"It took almost 80 years for oil to surpass coal as the major fuel for the global economy in the 1960's and coal is still in the mix today" By Dr Paul Deane, ERI, MaREI, School of Engineering

Opinion: despite very positive advances in renewable technology, we have a long way to go before impactful measures are seen

Wind and solar energy have seen dramatic reductions in costs and big increases in global capacity in the past five years. The idea of completely powering our world without fossil fuels and using only wind, solar and smart devices is very appealing. A symphony of wind blowing, solar shining, and batteries charging in harmony to meet our daily energy demand is conceptually logical but incredibly challenging.

Conversations on energy futures are often simplified and polarised. They're simplified because they generally only consider electricity which is one fifth of final energy and polarised as they tend to look at renewable futures rather than low carbon options. Anything short of 100 percent renewable energy is sometimes suggested to be compromised or corrupted by the influence of the fossil fuel industry.

What is often lacking is context and context is important.

Today, wind and solar energy meet about two percent of all our full global energy needs. Despite very positive advances in renewable technology, we have a long way to go before impactful measures are seen. This has to be seen in the context of rising global emissions, growing global population and rising energy consumption A number of studies have shown that, in theory, with enough wind turbines, solar panels and smart storage solutions, we could produce enough electricity at any one point in time to meet all our energy needs.

These insights are important first steps to understanding a fossil fuel free future, but do not consider important technical aspects to bridge the gap between theory and reality. It’s like assuming you can meet the water needs for your house by catching and storing the water that falls on your roof, but ignore other challenges, like water pressure, water quality and what happens in times of drought or leaks.

The large scale application is to date unproven as it is not understood if we can operate 100 percent renewable energy systems with wind and solar alone in a reliable, secure and safe way. Planning the future on unproven concepts is risky. The wider balance of evidence shows that our future energy needs are more likely to be met by with a mix of fuels and technologies including fossil fuels

Studies by the International Energy Agency and the International Renewable Energy Agency examined two visions of a low carbon future aligned with the ambitious Paris Climate Change Agreement. The studies showed that, while the world must strive to significantly reduce the use of fossil fuels, they would likely remain an important part of the global mix.

There are a number of reasons why it is difficult to completely rid ourselves of fossil fuels. There are several areas, such as petrochemicals, heavy transport, heavy industry, shipping and aviation, that are difficult or costly to electrify and may rely on oil into the foreseeable future

While electricity will play a much more important role in a cleaner future, as it can be emissions free at the point of source, our understanding on how the future electricity grid will behave without large conventional power plants is poorly understood.

Today’s power plants provide an important technical characteristic called "inertia" to the power system which acts like a glue keeping our electricity system pulsating at a regular frequency. This is important for a stable power supply. Few countries, with the exception of Ireland have any operational experience in this area

History also tells us that changing energy fuels takes time and legacy fuels often linger on. It took almost 80 years for oil to surpass coal as the major fuel for the global economy in the 1960s and coal is still in the mix today. Wind and solar must play an important part of a cleaner future. But we need to dramatically increase their deployment as they are unlikely to be able to meet the challenge alone and may have to be complimented by other fuels.

Natural gas may continue to play an important role providing system flexibility in the power sector and substitute for fuels with higher emissions for heating purposes and in transport. This means that sustainable bioenergy and low carbon options such as nuclear and fossil fuels technologies which capture or reuse carbon might fill the gap.

Good news stories on renewable progress are important, but we must not be lulled into a sense of complacency on the challenge of achieving a cleaner future. As a global community, we are failing miserably on transitioning to a cleaner economy and nothing encourages failure like complacency.