Possibly the best known form of renewable energy is solar power; that is, power generated from solar panels. These are cells which absorb light energy from the sun and convert it into either heat or electrical energy. There are broadly speaking two types of solar panels: photovoltaic (converts light to energy) and concentrated solar power (harnesses heat energy). Photovoltaic or PV cells are comprised of a sandwich of semiconducting materials, silicon typically, which are oppositely charged creating an electric field. Phosphorus is often used to generate a negatively charged layer and boron is used to generate a positively charged layer. When a photon of light hits the PV cell, it ‘knocks’ an electron free and as a result of the electric field, this electron is pushed out of the silicon junction where it is collected by metal conductive plates and allows the electrons to flow as electricity. Concentrated solar power, CSP in short, involves using a mirror to focus the light from the sun into a concentrated beam which heats a liquid such as oil or molten salt. This heated liquid is then used to heat water, creating steam which powers conventional turbines and generators to make electricity.
Solar panels have always been a popular form of renewable energy, and their use has been rapidly increasing worldwide in the last decade. While PV is much more popular than CSP with a worldwide installed capacity of roughly 200 GW compared to 5.5 GW, CSP capacity grew ten-fold from 2004 to 2013. Growth projections by the international energy agency show that the installed capacity for PV power could reach 3000 GW by 2050 producing 4500 TWh per year of electricity, comprising 11% of total global electricity generation. CSP is also likely to continue growing at a rapid rate. This enormous growth could also be surpassed as many new technologies are developed with increasing efficiency and lower costs.
One of the most exciting prospects for the solar industry is the genesis of floating solar farms, also known as ‘floatovoltaics’. PV Solar panels are placed on bodies of water, either inland or offshore and have numerous benefits. Firstly, they don’t occupy large areas of land like regular solar farms. They are also more compact than land-based solar farms as there are no fixed structures associated with floatovoltaics and thus their installation and decommissioning is much simpler. The panels are naturally cooled by the water on which they are placed, which increases their production efficiency as solar panels are prone to overheating. Furthermore, it has also been noted that the panels shade the underlying water, reducing evaporation thus conserving more water and also slowing down algal blooms which are associated with large scale fish kills. This technology was debuted in Japan in 2007 and is rapidly growing as an attractive strategy to mitigate against climate change and reduce carbon emissions.
You may be sitting at home, reading this and asking yourself how that would work in Ireland. Sure, it makes logical sense that countries like Australia would deploy these tactics to combat climate change, but here in miserly Ireland it would simply be a waste of time. You might be surprised then to hear that earlier this year the start-up company Solar Marine Energy received a grant of €200,000 in partnership with UCC to develop the technology of floating solar panels to power electrolysis, producing hydrogen which can be stored and used when required. Then in August, the company announced it has plans to build a 1.5MW floating solar farm at Ringaskiddy, Co. Cork which will generate electricity for the nearby MaREI centre. It is hoped that this plant will be operational in 2020 and will demonstrate the effectiveness of the technology.
The climate action plan released by the government during the summer has given targets of achieving 1.5 GW of grid energy from solar farms by 2030. There is also a grant scheme in place which covers up to 30% of the cost of solar panel installation for private homes which aims to encourage more people to retrofit their homes, with plans to enable citizens to sell excess electricity back to the grid by 2021. There has, however, been controversy with this scheme. While this is good news, we can definitely aim higher than 1.5 GW. For a start, the word ‘solar’ is only used 15 times in the total of the 150-page climate action plan document. Considering it is one of the governments key strategies for mitigating against climate change, you would be forgiven for thinking that they would have at least fleshed out their plans somewhat more thoroughly. Secondly, although Ireland is normally perceived as a grey, overcast country with small amounts of yearly sunshine and therefore not suitable for solar energy, it is visible light rather than direct sunlight which powers PV cells. Ireland has similar irradiation levels to Denmark, where as of 2016 they had a total installed capacity of 900 MW PV panels. By comparison, Ireland had 5.1 MW installed capacity in the same year.
According to the international energy agency, enough sunlight hits the earth in 90 minutes to provide the global power demands in a whole year. The potential for solar power is immense. It will be exciting to see further development in this sector and the many innovations which will be developed in the years to come. Let’s just hope that Ireland keeps up with everyone else.