Lucy has farmed his patch of this green and pleasant land for 10 generations. she looks forward to handing the mantle over to her daughter who is currently 4 years old, when she retires. On her land is a low rolling hill known to the family as ‘canapy hill’ because it is always windy. She thinks this will make a great place for a wind turbine.

The wind turbine installation company thinks they can install one of their 6 kWp turbines on the site and it will achieve a 27% capacity factor there. The cost they quote is £25,000. The equipment has a life expectancy of 20 years. Over the first 10 years they expect O&M costs of £300 per year rising to £350 per year in the second 10 years.

Lucy decides that she can raise £10,000 from the family savings but will need to borrow £15,000 for the project. The bank offers him a 10-year loan at 8% interest.

The farm has a smart meter and, based on the half-hour data available, lucy estimates that she will achieve a 70% self-consumption rate as his milking parlour and refrigeration on site offer a reliable demand spread across the day.

Her electricity tariff is 30p per kWh, and she has a deal on offer for exported electricity of 6p per kWh.

Lucy decides to set a discount rate of only 4%. Her accountant points out that farmer lucy might not even live long enough to see out the end of the project lifetime and she should be more concerned about the poor milk prices being offered by the supermarket for this year’s milk output, so she suggests a discount rate of 15%.

i. Calculate the annual output of the turbine

ii. Calculate the annual savings on imported electricity

iii. Calculate the annual income from exports and hence the total annual income

iv. Calculate the revenue costs paid each of the first 10 years and each year of the years 11–20

•  calculate the NPV of this project in the table below, using the two suggested discount rates for its complete lifetime.

Year Income NPV 4% DR NPV 15% DR Expenditure NPV 4% DR NPV 15% DR

0 

1 

2 

3 

4 

etc