Linda and I watched the film “Planet of the Humans” a few days ago. It’s a very good film and raises some serious questions, especially around biomass energy.
However, some of its content is quite misleading, especially regarding solar photovoltaic panels and wind turbines. The film rightly pointed out that a lot of CO2 is created in producing these but it failed to state that this is totally outweighed by the much less CO2 that is generated during their operation, compared to fossil-fuel plants.
The film points out that a lot of energy, sometimes from coal, is required to produce the panels, implying that they produce more CO2 than they save. This is not true. This life-cycle article at Only Natural Energy concludes:
“As demonstrated by the scientific literature collected by … the US Department of Energy, the energy invested to produce a photovoltaic system, including components and installation, ranges from 3 to 13% of what the system will produce in 30 years.”
In Ontario, where only about 3% of our electricity comes from fossil fuels and most of the rest from nuclear and hydroelectric, the embodied carbon in solar panels could take several years to be recouped in saved energy, but the electricity has to come from somewhere so solar panels are still much better than electricity from natural gas. Read more on embodied carbon in photovotaic panels in this good article from Circular Ecology.
The story is similar for wind turbines and their carbon footprint. This article on carbon and energy payback of a wind turbine from Sask Wind concludes:
“The short answer is that a typical wind turbine, of the type shown, will have an energy payback of less than 6 months and a carbon dioxide payback of around 6 months.”
You would expect SaskWind to favour wind energy but their article is consistent with this 2017 article in the prestigious Nature journal which concluded:
“The most important finding [of our research] was that the expansion of wind and solar power … comes with life-cycle emissions that are much smaller than the remaining emissions from existing fossil power plants, before they can finally be decommissioned.”
Note also that the decommissioning of fossil fuel plants at the end of their lives will be more costly than decommissioning either wind or solar generators.
Back-up Energy Storage:
The film is correct in stating that back-up power is needed for both solar and wind, which are intermittent. In Ontario, much of this power can be supplied by nuclear and hydroelectric, but as nuclear is retired we will need energy storage systems, such as batteries, to cover the “off” period of solar and wind. The current “best choice” is lithium hydride batteries, but they are relatively short-lived and their production is quite polluting. Luckily, better batteries seem close to market.
In addition to these misleading statements about the science you might also want to read this critique of the film from Earther Gizmo, and this response from Bill McKibben to what he believes was misleading about his past connections to various corporate groups.
- Gizmodo – Planet of the Humans Comes This Close
- 350.org – Bill McKibben responds to Planet of the Humans
- SaskWind – Carbon and Energy Payback of a Wind Turbine
- Only Natural Energy – The True Carbon Footprint of Photovoltaic Energy/
- Circular Ecology – Embodied Carbon of Solar PV
- Carbon Brief – Solar Wind Nuclear Amazingly Low Carbon Footprints