Currently, 85% of the worlds energy is provided by fossil fuels. The problem, however, is that these resources are constantly being depleted with no methods to replace them. If these energy sources continue to be used at their current rates, we will have exhausted all known reservoirs of oil by 2062, coal by 2134, and natural gas by 2074. Additionally, energy production from fossil fuels create harmful by-products, or emissions, which affect the environment and may be a leading contributor to climate change. Renewable energy, however, is replenished naturally and have minimal impact on the environment, hence the term ‘green energy’.
Within the past decade there has been an increased focus of intent in implementing alternative and renewable energies over the traditional use of fossil fuels. The research and development into biofuels, hydrogen, solar, wind and geothermal energies has shown promise in relieving the stresses on the planet from the use of fossil fuels, and that, one day, the world may generate its power from 100% renewable sources. Recently, the Energy Information Administration issued its 2015 Annual Energy Outlook and highlighted an increase in renewable energy expected in coming years.
While technologies for renewable energies continue to develop at a rapid rate, there are still obstacles to be overcome before they fully replace oil, coal, and natural gas as primary sources of energy. The question then becomes, “What will it take to overcome those obstacles?”
The main obstacles in the way of transitioning from fossil fuels to renewable energies are cost and storage. It is estimated that for the United States alone, it would take nearly $15 trillion in capital investments to effect the transition to renewables, but once in effect, energy costs would be comparable, if not less, than current costs. Outside of cost, renewable energies are not always consistent; the sun doesn’t always shine and the wind doesn’t always blow. Therefore, the need for a multitude of large scale generator facilities (solar panel and wind turbine ‘fields’) is likely to harness sufficient amounts of energy to supply our energy needs. It’s one feat of engineering to develop and install the systems required to harness the benefits of renewable energy, but another key challenge is developing a means to store all of the extra energy. Although there are storage solutions, they are costly and it is difficult to transfer the energy. For renewables, effective energy storage is the crux of the renewable energy movement. It is the biggest hurdle in making intermittent forms of renewable electricity generation effective.
As an example, the average solar panel on the roof of your home is capable of generating 200 watts of power, but not all of that can be stored in a home battery. The efficiency of the battery is about 60 to 70%, so 30 to 40% of the energy is wasted. Ultimately, the loss in the transfer of energy prevents solar power from being fully efficient, whereas fossil fuels can be stored and utilized at any time with minimal loss of energy.
The density of energy is also an important characteristic in the efficiency of an energy source. The measurement of the density of an energy source is calculated in MegaJoules per Kilogram (MJ/Kg). As a reference, 1 MJ is about equal to 0.28 KiloWatt hours (kWh), and 1 kWh will power a 40 Watt lightbulb for 25 hours. An energy density chart shows various forms of energy and their relative energy density. Fossil fuels are the densest form of energy and the most efficient.
Despite the obstacles that renewable energy technologies must overcome, the interest in renewable energy will continue to grow as the resources for fossil fuels dwindles. Unlike fossil fuels, renewable energy is sustainable and cleaner and as the technologies develop and costs reduce, renewable energy systems will be able to compete with existing energy sources. Perhaps within the next 100 years, humanity will see its global energy requirements provided primarily by renewables, and fossil fuels will go the way of the dinosaurs!