As the world races towards energy transition, abandoning fossil fuels left, right and centre, we take a look at some of the key renewables technologies and whether or not they are really sustainable.
This is not about naming and shaming, as clearly an inclusive energy mix is desirable and renewables, as well as nuclear energy offer much cleaner options than their dirtier generation counterparts.
However, it is vital that in our haste to next zero, we don’t forget to keep a check on all aspects of the renewables value chain, minimising environmental and human impacts as much as possible.
How sustainable is solar power?
Solar panels have revolutionised the energy sector, providing massive decarbonisation gains across the board. However, there is more to solar than simply erecting the panels and waiting for the sun to shine. We have to consider where PV panels come from and what happens to these panels once their lifecycle comes to an end.
According to renewableenergyhub.com, in order to make a solar panel, several elements are required, such as Silver, Copper, Nickle, Amorphous silicon, Cadmium telluride and Copper indium gallium selenideone. These minerals need to be extracted and chemically separated, processes that lead to emissions.
Polysilicon is a semiconducting material used in the production of solar panels. It’s refined from quartzite, a dense rock created when sandstone is crushed between tectonic plates. The material is baked in giant ovens and treated with chemicals until it condenses into ingots of near-pure polysilicon. Those ingots are sliced into wafers using diamond-edged saws, and then cut into squares to make solar cells that transform sunlight into electricity.
Polysilicon can become a problem as many countries lack regulatory controls concerning the dumping of waste silicon tetrachloride, a by-product of polysilicon processing. Normally the waste silicon tetrachloride is recycled but this adds to the cost of manufacture.
And what happens when a solar panel dies? According to Wired, by 2050, the International Renewable Energy Agency projects that up to 78 million metric tons of solar panels will have reached the end of their life, and that the world will be generating about 6 million metric tons of new solar e-waste annually. Proper recycling procedures are needed to ensure the valuable elements are extracted and the toxic elements, like lead, don’t leak out in landfills.
The fact is that few countries have effectively mandated these recycling measures. In the EU, the Waste from Electrical and Electronic Equipment (WEEE) law mandates proper measures however, many wealthier countries ship their e-waste to developing nations for re-use.
And it’s not just about recycling and reducing emissions…In terms of the impact on wildlife, increased numbers of bird deaths have been associated with solar farms. Utility-scale solar farms around the US may kill nearly 140,000 birds annually, possibly the result of the glare generated by the panels.
Clearly, solar power has a lot to offer the energy industry in the future however, it is clear that governments and industry need to collaborate on sustainability strategies around the deployment and decommissioning of PV.
How sustainable is wind energy?
The benefits of wind power are salient to say the least. Besides providing a reliable source of power, community investment schemes can benefit the public, larger turbines are seen as maximising land use on areas such as farms and employment opportunities are rife in the sector, with 3.3 million jobs expected over the next five years (according to GWEC). One of the most important features of wind energy, of course, is the emissions free power it produces, vital in today’s emissions sensitive climate.
However, as with solar power, there are some disadvantages to this renewable energy source.
In order to maximise the turbine’s ability to access the wind, they need to be higher than the nearest surrounding structures. This can have a negative impact on the environmental aesthetic, interrupting landscape views valued by the community. Dwellings within 130 degrees either side of north relative to a turbine can be affected by shadow flickering and noise can be intrusive in quieter, rural areas.
Building and erecting wind turbines requires hundreds of tons of materials — steel, concrete, fiberglass, copper, as well as neodymium and dysprosium used in permanent magnets, resulting in a carbon footprint yet to be fully understood.
However, one of the more salient concerns around wind turbines is the impact on local fauna. Here are three examples in this regard:
- According to a report published in the journal Ecology and Evolutionby a team of researchers from the Norwegian Institute for Nature Research in Trondheim, birds and bats are indeed at risk from turbine blades in motion. The planning stage must emphasise the avoidance of habitats to minimise avian deaths.
