. Every source of energy will have its uncertainties, but here focus will be on hydropower. Taxes and electricity prices are out of the developer’s control. However, the developer will always be able to find predictions and estimates are available. However, The Developer can influence the size of the investment and the operational and maintenance costs, active costs or passive costs.
- Civil engineering works, i.e. dams, pipes, gates, powerhouse etc.
- Operational and maintenance cost
- Grid connection
- Electro/mechanical equipment, i.e. turbines, generators and accompanying equipment
The active, cost is the only ones that will influence the future earnings. The passive is necessary, but will not, except in very special cases, influence the future earnings. However, there is an obvious link between the selection of electro/mechanical equipment and the maintenance and operational costs. The developer should always minimize the passive costs, and rather spend money on the active elements. Of course, the economics still have to add up. As there is requirements set by the authorities, there is not a total freedom in specifying civil works. Remarkable enough, many developers, even professional developers, do not comply with this somewhat elementary economical principle.
Efficiency of a turbine will always deteriorate over the lifetime of the turbine due to wear, corrosion, cavitation or other causes, of which, some can be eliminated and some, which effect can be delayed. As it affect future earnings, careful considerations is necessary when selecting technology and configuration of a power plant. In addition, the operational plan of the power plant will also effect the selection of technology.
- Investment costs, both infrastructure and equipment
- Effect on future earnings
- Refurbishing costs, i.e. repatriated to its original condition
- Maintenance cost
In addition to the traditional turbines Pelton, Francis and Kaplan operating at constant speed, there is available a number of other possible selections which can be more suitable and more profitable for a specific project depending on the project’s characteristics. Including, but not restricted to the following technologies;
- Variable speed operation of medium and low head turbines, and even high head turbines with long penstocks
- Direct coupled generator
- Belt driven high speed generator
- Archimedes screw
- VHL turbine
- Low Head turbines with integrated generator
- Submerged generators for open pit power stations for both synchronous and variable speed operation
The main bottleneck for the implementation of these “innovations” in both new power plants and power plants under modernisation is mainly the same conservatism of the hydropower business. However, also the research establishment is in my experience to blame. The research establishment is too much focusing on the optimization of the traditional turbine types, and do not know enough of the technology development in other areas of technology to contribute to the development of new solutions.