ALL ROADS TO SUSTAINABLE ENERGY LEAD TO THE SUN where people don ’ t rely on the support of remote infrastructure , like connectivity to a centralised electricity transmission line , but instead use a stand-alone independent power supply . Such systems are perfect for people living in rural areas . Access to energy should be a basic human right for the 620 million people across Africa deprived from it . To achieve this , one should look beyond the grid for future power solutions .
In my years of teaching an advanced level sustainable energy course , it ’ s clear that the ‘ sustainable energy ’ solution requires a multidisciplinary approach and needs expertise from the fields of chemistry , biophysics , biology and materials engineering .
For example , photosynthesis is nature ’ s solution to sustain life and its complete understanding touches many disciplines . Can science learn from it to provide a sustainable energy solution ? Yes , through a process called artificial photosynthesis . Large-scale photovoltaic ( PV ) panels dot the landscape in solar farms . Can we imagine transparent solar cells with the look of glass that can be brought to the city ? The answer is yes .
Say yes to the sun
Energy is the most important resource for humanity and solar energy is the ultimate energy source . The sun as a solar energy source has a number of advantages : it is abundant , it is essentially inexhaustible , and it doesn ’ t discriminate but provides equal access to all users .
Earth presently consumes energy at a rate of about 17.7 trillion watts ( 17 terawatt , TW ), that would reach 30 TW by 2050 assuming a similar population growth rate . The solar energy irradiating the surface of the Earth is almost four orders of magnitude larger than the rate our civilisation can consume it . This is obviously more than sufficient if harnessed properly .
The energy potential of the sun is 120,000 TW at earth surface . More practically , assuming that only 10 % efficiency and covering less than 2 % of earth surface would get us 50 TW ; Wind is at 2-4 TW at 10 meters ; nuclear 8 TW , build one plant every 1.5 days forever - due to decommissioning ; biomass 5-7 TW , all cultivatable land not used for food ; geothermal 12 TW .
The solution should thus be clear : focus on the sun , nothing else gets the required numbers . The solar and wind duo has been considered a viable option at least for Africa ’ s future . The challenge is that solar energy only becomes useful once it ’ s converted into usable energy forms like heat , electricity , and fuels .
Below are two state-of-the-art new technologies that convert solar energy into electricity or fuels .
New technologies
Black solar photovoltaic ( PV ) panels are the most familiar to generate electricity . A game changer will be a new technology where such PV panels are transparent . This could then replace regular glass , wherever one finds glass . For example , on large buildings , the vertical “ glass panels ” can literally become the source that powers the building .
The solar company Onyx Solar has already demonstrated proofof-concept by applying PV glass for buildings in 70 projects and in 25 different countries . Its only current competitor , Ubiquitous Energy focuses more on mobile devices . On a mobile phone , the glass screen will become the power source , potentially making batteries redundant .
In simplest terms , photosynthesis is a process where green plants use the energy in sunlight to carry out chemical reactions . One such reaction is to break water molecules into its constituent parts of oxygen and hydrogen .
Artificial photosynthesis is a process that mimics parts of natural photosynthesis to suit our needs , like forming hydrogen . And because hydrogen is considered the fuel of the future , a large research focus is to capture and convert sunlight into energy with storage of hydrogen .
Say no to nuclear energy
In South Africa , the nuclear energy landscape has been tainted by political greed , rather than scientific reasoning . Fortunately , in April 2017 all further developments for a nuclear future were halted by a high court .
Let us not repeat the deadly sins of considering nuclear power as an option , but remind ourselves of two consequences .
It takes 10 years and billions of rand to commission a nuclear power station , let alone eight . Once commissioned , such stations don ’ t last forever , but after 50 years has to be decommissioned again , costing the same amount in time and fiscal .
Suppose South Africa is a country with stockpiles of enriched uranium and nuclear plants , such utilities become primary targets for terrorists and are expensive to safeguard . Why even take the risk ?
It ’ s now 31 years since the Chernobyl nuclear disaster . It devastated Ukraine and the 2,600 square kilometres of surrounding land is still considered unsuitable for humans .
A colossal radiation shield is now concealing the stain on that landscape . Is such a risk worth it for South Africa when the sun has so much potential ? -
WERNER VAN ZYL Associate Professor of Chemistry , Lecturer in sustainable energy , University of KwaZulu-Natal
2017 | Business Times Africa 59