Wishes Vs Reality: The Role Of Net Energy Analysis In Our Future

The Good

There are encouraging signs that the world is finally waking up to the climate challenge. One of the most encouraging signs is the growing acknowledgement that we need to transition away from greenhouse gas-emitting fossil fuels. Plans to do so inevitably turn to various renewable energy sources to replace oil, coal and gas. In NZ, hydro, solar, wind, geothermal, biomass and hydrogen are being promoted as replacement fuels to keep our society going.

Various proposals have been made by government bodies and political parties, as well as power authorities, to increase the use of renewable energy sources over the coming decades. There is a growing recognition of the urgency to transition away from fossil fuels to avert an irreversible climate crisis, and increasingly, renewables are seen as the solution.

Renewable energy sources have many advantages over fossil fuels. They produce much less greenhouse gas emissions to operate, they are generally less expensive to both produce and operate, and they avoid dangerous air and noise pollution. Many advances have improved the reliability and efficiencies of various renewable energy technologies and more improvements are being researched. Significant government and private funding is going into the expansion of renewable energy systems in NZ and elsewhere.

An additional attraction of renewables to many analysts and policy makers is that they are said to allow us to basically continue living as we have been, but with a different energy source. Is this wish to keep going as we have been with renewables realistic?

The Bad – A Reality Check

It is clear that reducing greenhouse gas emissions is an absolute necessity if we are to avert serious climate risks. But have analysts and policy makers really considered the broad implications of a transition to a mostly renewable energy system? Let’s explore some of the issues various research groups have flagged which seriously challenge these wishful assumptions.

Magnitude of the Task.

NZ is fortunate in already having a relatively large percentage of our total energy use from renewable sources, largely hydroelectric and biomass. This still leaves an unprecedented large scale switch to a new energy system over a relatively short time – a couple of decades to avert climate disaster. The task of building enough renewable energy infrastructure to replace fossil fuels is, ironically, going to require fossil fuels, emitting more greenhouse gases at a time when we are struggling to reduce them. Using renewable energy to produce more renewable energy infrastructure on the scale required is simply not possible.

Material Availability.

Creating a new energy infrastructure will require significant materials, including some rare earth materials. Some researchers have questioned whether sufficient reserves are available. In some cases, the needed renewables would require many times known reserves; in other cases the needed renewables would use such a large proportion of reserves that these materials would not be available for other important uses, curtailing economic activity in these related areas.

Net Energy Analysis.

This is the elephant in the room. With the exception of hydroelectric energy, all other known renewable energy sources have a lower net energy surplus than the fossil fuels we have been using for the last 100 plus years. Net energy surplus is the energy available to society to do things other than produce more energy. It is calculated by subtracting the energy required to produce energy from the total produced.

Most analysts only consider total energy supply, rather than net energy. This is understandable from a historical perspective because when fossil fuels began to replace wood over 100 years ago, there was very little difference between the total energy produced, and the available net or surplus actually available to society. Relatively little energy was needed to extract the petroleum from conventional oil wells, for example, so the surplus was large and easily available to do work in society.

Over the ensuing decades the net energy from all fossil fuels has declined significantly, roughly 80%. The easily extracted resources were used up first, and producers turned to ever more difficult to extract fossil fuels from deep under the ocean, from tar sands and from rock formations (shale oil and fracking). All of these unconventional oil reserves require considerably more energy to extract. This decline in net energy surplus from fossil fuels is well understood by energy engineers, but hardly acknowledged by energy analysts and policy makers.

The reduced net or surplus energy now available from fossil fuels is approaching the level provided by most renewable energy technologies.

This reality is likely to have profound implications for how we use renewable energy going forward. But because net energy analyses are largely ignored by government, financial and business analysts, these implications are rarely considered in developing clean energy alternatives.

Several research groups have concluded that because of these changes in net energy, a mostly renewable energy system as advocated by various green growth models may not be up to the task of fuelling our complex industrial society as it now exists.

This conclusion is radically different from the common assumption that simply changing energy sources will allow us to continue along the trajectory we are already on. Many of these research groups point out the biophysical necessity of learning to live with less energy over the next few decades. This almost unthinkable conclusion has been largely ignored by analysts and policy makers.

This series on the Energy Transition will explore these different views of our energy future, their implications and significance for NZ, and the options available to us.

The Dig and the Better Futures Forum are running this Transitional Energy Series in order to address what we see as the major questions New Zealand faces surrounding energy if we are to make this transition.

Help us answer some of these questions here

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