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Can renewables meet public and political expectations?

By Tom Biegler - posted Friday, 20 May 2016


In 2012, in assessing how well a new carbon tax would work, I expressed reservations about renewable energy. Pricing emissions to make clean energy more competitive is a sound economic strategy. But the envisaged replacement technologies, especially renewables, were simply not up to the job. Feeble, intermittent solar and wind energy could not effectively replace fossil fuels, desirable as that may be, and these adverse characteristics of renewables are immutable.

In the intervening years public enthusiasm for solar and wind energy has not wavered. '100% renewables' is now a common mantra. Greens policy is to "ensure that energy generation is at least 90% renewable by 2030 and our energy efficiency is doubled". The ACT government says it will better its 90 per cent renewable energy target by 2020.

This enthusiasm for renewables reflects typical expectations of the Australian public. Can they be met? Should developments in energy technology and economics overturn my earlier doubts? Please note that there is no climate scepticism in my questions. Like the Ecomodernists, one can be critical of reliance on renewables while supporting strong action on carbon emissions.

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Ideology and politics are of course connected with public sentiment on energy technologies and sources, especially coal and nuclear. One sees a growing opposition to investment in the fossil fuel sector. There are campaigns against the banks that fund the sector, universities are divesting their conventional energy portfolios and there are prominent campaigns against fossil fuel exploration, mining and use.

Australia is one of the countries where nuclear power is illegal or otherwise restricted. One source says thatAustralian public opinion on nuclear energy is presently about equally divided, but Friends of the Earth reports lower support. Recently the South Australian Nuclear Fuel Cycle Royal Commission Report recommended that the South Australian government "pursue removal at the federal level of existing prohibitions on nuclear power generation to allow it to contribute to a low-carbon electricity system, if required".

Energy technology advances

There are abundant good news stories about growing renewables investment and declining costs, e.g. for solar photovoltaic (PV) and solar thermal technologies. The technologies themselves are improving incrementally. Enthusiasts claim that renewables are already cheaper than alternatives. Great! No need for subsidies or carbon pricing! Since not a single national climate policy is based on this premise, it seems safe to bet that the enthusiasm is premature.

Domestic rooftop solar PV in Australia's urban areas is thriving, doubtless encouraging favorable perceptions of renewable technologies generally. But rooftop PV is a special case; it can't simply be extrapolated to larger-scale generation on dedicated sites. For example, the land and elevated mounting structures (i.e. roofs) come at zero marginal cost. Existing infrastructure facilitates access for equipment, materials and labour. Existing connection to the grid obviates the need for storage or backup to guarantee continuous power supply.

Many solar PV users claim they are self-sufficient in energy. They misunderstand the term. Australian households on average use around 25 gigajoules (GJ) of electrical energy per year. Australia's total primary energy supply averages around 660 GJ per household per year. That's the energy that goes into all the goods and services that an Australian household enjoys – food, clothing, shelter, transport, infrastructure, communications, education, health, entertainment, holidays – the list goes on. A domestic solar PV system might provide 100% of a household's electricity, but that's a mere 4% or so of the total energy sustaining that household's living standards, a far cry from '100% renewables'.

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Two low-emission technologies, geothermal (enhanced geothermal systems, EGS, a renewable), and carbon capture and storage (CCS, not a renewable), figured prominently in earlier Australian energy scenarios. Geodynamics Ltd demonstrated EGS at significant scale but the company has since diversified in the clean energy sector, away from EGS. Other EGS activity has declined. Development activity in CCS continues but full scale demonstration in power generation has not occurred and one senses a decline in enthusiasm at government level. However, globally there are many active projects (plus several that are cancelled or inactive).

In my view both of these technologies face immense hurdles. EGS requires costly large-diameter wells several kilometres deep. Superheated brine must keep flowing for years at rates of several cubic metres/second through fractured rock strata. Fluid flow is bound to be affected by processes like mineral leaching, reprecipitation and pore blocking. The CCS process faces extreme challenges of scale, described by Trainer as "effectively having to construct plant capable of processing, transporting and burying more than three times the weight of all the coal, gas and oil produced each year".

Overall, I don't believe that developments in solar or wind technology have changed their intrinsic limitations or the prospects of '100% renewables'. The Australian 2010 report Zero Carbon Australia 2020 Stationary Energy Planwas a 10-year roadmap for 100% renewables; in 2014, almost the halfway mark, wind and solar accounted for 6% of our electricity and less than 1% of total energy.

Energy storage

This is a field where there have been highly visible changes. Indeed, a 'revolution' in batteries has been declared, with particular reference to the Tesla Powerwall battery for home energy storage and the Tesla electric car. Both exploit the high specific energy of lithium-ion batteries. Batteries store electrical energy, and improvements in their performance and cost are seen as key to better renewables and electric vehicles.

Market success had long eluded electric vehicles, that is, until the appearance of the Tesla sports car, a 'muscle car' with an 85kWh battery and impressive performance and range. It is said to have a favorable carbon footprint but the claim is contested. Regardless, the large, heavy Tesla is hardly a prototype for environmentally benign, energy-conserving transport.