- Regarding offshore wind farms, scientists are still studying the potential impact on marine ecosystems. comsuggests that certain species of sharks and rays that use electromagnetic fields to navigate and hunt for food; could react to electric energy leaking from offshore wind installations.
- Marine biologist and consultant Victoria Todd believes the loud sound pulses during the construction phase can affect some species for up to 12.5 miles. For up to six weeks, construction can push out marine mammals from large areas of their habitat, Todd said, although the animals return reasonably quickly once construction ceases.
It is clear that when constructing wind farms, whether on- or off-shore, the environmental impact must be accounted for and mitigated from the planning phase as far as possible.
How sustainable is nuclear?
You might be wondering why nuclear power has made its way into this feature. The fact is that nuclear is a source of clean energy and will indeed play an important role in the future decarbonisation of our planet.
Nuclear power, an emissions free energy source, needs what is considered minimal land to operate, according to the US DoE. A typical 1,000MW nuclear facility in the United States needs a little more than 1 square mile to operate. And in terms of the waste produced, due to its dense nature, all of the used nuclear fuel produced by the U.S. nuclear energy industry over the last 60 years could fit on a football field at a depth of less than 10 yards!
However, the extremely toxic nature of nuclear waste means that proper disposal methods must be employed, and if not, the outcomes could be disastrous. Unfortunately, it seems that one of the most dangerous aspects of nuclear power is the length of time it takes for governments to decide on the ultimate disposal site.
While politicians um and ah about the best patch of rock in which to bury the waste, millions of liters of radioactive liquid waste from weapons production and power generation sit in temporary storage containers. The containers age and begin leaking.
Deep geological repositories seem to be the answer, says C&EN (Chemical & Engineering News). However, while governments decide on the site for the repository, waste accumulates mainly where it’s generated—at the power plants and processing facilities. Some of it has been sitting in interim storage since the 1940s.
One example of a working deep repository is the Waste Isolation Pilot Plant, near Carslbad, New Mexico. The site is licensed to host transuranic, or TRU waste in stable formations, such as deep salt beds.
Waste vitrification is another well known disposal method, that involves blending waste materials with glass precursors, heating the mixture to above 1,000 °C to melt the components, pouring the molten glass into a storage container, and letting it cool and solidify, locking the harmful constituents in the glass matrix. “Vitrification of nuclear waste seems to be well established by now, but actually it still faces complex problems,” says Ashutosh Goel, a materials scientist at Rutgers University. The plant at Hanford in Benton County in the U.S. state of Washington, for example, calls for entombing nuclear waste in borosilicate glass and encasing the glass in stainless-steel canisters. Yet the exact formulation of the glass, or glasses, is still under investigation. It is likely, scientists suggest, that after 1000 years the steel containers surrounding the glass could begin corroding. Recent studies further suggest that the presence of water may accelerate corrosion between the steel and glass interface.
Perhaps one word that sums up the risks surrounding nuclear is ‘Fukushima’. A number of lessons were learned concerning the importance of collaboration, proper planning and public perception. However, no matter what lessons were learned, Japan has continued to announce that 1.25 million tonnes of potentially contaminated wastewater from the decaying Fukushima nuclear power plant will be pumped into the ocean.
How sustainable is biomass?
Opposite of nuclear on the power generation spectrum is Biomass. This benign, environmentally friendly, and reliable source of renewable energy can effectively reduce waste and emissions. It seems like a winning recipe of feedstocks. However, collecting, transporting and storing that waste has its own carbon footprint and biomass for large-scale energy production requires a great deal of land.
Besides that, unsustainable biomass practices can result in deforestation over time, as some companies clear forests to create feedstock for biomass power production. According to energysage.com, “clearing plants and organic material from the earth can also impact the health of surrounding soil that requires biomass for compost and fertilization”. These practices, in turn, negatively impact or deplete natural habitats for animals and birds.
