Given the imminent threat of climate change due to excessive consumption of fossil fuels, the need to have fully renewable electric grids has acquired critical urgency. To achieve this, we need to run everything on electricity – vehicles, trains, buildings, industrial applications, and so on. But is the transition to a post-fossil-fuel future really feasible, though the need to address climate change is urgent? Let’s take a close look at various issues involved in meeting the needs of the world through electricity made with renewable sources:
Sources of renewable energy
Renewable energy has diverse sources. Among them, solar power can be used directly for heating and producing electricity or indirectly by way of biomass, wind, ocean thermal, and hydroelectric power. Electricity is also generated from energy obtained from tides, the oceans, and hot hydrogen fusion. While energy from the gravitational field can be harnessed by tidal power, the internal heat of the Earth can be tapped geothermally.
Hydroelectric: This form uses the gravitational potential of elevated water lifted from the oceans by sunlight. It uses any extra energy in the grid to pump water uphill, and when energy is required, the water runs back down to generate power in a turbine. Storing energy for many hours or days through pumped hydroelectric storage is quite economical. However, hydropower can alter local ecosystems, so it has some environmental cost too.
Wind: Wind energy can be used to pump water or generate electricity, though it requires extensive areal coverage to produce significant amounts of energy. The movement of the atmosphere is driven by differences of temperature at the Earth’s surface when lit by sunlight. Wind and hydroelectric power are generated as a fallout of differential heating of the Earth’s surface, which results in the air moving about (wind) and precipitation forming as the air is lifted.
Solar photovoltaics: Solar energy is the direct conversion of sunlight using panels or collectors. This energy can be collected and converted in different ways. Beginning with solar water heating with solar collectors or attic cooling with solar attic fans for domestic use, this energy is utilised in complex technologies of direct conversion of sunlight to electrical energy with the help of mirrors and boilers or photovoltaic cells.
Geothermal: Energy left over from the original accretion of the planet and augmented by heat from radioactive decay seeps out slowly as an everyday phenomenon. The geothermal gradient (increase in temperature with depth) is capable of generating electricity in certain areas. Due to heat storage in the Earth’s surface, soil everywhere tends to stay at a relatively constant temperature throughout the year and can be used with pumps to heat a building during winter and cool it when it’s the summer season. Geothermal energy can lessen the need for other power to maintain suitable temperatures in buildings.
Burning biomass (plant matter): Biomass, the term for energy from plants, is, in fact, stored sunlight contained in plants. However, the burning of trees for cooking and warmth emits great amounts of carbon dioxide gases into the air and is a major contributor to unhealthy air in many areas.
However, biomass emissions are reversible and are carbon-preferable to fossil-fuel emissions. Sustainability can be achieved with effective management of biomass fields and forests.
Hydrogen and fuel cells. In a vehicle, hydrogen can be burned as a fuel with only water as the combustion product. This clean-burning fuel can lead to a significant mitigation of pollution in cities. Hydrogen can also be used in fuel cells, which are similar to batteries, to power an electric motor. As it involves the production of initial hydrogen gas, it results in relocation of pollution from the cities to the power plants. There are several promising methods to produce hydrogen, such as solar power that has no adverse impact upon the environment
Need for a smart grid using a combination of renewable sources
Renewable power sources (with the exception of hydroelectric) have low environmental costs and together have the potential to avert a potential crunch of fossil fuel significantly. These energy sources, often non-centralized, lead t, renewable energy forms entail steep costs.
All said and done, a renewable electricity grid with associated electrification may or may not reduce energy costs. But avoiding the worst effects of climate change necessitates discouraging the use of fossil fuels.
Gradually, fully renewable electric grids are becoming feasible in the world. US scholar David Timmons and his colleagues recently completed a small-scale study on the island-nation of Mauritius. The study found renewable electricity costs to be similar to present costs there, based on current capital costs for renewable energy. Other studies, too, have found costs for future renewable electricity to be lower than present fossil-fuel costs, when the volume of renewable energy systems increases, leading to better efficiency in operating them. As an instance of reducing cost, large-scale solar farms, more than 1,000 times larger than residential rooftop systems, are about half the cost. Building large-scale renewable energy projects, such as a 550-megawatt solar plant in the Mojave Desert in California, means lower costs for energy produced.
As solar and wind conditions vary across the landscape, system costs fall as their production area grows. More electricity is needed for sectors like transportation that currently rely on fossil fuels. What is needed is a robust electric grid to move electricity from places where there is supply to places of demand.
Running an electric grid with variable renewable energy reduces cost compared to always storing surplus energy. However, one cannot entirely do away with the need for energy storage. But as the grid expands, storage may be located at a distance from users. In fact, a combination of renewable sources and energy storage – subject to local conditions and preferences – can supply all the electricity needed at an affordable price, besides significantly reducing air pollution.
Governments need to make clear policies facilitating a transition to renewable energy. The consequences of climate change are borne by society rather than by energy producers – so all stakeholders need to help in making the transition. Besides leveling costs on carbon-emission, governments should focus on building the required infrastructure and mobilizing public support for opting for an all-renewable grid. The gradual transformation of the energy system will result in the creation of more employment.
Wind, solar, and geothermal resources are usually located in remote places, while the majority of the power demand comes from urban areas. In this context, we need an electric superhighway that provides infrastructure for electricity to travel from one city to another easily and efficiently. Geographical issues aside, the grid, in general, has difficulty accommodating variable sources of power like wind and solar energy, the fastest-growing sources of renewable power on the grid. Also, solar and wind are complementary if the sunny season is not the windy season. So, a combination of both turns out to be typically less expensive than either alone.
Connecting wind resources from a diversity of geographic locations helps to balance out fluctuations in wind power. In other words, when the wind isn’t blowing in one city, it may be blowing in other cities. There is a need to integrate such geographically diverse wind resources on a single electric superhighway to achieve a more steady supply of wind power to the nation’s power grid, making it easier for grid operators to make optimum use of this resource.
The smart grid or single electric superhighway can definitely make better use of diverse energy resources. It provides grid operators new ways to reduce power demand quickly when wind or solar power dips, and utilise more energy storage capabilities to absorb excess wind and solar power when it isn’t needed, and subsequently release the energy when the wind and solar power dips. The grid will optimally benefit from the variability in wind and solar resources, and smoothly ship the power to wherever it is needed.