Life has existed for millions of years before the development of electricity. All thanks to the giant nuclear fusion reactor at the center of our solar system, 'The Sun'. The Sun generates energy from its core, where hydrogen atoms fuse to create a helium atom, producing enormous amounts of energy in the process. This energy is essential for life on Earth. Sunlight is used by plants to produce food that is directly or indirectly the source of food for all living things; is responsible for the stations; its heat keeps water in its liquid form, which is fundamental for the existence of life; Sunlight is an essential source of vitamin D for the human body and for many other life-supporting processes that are directly or indirectly choreographed by the sun.

Figure 1: A representative image of the artistic representation of Solar Roadway

Its energy can also be harnessed and converted into electricity and heat. Solar panels made up of sets of 'photovoltaic cells' (photodiode semiconductors) that work according to the principle of the “photoelectric effect”. This effect produces the movement of electrons when light falls on the cell. The movement of electrons produces current giving rise to a potential difference and, therefore, electricity. Then there are solar concentrators that concentrate a portion of the sun's energy onto a smaller area using lenses or mirrors. The heat obtained from these devices is used to heat water to produce steam and drive turbines to generate electricity.

Solar Roadways is a currently trending innovation that focuses on replacing ordinary roads with structurally designed solar panels that can support the weight of vehicles as well as withstand other environmental conditions. They consist of solar cells placed under tempered glass. The energy received from these roads can power traffic lights, lights, signs, and also local homes. If successful, the entire road system (if not most) of a country could be transformed into a solar power plant. It can also provide a source of electricity to charge moving electric cars as an added advantage. Solar roads can reduce a country's harmful emissions by at least 50%, a number that cannot be ignored given the alarming rate of increase in global warming. SolaRoad in Krommanie, Netherlands, is the first solar-powered cycle path built in the world, opened in November 2014. In this article, we will discuss the economics of solar energy and the technology used in building solar roads.

Figure 2: Image of the first solar-powered road in Krommanie, Netherlands , November 2014

1 Solar Energy – Statistics

The Earth receives a fraction of the sun's energy every day, which we know as solar energy. In full sun, the Earth receives 100 Watts of solar energy per square meter. Assuming about 12 hours of sunlight per day for 365 days per year, the annual energy from the sun is about 438 KW-hours per square foot. There are 10,760,000 square feet per square kilometer, which makes available energy 4.7 Terawatt-hours per square kilometer annually. India covers about 3,000,000 square kilometers. Total electricity consumption in India for the 2014-15 fiscal year is around 850 TW-hours, which is equivalent to the solar energy received by just 180 square kilometers (approximately two and a half times the size of Mumbai). From this we can agree that the sun provides us with about 15,000 times more than average usage.

So what do these numbers mean? It shows that the sun gives us more energy than we actually need to survive without the use of non-renewable fossil fuels. But why hasn't the world taken advantage of this yet? The answer to this lies in the second law of thermodynamics. In simple terms, we cannot convert all the energy we receive from the sun into usable electricity. Current technology is limited in its efficiency and cannot provide a greater profit, which is a decisive factor in a country's economy. However, it is a global goal to develop cleaner energy resources, which motivates countries to join the solar race, channeling funds into research and development to make solar energy a more viable alternative.

Solar Roads

2 solar roads

Figure 3: Image showing Solar Roadways Inc., a startup from Idaho, USA

As previously mentioned, solar roads are structurally designed interconnected solar panels (which are approximately 12'x12' each) that replace conventional asphalt roads, parking lots and sidewalks. These can power small businesses, homes, traffic signals, smart roads and also act as carriers of data signals (high-speed internet, cable TV and telephone). This technology could replace the country's currently deteriorated electrical grids. Solar roads provide power to built-in LED lights that can display messages, illuminate roads, display warning messages in case of speeding or proximity to impact, closed road ahead, etc. to melt the snow and clear the roads. This will also increase the feasibility of using electric cars by providing charging stations. These smart roads, once installed, will pay for themselves, heal themselves and provide profits to an economy by eliminating dependence on fossil fuels. Using solar panels with 15% efficiency as an independent electricity source will provide 3 times the required power capacity.

Fig. 4: Image showing tempered glass cover with rough finish for traction on solar roads

2.2 Layers of Solar Panels

Solar panels are arranged in three basic units

1. Road Surface Layer

2. Electronic Layer

3. Base Plate Layer

The top layer will consist of photovoltaics on tempered glass. The important characteristics required are transparency (translucent), hardness and roughness. Roughness is necessary to provide traction so that the vehicle's tires turn without slipping. Each individual solar panel is screwed into connection with the bottom layer. This will make it easily usable. The LEDs and heating element will go into this layer. The next most important unit is waterproofing to prevent water leakage into the electronic unit below.

The Electronic layer consists of the microprocessor with supporting circuits (measurement, feedback and control units). This will control the heating elements (snow detection), charging (pressure gauges), lighting, communications and monitoring. Microprocessing units will be installed every 3.6 meters, making it a true “smart road”.

The base plate layer is the power transmission layer. The energy captured by the solar panels and collected by the electronic layer is distributed across the base plate layer. Data signals are also transmitted through this layer along with power to all homes and businesses connected to the solar roads. This layer is also waterproofed and weatherproof to prevent damage to the electronic layer.

Figure 5: Image explaining the basic structure of solar roads

2.3 Advantages and Disadvantages

– The main advantage of solar roads is that they are a renewable and clean source of energy.

– Solar panels have a lifespan of 30 to 40 years, while conventional asphalt roads have a lifespan of about 7 to 10 years (without monsoon damage).

– Can provide electrical access to remote areas that are far from power plants.

– Can also be placed near environmentally sensitive areas.

– Will provide on-the-go charging for electric cars if coupled to an induction hob.

– It will create a new job-generating industry.

– It will immensely reduce harmful emissions (by at least 50%).

– It will provide an intelligent means of traffic management (reducing accidents and traffic jams).

– High installation and initial maintenance costs.

– Low average efficiency of solar panels.

– Difficult to implement in poorer countries due to high initial cost.

– Rubber build-up from tires (due to frictional wear) can block sunlight.

3 Is there a better future in store for us?

At the current rate of fossil fuel consumption, we will hardly be able to last a few decades. If we don't do something about it, human civilization will return to the dark ages and, as an additional wound, our environment will be irreparably damaged. The polar ice caps will melt, the oceans will rise, the forests will disappear, the ozone layer will be depleted, the planet will heat up, drought, famine and numerous other problems will shorten the period of human existence on the planet. Oil and coal are present in few regions of the planet, causing countries to fight wars over possession of these resources. Right now we have to turn to nature for answers, as it can contain complex answers in the most trivial places. The sun led to our existence and may well sustain our existence in the future.

Roads provide connectivity to different parts of the world and cover a large area of ​​a land mass (even over water, like bridges). When there are no cars passing by them, they sit there, gathering dust and withering. Replacing an old idea (of connectivity) with a new need (self-sustainability) is the goal of solar roads. Technology will develop over time to lessen the disadvantages and increase the advantages of solar energy. As technology improves, solar panels will become cheaper (like 3D printed solar panels) and efficiency will increase, forcing countries to turn their attention to our home star. As a long-term investment, solar roads will help sustain society, unlike asphalt roads that rely on constant maintenance, which will essentially pay for themselves. So let's move forward to a cleaner, brighter future.

Figure 6: LED-illuminated solar path in the shade