Companies that grow crops for the sole purpose of biomass can also pack an environmental punch. The water and irrigation needed can upset water balances causing drought in other areas. This has led to the need for a balance to be achieved between growing crops for energy and crops for food.
But what about emissions? The process can release pollutants into the air, such as carbon dioxide, nitrogen oxides and volatile organic compounds. Not only could this cause an unwanted smell, coupled with the smell of the feedstock (depending on the waste product being used) but could also result in the presence of pests and bacteria.
How sustainable is tidal power?
When it comes to the environmental impact of tidal power, not much is actually known. The manipulation of this potent force of nature for the production of energy is still in its infancy, and although some studies have been conducted, scientists are only now starting to scratch the surface.
What we do know for sure, however, is that the scientific community is looking closely at two main causes of concern: noise and vibration, and the impact on sea life. A good example is the 2010 report commissioned by the US National Oceanic and Atmospheric Association and titled Environmental Effects of Tidal Energy Development, which identifies several environmental effects. These include the “alteration of currents and waves”, the “emission of electro-magnetic fields” (EMFs) and its effects on marine life, as well as the “toxicity of paints, lubricants and anti-fouling coatings” used in the manufacturing of equipment. Unfortunately, this is but one report, when a lot more research needs to be done in order to properly understand the full impact. And it seems that only time will tell what impact the development of these projects will have on marine ecosystems.
How sustainable is Hydrogen?
Many people are getting tired of the ‘H’ word however, it is undeniable that green hydrogen holds great potential in supporting the planet’s decarbonisation.
But what exactly is the carbon footprint associated with hydrogen production? The answer to that is determined by the fuel used to produce the hydrogen.
Until clean hydrogen can be scaled up, producing hydrogen remains heavily dependent on fossil fuels. Currently, there are three main sources of hydrogen:
- Natural gas – When the methane in natural gas is heated, the molecules split into carbon monoxide and hydrogen. The carbon monoxide can then be treated to produce water gas, from which hydrogen can be extracted.
- Oil – can either go through the same process as natural gas or, if it’s heavy fuel oil, can be turned into hydrogen via partial oxidation. This involves using high pressures and temperatures to oxidate the oil which, in turn, produces a synthesis gas partially made of hydrogen.
- Coal –can also be turned into gas, and during the process its molecules are broken down into their hydrogen and carbon monoxide parts.
If the emissions used to create hydrogen are trapped and stored underground (a process called carbon capture and storage, or CCS), the fuel is called blue hydrogen, a cleaner option than coal gasification or steam methane reforming.
However, in order for hydrogen to be the poster child of the clean energy revolution, only green hydrogen, achieved by electrolysis will do. Electrolysis uses electricity to split the hydrogen from water and if this is powered by renewable energy, it has zero emissions and is known as green hydrogen.
The production of hydrogen today is a “climate killer” according to Carlo Zorzoli of Enel Green Power. He said some “98% of it is produced from steam reforming and gasification, which equates to yearly carbon emissions comparable to that of Indonesia and the UK combined. Just 2% is produced from electrolysis.”
“Today, hydrogen is anything but clean. That 98% produced today is an industrial feedstock. Just 2% is produced from electrolysis. Hydrogen today is not a solution to decarbonisation: hydrogen is a part of the problem. So the very first thing to do is convert grey hydrogen to green.”
This statement clearly shows there is work to be done in order to ensure hydrogen can have the decarbonising effect the sector is hoping for.
The fact is that no matter how flat the pancake, it will always have two sides. Therefore, let us not forget that as we innovate and adopt new renewable and clean energy technologies, there could be hidden impacts on the environment and on us, now and for generations to come. The good news is that industry and governments around the world are becoming more aware of sustainability, prioritizing it in strategic plans, as well as reducing carbon footprints across the value chain. The future is indeed bright, almost as bright as a few hundred solar panels reflecting sunshine into your eyes.
Originally published by Power Engineering International.