What is Renewable Energy Technology

Renewable energy is energy that is collected from resources which are naturally replenished on a human timescale. This includes sources like sunlight, wind, rain, tides, waves, and geothermal heat. These stand in contrast to fossil fuels like coal, oil, and natural gas, which are finite and take millions of years to form. The transition to renewable energy technologies is a cornerstone of the global effort to combat climate change and build a more sustainable future.

The technologies that harness these natural resources are diverse, each with its own advantages and applications. While there are many forms of renewable energy, a few key technologies are leading the charge in the transition to a clean energy grid.

Solar Power

Solar power is the energy derived from the sun's radiation. It is the most abundant energy resource on Earth, and there are two main ways we capture it.

1. Photovoltaics (PV). This is what most people think of when they hear "solar power." Photovoltaic cells, which are combined to make solar panels, convert sunlight directly into electricity. When photons of light hit the silicon in a PV cell, they knock electrons loose, creating an electric current. Solar PV has seen a dramatic drop in cost over the past decade, making it one of the cheapest forms of new electricity generation in many parts of the world. It can be deployed at a massive "utility-scale" in solar farms or at a small scale on residential rooftops.

2. Concentrated Solar Power (CSP). Instead of converting sunlight directly to electricity, CSP systems use mirrors to concentrate sunlight onto a small area. This concentrated light generates a huge amount of heat, which is used to boil water and create steam. The steam then drives a traditional turbine to generate electricity. CSP plants can often store the thermal energy, allowing them to generate electricity even after the sun has set.

Wind Power

Wind power works by converting the kinetic energy of the wind into mechanical energy. This is done using wind turbines, which are the modern descendants of traditional windmills.

A wind turbine has large blades that are designed like an airplane wing. When the wind blows, it creates a difference in pressure on either side of the blade, causing it to spin. The spinning blades turn a central shaft, which is connected to a gearbox. The gearbox increases the rotational speed and drives a generator, which produces electricity.

Wind turbines are grouped together in "wind farms," which can be located on land (onshore) or out at sea (offshore). Offshore wind farms are typically more expensive to build, but they benefit from stronger and more consistent winds, allowing them to generate more power.

Hydropower

Hydropower is one of the oldest and most established forms of renewable energy. It harnesses the energy of moving water to generate electricity. The most common form of hydropower is a dam.

A dam is built across a river to create a reservoir. Water from the reservoir is allowed to flow through tunnels in the dam, and the force of the moving water spins a turbine. The turbine is connected to a generator, which produces electricity. Hydropower is a very reliable and consistent source of power, but the construction of large dams can have significant environmental and social impacts, such as displacing communities and disrupting river ecosystems.

Other forms of hydropower include run-of-the-river systems, which divert a portion of a river's flow without the need for a large dam, and tidal power, which captures the energy of rising and falling tides.

The Challenge of Intermittency

One of the biggest challenges for solar and wind power is intermittency. The sun doesn't always shine, and the wind doesn't always blow. This variability can make it difficult to manage a power grid that relies heavily on these resources.

The key to overcoming this challenge is energy storage. Technologies that can store excess energy when the sun is shining or the wind is blowing, and then release it when it's needed, are crucial for a stable renewable energy grid. The most common form of energy storage today is batteries, particularly lithium-ion batteries, but researchers are also working on other technologies like pumped-hydro storage and compressed air storage.

A smarter, more flexible power grid is also part of the solution. A grid that can manage demand, shifting energy use to times when renewable power is abundant, can help to smooth out the intermittency of solar and wind.

The transition to a renewable energy system is a massive undertaking, but it is essential for a sustainable future. With the rapidly falling costs of solar and wind power, coupled with advancements in energy storage, the goal of a clean energy grid is becoming more achievable than ever.

Frequently Asked Questions (FAQs)

1. Is renewable energy more expensive than fossil fuels? Not anymore, in most cases. Due to massive drops in manufacturing costs over the last decade, utility-scale solar and onshore wind are now the cheapest sources of new electricity generation in a majority of countries around the world. When you factor in the environmental and health costs of fossil fuels, renewables are an even clearer winner.

2. What about the land use of solar and wind farms? While large solar and wind farms do take up a significant amount of land, their footprint can often be managed. Wind turbines, for example, have a small physical footprint, and the land between them can still be used for agriculture. Solar panels can be installed on rooftops, over parking lots (as carports), and in desert areas that are not suitable for other uses.

3. Can renewable energy power the entire world? Theoretically, yes. The amount of energy that hits the Earth from the sun in a single hour is more than the entire world consumes in a year. The challenge is not in the amount of available energy, but in our ability to capture, store, and distribute it efficiently and affordably. A combination of different renewable technologies, along with significant investments in energy storage and grid modernization, will be required to get there.