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Eco-footprints and technological change

By Dave Elliott

In their paper ‘A system of systems approach to energy sustainability assessment: are all renewables really green?’ Saeed Hadian (UCLA) and Kaveh Madani (ICL), take a comprehensive look at energy system carbon footprints, water footprints, land footprints and costs. They conclude that geothermal energy has the lowest impact, biomass elephant grass the most. As you might expect, coal and oil are also high, wind and solar thermal low, but so is nuclear, while PV solar comes out quite high – more than hydro, or gas: – cor0005

There have been several other attempts to rank energy systems on this type of basis, and the conclusions vary. In some cases substantially, as with Brook and Bradshaw’s 2014 paper ‘Key role for nuclear energy in global biodiversity conservation’:

Less controversially, a global life-cycle assessment of clean energy sources by a multi-nation team looked at resource (materials) use and eco-impacts, including land use and biodiversity, but didn’t include nuclear or biomass:

Studies which did include nuclear have usually found it to have high, sometimes the highest, impact, with the assessments often being rendered in terms of extra external costs, as with the EU EXTERNE study: A subsequent study by Ecofys for the European Commission put the total nuclear social and eco costs at €18-22/MWh, more than for any renewable:

Full life cycle eco-impact analysis, and resource efficiency and biodiversity assessments, are notoriously difficult and sensitive to often contested framing assumptions and data limitations, and there is risk of ‘confirmation bias’. So maybe we shouldn’t put too much reliance on the outcomes and certainly not just use the ones we agree with! Part of the problem is that technology is moving ahead rapidly. The development of (floating) off-shore wind, and even floating PV solar, makes early land-use and biodiversity estimates unreliable. So do new biomass conversion technologies, like high efficiency supercritical water gasification:

There are also other adjustments that need to be taken into account. For example, we now have better data on lifetime performances of wind turbines. A much mentioned report in 2012 by Prof. Gordon Hughes for REF, the Renewable Energy Foundation, suggested that the load factors of wind farms in the UK had declined by 5–13% per year, normalising for month-by-month variations in wind speeds.  If true that clearly could have significant policy implications for the desirability of investing in wind power. However a recent academic study, using actual load factors recorded monthly for the period of 2002–12, covering 1686 farm-years of operation, found that the wind turbines only lost 1.6 ± 0.2% of their output per year, with average load factors declining from 28.5% when new to 21% at age 19. This trend was consistent for different generations of turbine design and individual wind farms. This level of degradation reduces a wind farm’s output by 12% over a twenty year lifetime, increasing the levelised cost of electricity by 9%. So REF seems to have got it very wrong. There is ageing, but it’s slow:

In addition to incremental improvements, with, for example, wind load factors continually rising (to 37.7% for offshore wind in the UK – better than the 30.5% for gas-fired CCGTs), many new ideas are emerging. If you want a glimpse of the scale and pace of new technology development in the renewables field, take a look at the study by the Swiss global impact/investment strategy firm Impact Economy, Energy Transition Fast Forward! Scouting the Solutions for the 80-100% Renewable Economy. It reviews ‘disruptive innovation’ opportunities in the renewable energy industry. It certainly casts the net wide, looking at innovations across the board – including, in wind, airborne devices to get higher wind speeds, and in solar PV, what it sees as two potentially key breakthroughs: rectennas, which reach microwave range efficiencies in the infrared and optical ranges, converting sunlight to electricity, and optical (nano) antennas that keep light trapped longer in the cell than previously used microstructures. It says ‘Nanotechnology Solar, a startup based in Germany has come up with a solution of using advanced nano-imprint lithography that allows the cost effective production of gradient nanostructures for optical components. First preliminary experiments and simulation results indicate that this solution could increase the relative efficiency of solar cells by over 10% and in the future, a silicon solar cell/module with a relative efficiency of over 24% could be realized’. It even mentions the Japanese Lunar Ring Earth-beaming PV idea! But suggests a focus on Earth-bound perovskite, organic, quantum dot and plasmonic solar cells. There are also sections of energy storage and electric vehicles. And overall it offers a wide range of technologies that might speed things up:

With technology changing so fast, reliable impact assessments, as well as cost forecasts, are hard to make. We now have PV project contracts going forward at £79/MWh (in the UK) and offshore wind £75/MWh (off Denmark), confounding earlier estimates. I tried to struggle with all this in my new Palgrave Pivot e-book ‘Green Energy Futures’, mapping out the technical options ahead and their likely social and economic implications. I start with the assumption that the use of fossil fuels has to be halted, probably long before this is forced on us by the inevitable ultimate depletion of these resources.

Unsurprisingly, given the high cost, slow rate of progress and many unresolved problems, I conclude that nuclear is unlikely to have much of a role in future, and argue that the pro- and anti-nuclear debate has absorbed too much time and energy over the years, to the detriment of the arguably more relevant, interesting and increasingly urgent debate over what sort of renewable/efficiency mix we need. That is my main focus in the bulk of the book, which explores the implications of shifting to greener, cleaner energy sources -including the environmental impacts. I argue that there is no one green future. There is a range of possible options of various types and scales: we need to choose amongst them. And drawing heavily on material from Renew, the newsletter I edit, I offer an overview of the technical, social, economic and environmental issues to help, exploring what the technological mix might be, and what choices might be available:

Hopefully it will sit well alongside Walt Patterson’s new book, ‘Electricity Vs Fire: the fight for our future’, which adopts a much broader perspective: we have to rely on combustion less, use it better when we do use it, and pay more attention to what we need, rather than just rushing to use either fire or electricity. Amen to that.

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