Batteries have long been used in standalone power systems but the Powerwall and competitors like the Redflow zinc-bromide flow battery have boosted expectations for applications in domestic PV systems and 'going off-grid'. The economic benefits of expensive high specific-energy lithium batteries in such systems are unclear.

There are widespread projections of falling lithium battery costs. Tesla is entering this market and building a battery 'gigafactory' in Nevada. Lithium battery production is already in the billions. It is fair, therefore, to be cautious about any further economies of scale Tesla might find.

Tesla's batteries comprise arrays of multiple small lithium 18650 cells, each slightly larger than the common AA battery. An 85kWh Tesla battery contains over 7,000 such cells. Development of larger individual cells is desirable but so far seems to have eluded success.

Tesla's products have certainly generated market appeal but it's hard to avoid the conclusion that the much-touted battery revolution is an example of marketing hype, not reflected in more sober approaches to the latest developments in battery science.

Decoupling energy and economic growth

I previously looked at the potential for saving energy through the major gains in efficiency and productivity that feature in Australia's energy policies. Energy could be saved without damaging prosperity if energy usage and economic growth could be 'decoupled'. However the observed quantitative link between energy and economic output threw doubt on the prospects of such decoupling.

Energy productivity, EP, is the ratio of GDP to energy usage. Can it really be increased by policy measures?

Economists agree that EP depends inter alia on an economy's geography (size, climate, population distribution, etc.), development stage, industry sector structure, and levels of efficiency in energy conversion and usage. Quantifying each influence seems problematic. Energy efficiency and energy productivity are often confused. There is no clear guidance on how an economy should actually go about raising EP.

Nevertheless the profile of EP has risen dramatically. An organisation has been formed specifically to see Australia's EP doubled. A conference devoted to EP was held in Sydney in 2016, even receiving coverage in the daily press. The Minister for Resources and Energy launched the Australian National Energy Productivity Plan in December 2015, with a target increase of 40% by 2030, or 2.3% per annum. The Australian Government had previously (2010) presented a report on energy efficiency that aimed to double the EP improvement rate to 3.6% and raise EP by 30% by 2020.

The actual growth rate of Australia's EP over the past decade has been around 1.8% per annum.

In 2013 Australia's EP was $166/gigajoule (GJ), ranking it 11th in the 34 OECD economies, 9% below the OECD average and 9% above the world average. A 40% increase would have taken Australia to $232/GJ, between Austria and Spain but 27% short of the 2013 leader, Ireland ($316/GJ). These EP figures come from International Energy Agency data for total primary energy supply and GDP in constant US dollars, 2005, purchasing power parity.

What do all these numbers tell us about the current 40% EP target? Frankly I doubt whether anyone knows. A recent rigorous economic analysis of 99 countries over 40 years showed no general decoupling and cautioned against policies aiming to reduce energy intensity (reciprocal of EP) faster than historical norms. Similarly, a recent critical review examined 17 scenarios for 'deep decarbonisation' in the energy sector (e.g. 80% reduction of emissions by 2050) andconcluded that all the scenarios rested on historically unprecedented rates of EP improvement.

For reasons that are unclear, EP growth and associated energy demand reduction seem to attract a unique degree of optimism. A sensible policy stance would be to accept the likelihood of future diminishing returns instead of indefinite EP growth, and account for the observation that EP improves at around the same rate regardless of government policies.

Energy productivity cannot be raised by proclamation.

Energy Return on Investment

The concept of Energy Return on Investment, also called Energy Returned on Energy Invested, originated in the 1970s in the biological discipline of ecology (specifically, migrating fish). It was largely forgotten for three decades, but returned to prominence with rising interest in 'peak oil'.

EROI is the ratio of the energy gained from an energy-obtaining effort to the energy expended in that effort, i.e. energy out : energy in. If it is greater than unity then the effort is, or might be, worthwhile. If it's less than unity the effort is usually pointless.

The idea is simple and important but the analysis needed to account for every component is complex. Results differ and are contentious. To make things worse there is no agreement on the significance of EROI values. Unity is obviously the barest minimum; five has been suggested as the lowest value to make an energy source sustainable. Oil has an EROI as high as 30 but it has been declining to its present 10-20. This is the expected pattern for all earth resources as grades decline and discovery and extraction require more effort.

With renewable energy systems, and especially biofuels, the EROI can be much lower. A recent dramatically low result of 0.83 for solar PV has attracted much debate but is consistent with the commonplace observation that no renewable energy system has been manufactured using only renewable energy. Inclusion of storage or backup for intermittent renewables will likely have the effect of lowering EROI further.

EROI studies do prompt caution about the future role of renewables. I feel confident that, once differences in EROI methodology and results have been resolved, they will eventually provide the objective evidence-based data needed for sound energy policy.

Let me leave the last word to eminent physicist, the late Sir David MacKay FRS, renowned for his advocacy of "numbers, not adjectives" in his book Sustainable Energy – without the hot air. In hislast interview he said that the ideathat renewable energy can power the UK is an "appalling delusion".

The odds are that Australians who expect 100% renewables will be disappointed.

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About the Author

Dr Tom Biegler was a research electrochemist before becoming Chief of CSIRO Division of Mineral Chemistry. He is a Fellow of the Australian Academy of Technology and Engineering.

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