Discussion on the Feasibility of Micro-hydroelectric Power Generation at Agricultural Irrigation Facilities in Hokkaido

 Figure 1: Micro-hydroelectric

 power generation

Table 1: FIT procurement price under

micro-hydroelectric power generation

(click to enlarge)

      Figure 2:            Figure 3:
       Typical water      Typical water
       discharge at        discharge at
       agricultural         agricultural
       irrigation             irrigation
       facilities              facilities
       outside               in
       Hokkaido            Hokkaido

(click to enlarge)

Figure 4: Profitability of

micro-hydroelectric power

generationat agricultural irrigation

facilities in Hokkaido

(click to enlarge)

Table 2: Calculation of power

generation unit cost at
agricultural dams

(click to enlarge)

　　　　 　　　　

Issues of Introducing Micro-hydroelectric Power Generation in Hokkaido

  Micro-hydroelectric power generation (Figure 1) has been promoted with a view to maximizing locally based renewable energies. The power is generated by using the head of water in agricultural irrigation facilities. In July 2012, the feed-in tariff (FIT) system for renewable energy came into effect, more than doubling the procurement price of micro-hydroelectric power compared to the pre-FIT period (Table 1). This has raised expectations for micro-hydroelectric power generation at agricultural irrigation facilities, which has not been widespread in Hokkaido. Outside Hokkaido, many facilities have enough water flow for hydropower generation throughout the year (Figure 2). However, agricultural facilities in Hokkaido use very little water from September to April; hence, power can be generated only from May to August (Figure 3). When starting a project for micro-hydroelectric power generation in Hokkaido, profitability needs to be carefully evaluated beforehand.

Evaluating Profitability by Calculating the Unit Cost of Power Generation

  To verify the economic feasibility of micro-hydroelectric power generation that operates only during the irrigation season, the Irrigation and Drainage Facilities Research Team of the Civil Engineering Research Institute for Cold Region (CERI) has calculated the unit cost of micro-hydroelectric power generation based on the design dimensions of agricultural water channels (open channels and pipelines) and agricultural dams in Hokkaido. Then, we compared the calculated unit cost with the FIT procurement price. The calculation for this study enables greater accuracy than conventional methods for calculating the unit cost of power generation. For example, the water head available in a dam for power generation is estimated from the past reservoir levels.

Evaluating Profitability by Calculating the Unit Cost of Power Generation

  Figure 4 shows the ranges of water discharge and head of open channels, pipelines and agricultural dams that ensure profitability in micro-hydroelectric power generation. It was assumed that 50% of the facility construction costs were subsidized. As the red dots in the figure show, at least a 10-meter effective head is required to make power generation profitable, regardless of the discharge. As the head within an open channel is only a few meters, it is difficult to implement micro-hydroelectric power generation at open channels. In contrast, agricultural dams and pipelines with at least a 10-meter effective head may be suitable for micro-hydroelectric power generation.

  Table 2 shows the calculated unit cost of micro-hydroelectric power generation at agricultural dams that have relatively advantageous conditions for generating power. The calculation assumes that there are no subsidies for construction. The calculation proves unsubsidized power generation to be profitable in some cases where the unit cost of power generation is below the procurement price.

  In light of this, several agricultural dams in Hokkaido may afford profitability in micro-hydroelectric power generation. As there are only a few micro-hydroelectric power generation facilities in operation in Hokkaido, it is necessary to start operation with the facilities that were proven to be profitable in this study and to make successful results at those facilities. It is also important to continue the operation, to accumulate findings of how power generation addresses the various problems unique to Hokkaido and to incorporate those findings into future micro-hydroelectric power generation systems.

(Contact: Irrigation and Drainage Facilities Research Team(CERI))