A typical island : 100% renewables in sight

Matching the load with renewables makes the case for a mix

Introduction

The location is an island in the Atlantic Ocean and one of the more remote places on this earth. The local utility company has put out an RFP for the installation and operation of renewable power plants on the island grid. Applicants should act as Independent Power Producers (IPP) and propose a Power Purchase Agreement (PPA). The island has raised the bar proclaiming the goal is to be all renewables by 2022, with the addition of first 2MW and finally 5MW of generation capacity. In addition, a price cap has been set on the electricity delivered of 0.154 USD/kWh.
Current generation capacity is mainly diesel-based (7.6MW) with about 1MW of wind (of which about half is reaching its end-of-lifetime), PV capacity is planned to increase to about 0.6MW. The island’s electrical system has a current peak load of about 2MW; total electricity consumption in 2016 was 9.7GWh (for 4,500 inhabitants) mainly for residential and commercial use. The island electricity consumption is poised to increase with the construction of an international-airliner-ready airport and the expansion of tourism: peak load is expected to increase to about 5MW.
The island has very good wind resources, with average wind speed of 6.9m/s, and a global solar irradiance of 5.6kWh/m² per day. Dominant winds are from the SE, and are fairly constant throughout the day.

Analysis

This case is a very typical example of the energy transition on remote locations: the shift away from fossil fuels and the ambition to eventually have an all-renewable electricity supply. More and more often such “overhauls” of remote electrical systems are done based on PPA’s made with an IPP who takes charge of the assets in a Build-Own-Operate model.
XANT simulated this island case in HOMER Pro to assess the challenge of achieving the targeted PPA price and the optimal system configuration. The HOMER Optimizer finds the system configuration with the lowest Net Present Cost (NPC): about 5MW of newly-installed PV capacity, 2MW of wind (6 x XANT L-33) and a 14MWh Li-Ion battery. The table below shows the LCOE and renewable energy fractions of the various system configurations:

[1] The HOMER Pro® microgrid software by HOMER Energy is the global standard for optimizing microgrid design in all sectors, from village power and island utilities to grid-connected campuses and military bases.

 

The graph below gives an overview of the relative contributions of the solar and wind assets to the total electricity generation. Utility-scale PV can deliver electricity at about 6.18 USD cent/kWh on the island while the XANT L turbines achieve a LCOE of 7.09 USD cent/kWh.

Conclusions

  • At current market prices of PV, wind and batteries the system with the lowest Net Present Cost is already an all-renewable system with PV providing 58% of the energy and wind 42%.
  • This optimal configuration can deliver electricity at almost half the cost of the existing system (USD 0.202 per kWh vs. USD 0.388/kWh assuming a landed diesel cost of USD 1,28 per l).
  • Mixed-technology system perform better than solar-only systems: adding wind to the system reduces the size of the battery, and at the same time enables an all-renewable solution.

Not only in financial terms is a mixed system to be preferred: also other constraints favor adding wind to island electricity systems. The intermittency of PV on cloudy days is easier to mitigate when not solely relying on solar power. And in space-constrained locations, the total footprint of the power generation assets obviously is of importance.

At XANT we manufacture turbines for exactly these locations: the limited craning capacity of the island and difficult road access, make the logistics of large MW-size turbines very costly. The tilt-down towers of the XANT M and XANT L allow for crane-less erection and maintenance done at ground level for all O&M interventions avoiding any crane cost during the complete lifetime of the turbines. The JEEP (Just Enough Essential Parts) design philosophy ensures maximum availability on such remote locations.

Disclaimer

Any information regarding pricing of XANT products is purely indicative and does not constitute by no means a binding offer on behalf of XANT.

Any information regarding pricing of other technologies is purely indicative; XANT is not linked to any supplier of complimentary-technology suppliers.