Electricity prices on islands are among the highest in the world.[i] That’s because many island societies rely heavily on imported diesel, natural gas, and coal to fuel their power plants. When islands increase the amount of electricity produced from renewables, they considerably decrease their levelized system costs, reduce emissions and become more energy independent.[ii] According to one estimate, small developing island nations would save at least $3.3 billion annually if they switched to renewables.[iii] The biggest problem standing in the way is intermittency. While many are placing their hopes on storage to solve this problem, here are a few more sustainable solutions.
#1. Install a renewable core
Most islands that are moving into renewables are doing so by complementing their existing electrical infrastructure. But the most effective way for islands to achieve long-term energy independence is to replace the core of the system with a green baseload. The core of the electrical system in the Faroe islands, for example, is a combination of oil-fired thermal power plants and hydropower. To reach their goal of producing 100% green energy by 2030[iv], the Faroese electrical company SEV plans to shift the emphasis entirely to the hydropower power plants with the help of pumped storage systems.
Another approach would be to install modular geothermal heat power plants like developer Varmaorka[v] has on Iceland. Now that geothermal electricity can be harnessed from lower temperatures, this will become a cost-effective solution for many island communities. It would be especially ideal in volcanic island groups, like the Canaries, where modular plants are less risky should they need to be relocated.
#2. Low-temperature waste heat recovery
When providing a non-intermittent green baseload like heat power is not an option, one way to address the fluctuations in supply and demand caused by wind and solar is through waste heat recovery. This solution can take a number of forms.
On the island of Samsø in Denmark, the islanders have actually managed to reach negative annual emissions per in habitant (!) partly by transitioning away from oil-burning furnaces to biomass.[vi] On Samsø the biomass is primarily used for district heating, but adding waste heat recovery modules would offer the flexibility of creating additional power when their heating needs are met, or in the summer months when heating is unnecessary. The island may be one of the few on the planet that exports surplus electricity back to the mainland. That said, there are times when it relies on its underwater cables for backup – a situation that having a heat recovery system could likely eliminate.
A no less critical step is to combine waste heat recovery with traditional generators. [vii] To my knowledge, for islands that do have a geothermal heat source, or a mix of renewables like on Samsø, this is the most logical and quickest way to lower emissions. Diesel and methane gensets[viii] expend about 45% of their energy in heat – heat that the waste heat recovery process can use to reduce fuel consumption or turn into extra electricity.
Finally, waste heat recovery could also be used during the bottoming cycles at large-scale geothermal plants. On the Azores, the goal is to reduce carbon emissions by 20% by next year. This could be a great way to ensure that they meet this goal, while simultaneously increasing their electrical output.
#3. Storage: the final frontier
Most articles on this topic might put storage at the top of their list. It is perhaps the most anticipated development when it comes to solving the world’s the power needs. Yet while it is possible to install storage and balancing systems, like the one Tesla has installed in Samoa,[ix] such solutions are expensive. They are also difficult to scale to islands with large populations. Here again, I believe that heat power could a role to play by combining with solar thermal or underground reservoirs. In an ideal world, a carbon-neutral battery source that relies on the sun or geothermal heat power would make the recovery of lithium, lead and other natural resources unnecessary and bring islands even closer to autonomy.
Do you live on an island? Do you agree that intermittency is the #1 thing preventing your community from “going green”? Have you considered some form of heat power? Contact a member of our team to discuss options.
[i] Caribbean islands experience some of the highest electricity prices in the world. There is a strong correlation between islands with reduced energy prices and islands that are switching to renewable energy. https://visionenergy.com.fj/providing-energy-small-island-developing-states/
[ii] “Levelized system costs for electricity generation decrease considerably with increasing renewable energy penetration, up to an optimal point in the range of 40% to 80%.” https://www.sciencedirect.com/science/article/pii/S0306261918308249
[vi] Imagine, an other island that actually sends electricity back to the mainland!? http://nordicway.org/article/the-challenge-of-renewable-energy-in-island-communities/
[vii]This article mentions MAN Diesel & Turbo that was state-of-the-art when it was installed in June 2015 on the Caribbean island of Guadeloupe and designed to handle 45% of the island’s power needs. Installation of a heat recovery component would increase plant efficiency and output, and reduce emissions. https://www.powermag.com/marooned-how-island-power-systems-keep-the-lights-on/?pagenum=4