Why renewable energies aren’t that sustainable 6


Four renewables: wind, biomass, hydro and solar PV.Even if I am an advocate of an increased use of renewable energy sources I am fully aware of their drawbacks. To me, they don’t constitute the panacea most people claim they are.

After my posts on why renewables aren’t perfect solutions and the climate change mitigation paradox I would like to share with you an article from the New Scientist that caught my attention.

Indeed renewables are based on non-renewable resources. Some of them – namely biofuels – compete with food when they use crops. New and improved technologies are now being sought.

Here goes the article:

Renewable energy needs to become a lot more renewable – a theme that emerged at the Financial Times Energy Conference in London this week.

Although scientists are agreed that we must cut carbon emissions from transport and electricity generation to prevent the globe’s climate becoming hotter, and more unpredictable, the most advanced “renewable” technologies are too often based upon non-renewable resources, attendees heard.

Supratik Guha of IBM told the conference that sales of silicon solar cells are booming, with 2008 being the first year that the silicon wafers for solar cells outstripped those used for microelectronic devices.

But although silicon is the most abundant element in the Earth’s crust after oxygen, it makes relatively inefficient cells that struggle to compete with electricity generated from fossil fuels. And the most advanced solar-cell technologies rely on much rarer materials than silicon.

Rare metal

The efficiency of solar cells is measured as a percentage of light energy they convert to electricity. Silicon solar cells finally reached 25% in late December. But multi-junction solar cells can achieve efficiencies greater than 40%.

Although touted as the future of solar power, those and most other multiple-junction cells owe their performance to the rare metal indium, which is far from abundant. There are fewer than 10 indium-containing minerals, and none present in significant deposits – in total the metal accounts for a paltry 0.25 parts per million of the Earth’s crust.

Most of the rare and expensive element is used to manufacture LCD screens, an industry that has driven indium prices to $1000 per kilogram in recent years. Estimates that did not factor in an explosion in indium-containing solar panels reckon we have only a 10 year supply of it left.

If power from the Sun is to become a major source of electricity, solar panels would have to cover huge areas, making an alternative to indium essential.

Precious platinum

The dream of the hydrogen economy faces similar challenges, said Paul Adcock of UK firm Intelligent Energy.

A cheap way to generate hydrogen has so far proved elusive. New approaches, such as using bacterial enzymes to “split” water, have a long way to go before they are commercially viable.

So far, fuel cells are still the most effective way to turn the gas into electricity. But these mostly rely on expensive platinum to catalyse the reaction.

The trouble is, platinum makes indium appear super-abundant. It is present in the Earth’s crust at just 0.003 parts per billion and is priced in $ per gram, not per kilogram. Estimates say that, if the 500 million vehicles in use today were fitted with fuel cells, all the world’s platinum would be exhausted within 15 years.

Unfortunately platinum-free fuel cells are still a long way from the test track. A nickel-catalysed fuel cell developed at Wuhan University, China, has a maximum output only around 10% of that a platinum catalyst can offer.

A new approach announced yesterday demonstrates that carbon nanotubes could be more effective, as well as cheaper, than platinum. But again it will be many years before platinum-free fuel cells become a commercial prospect.

Fuel vs food?

Biofuels, like ethanol fermented from maize, are the most infamous examples of the doubtful sustainability of supposedly renewable forms of energy. This time the non-renewable resource at risk is the world’s arable land, Ausilio Bauen of Imperial College London said at the meeting.

Again, there are potential solutions, but none that are ready for market. Biofuels from cellulose or even lignin can be derived from inedible plant material and wood rather than food crops. Algae, grown in outdoor tanks, continues to attract attention, and extracting biofuel from marine algae or seaweed could sidestep land use issues altogether.

Renewable energy technologies remain the great hope for the future, and are guaranteed research funds in the short term. But unless a second generation of sustainable energy ideas based on truly sustainable resources is established, the renewable light could be in danger of dimming.

All this brings us back to conclusions that I outlined several times previously: energy efficiency is the panacea to our energy and climate problems. It is also the cheapest solution to both our energy and climate problems. Finally, one can note that its potential is  absolutely huge.

Further reading on the New Scientist : Top 7 alternative energies listed


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6 thoughts on “Why renewable energies aren’t that sustainable

  • Kiashu

    Regarding indium, what you have to remember is that before the last few years, there were very few industrial applications for it. So mining geologists just didn’t go looking for ores containing it. At $1,000/kg it’s a different matter.

    The second thing is that relatively small amounts of it are needed for solar cells. It doesn’t matter if there isn’t a lot if you don’t need a lot.

    The third thing is that it’s entirely recyclable. Unlike fossil fuels which once burned are gone forever, a metal alloyed with another can be melted down and reused. For example, in Australia 85% of the lead in lead-acid batteries is recycled into new batteries. The remaining 15% isn’t because we can’t separate it, but is the fraction of batteries which people just chuck in the bin rather than waiting for the annual “hard rubbish” collection.

    The last thing about indium is that you don’t have to make photovoltaic cells with it; it’s just that the most efficient ones (about 19% conversion of sunlight to electricity, compared to 10-15% in most solar cells) have indium. So for every 100 units of indium cells you could have 150-200 units of non-indium cells for the same output of electricity. Which is a hassle but we’re no longer talking about resource limits then, as we would be with indium.

    Hydrogen, with or without platinium, is just nonsense, it’s impractical and will never happen – that was one of the first blog articles I wrote.

    Biofuels have been generally discredited these days, those the US and EU governments are still quite keen on them, carrying on their tradition of having other countries ruin their environment for US/EU benefit (see the Niger Delta, Congo’s coltan mines, etc), and their tradition of subsidising their farmers.

    In principle biofuels can be entirely renewable, but in practice probably not. It’s like logging in that respect – we could just take what grows each year and no more, but we’re always tempted to kill and cut open the goose laying the golden eggs.

    Biofuels are bad for climate change, and even ignoring that, we could never get very much fuel from them anyway. Basically what it comes down to is: grain staples, meat or biofuels – choose any two.

    The New Scientist article ignores other renewable options which I describe here: geothermal, hydroelectric, solar thermal, tidal and wind. Nuclear is not renewable since it depends on a depleting resource, and ocean power has not been commercially-proven.

    Between geothermal, hydroelectric, solar PV, solar thermal, tidal and wind, each region ought to be able to find an appropriate balance, even accounting for the rarity of some particular element which would make one of the sources super-efficient.

    As for “renewables are based on non-renewable resources“, it’s true. Currently, the extraction of the minerals, their refinement, the manufacture of the renewable machinery, the building of the machine, the concrete it’s resting on, its maintenance and so on all involve burning fossil fuels.

    However, carbon we can treat like money – it can be well spent, or badly spent. For example, we can spend 1t of CO2 to get 6,400 to 77,000 kWh from wind, or 960-1,320 kWh from coal. Which is better value for my carbon currency spending?

    It is important to remember that there’s no such thing as “zero carbon”, only “low carbon” or “high carbon.” I was recently pointing that out to a TOD writer who called hydroelectric “carbon free” – and he should have known better. There’s no zero carbon energy sources on Earth. We can’t be zero carbob. But we can be a lot bloody lower carbon than we are now!

  • Edouard Post author

    Absolutely right on the last thing Kiashu.

    There are low carbon solutions and there are the fossil fuels one. I got an article on that very topic with a loot of research. Will finish it one of these days. So stay tuned 🙂

  • Lennon

    This article proves what I have been saying all along. It is going to be a lot more expensive than people think to get away from fossil fuels. Everything is finite, or has long term effects on something else