We finally listened to scientists on climate change, and we listened to scientists on the pandemic. Perhaps it’s time to pay attention to the energy scientists, writes climate and sustainability expert Jack Santa Barbara.

Our energy future is clearly with renewable energy sources as we tackle climate change by moving away from fossil fuels. Renewable energy clearly has an advantage in terms of climate impacts and is being embraced by governments and businesses around the world. The technology is well established and becoming increasingly affordable – a happy situation all around.

But is it? Have decision-makers really understood the implications of a mostly or fully renewable energy system? Do we appreciate their limits as well as their benefits?

Much like the history of climate science reaching decision-makers, there are currently several groups of scientists around the world calling for attention to some key features of renewable energy generally not appreciated by either the public or decision-makers. To date, these scientists have largely been ignored in planning for a renewable energy future.

Dr Charles Hall of the College of Environmental Science and Forestry, Syracuse, NY, is one of the pioneers of research in this area. He says:

“We are amazed that there are no government, private, or nongovernmental organisation programs or entities dedicated to attempting to understand and calculate EROI and its effects as well and as objectively as possible given that it may be the largest determinant of many aspects of our future.” 

So what is EROI and why is it said to be so important to our future? EROI (sometimes written as EROEI) stands for Energy Return on (Energy) Invested. It is a measure of the net or surplus energy available from the total energy produced. It is analogous to net pay, after various deductions – what you actually get to spend. Net energy is the energy available to actually do work in society, other than produce more energy.

Scientists are calling attention to this measure because they are coming to the conclusion that we are going to have to learn to live with less net or surplus energy as we move to renewable sources.

This is not what we generally understand about renewable energy. There is more energy from the sun hitting the earth every day to provide more than we could ever use. Same for the wind. So what’s the problem?

It is true that there are large quantities of sun and wind (and other renewable energy sources) to harvest and use as electricity. But that’s the rub; we have to harvest these ubiquitous but diffuse energy sources to produce electricity. Harvesting and concentrating these diffuse sources of energy require quite a bit of technology to turn them into electricity. Producing these technologies requires energy inputs, and the amount of inputs relative to the outputs is very different from what we experienced with fossil fuels over the last 150 years.

For example, the net energy return, or EROI, for conventional oil wells early in the 1900’s was an incredible 100:1. For every unit of energy needed to extract the oil, 100 units of energy were produced to use in society. It is this almost magically high net energy return that has allowed us to build our complex industrial society. Imagine your savings account providing that kind of return.

As increasingly more unconventional sources of oil in particular are mined (deep sea, arctic, tar sands, oil shale, fracking, etc), the net energy return is declining. More energy is needed to extract these unconventional sources of oil, hence the net or surplus energy available is reduced. The same decline in net energy is occurring for natural gas and coal, as well as for oil.

But most important for our energy future is the net energy available from renewable energy sources. Almost all renewable energy technologies provide a lower net energy return than the traditional fossil fuels with which we built our complex industrial civilisation. Large wind turbines can provide a net energy return of up to 20:1, which is higher than that from all fossil fuels sources combined. Solar panels provide about 10:1.

A key feature of these renewable energy sources is that they are intermittent – the sun doesn’t always shine and the wind doesn’t always blow. This problem of intermittency is generally being addressed by either making the renewable energy system larger than it would otherwise need to be, or by storing the energy produced, to be used when the sun or wind are not available. Both approaches to intermittency require more material and energy inputs, which affects the net energy available from these renewable energy systems.

When planning our energy future it is important to not only consider the net energy from individual units like wind turbines or PV panels, but from the entire system with all its redundancies and storage capacities taken into account. A recent and quite sophisticated simulation of different levels of renewable energy in a system found that the net energy from a fully renewable system would be less than 5:1.

This level of net energy return is actually lower than what several scholars have concluded is necessary for maintaining a complex industrial society, which ranges from 11:1 to 7:1, depending on what features one is attempting to maintain.

So far we have been talking about global energy studies. New Zealand is in a unique position to have a large amount of hydro electric power available. Hydro power has the highest net energy return of all renewable energy sources, with the specific amount varying from site to site. In some cases it is reported to exceed 100:1.

Whatever the net energy return of New Zealand’s hydro schemes might be at source, if a system approach is to be examined we would need to include transmission of the power produced across many kilometres to where it is actually used, and we would also have to account for storage if that is to be part of the mix. The critical measure of net energy is at actual point of use, not where it is produced (the latter will always be higher).

New Zealand is quite appropriately acknowledging the need to move away from fossil fuels to ensure a safe climate. Many large energy schemes are being planned, and funded, to move to renewables. We have the proposal to use Lake Onslow for storing water to use during dry seasons; we have a major investment in hydrogen being undertaken in Taranaki; we have the potential of having the Tiwai Point hydro power station becoming available for alternative uses; and we have Transpower planning significant expansion of its infrastructure to provide for the anticipated growth of demand for electricity, including the building of natural gas plants to ensure base load capacity. Various policy proposals are made by politicians for supporting solar panels or electric vehicles. We also have a Climate Change Commission making plans for supporting various renewable energy sources to reduce fossil fuel use.

Important as these initiatives are, none of them seem to be considering the net energy implications of what is being proposed. Given the call from various research teams to address net energy analysis in planning renewable energy systems, this lack of attention to net energy could prove troublesome to our energy future. What these scientist are saying is that due to the limitations of renewable energy systems we cannot assume that demand will drive supply, as it has in the past. Recall that our collective memories only include decades of increasing energy availability. These scientists are saying that is changing and we need to pay attention.

Dr. Iñigo Capellán-Pérez, of the Group for Energy, Economics and System Dynamics of the University of Valladolid, Spain sums up one of his team’s studies thus:

“The results [of an EU-funded study] show that a significant systemic-energy scarcity risk exists: future global energy demand-driven transitions as performed in the past might be unfeasible. These critical energy constraints have the potential to provoke unexpected abrupt changes in societies … 

New Zealand’s hydro power puts us in a favourable position with respect to our energy transition, but it is still important to understand the energetic limits these scientists are flagging. There is very little research regarding net energy analyses in New Zealand, and all renewable energy systems will have specific site-determined characteristics that need to be understood and incorporated into planning the needed transition. We need to better understand just what our local resources can, and cannot, provide.

In addition, we need to consider the implications of a lower net energy future at a global level, where most nations will not have New Zealand’s unique advantages. There are major social and political implications of a lower net energy future that will affect both our supply chains and our exports, and perhaps even our immigration policies in ways we have not begun to contemplate.

We finally listened to the scientists regarding climate change, albeit with a costly delay. We listened to the scientists regarding the pandemic to our advantage. Perhaps we should also pay attention to the energy scientists imploring us to consider net energy analysis as we plan our energy future.

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