UN Study Compares Renewable Energy Emissions and Pollution

With growing urgency, governments across the globe are setting bold targets for renewable energy. However, the United Nations Environment Programme (UNEP) says that smart development will be needed to ensure the right mix of low-carbon electricity generation to cut emissions and to avoid unexpected environmental problems.

“It is crucial to determine the optimal mix of these technologies,” writes Achim Steiner, UNEP executive director, in the report Green Energy Choices: The Benefits, Risks and Trade-Offs of Low-Carbon Technologies for Electricity Production .

The November study compares the environmental, human health and resourse impacts of coal and gas with and without CO2 capture and storage and photovoltaic (PV), concentrated solar, hydro, geothermal and wind sources of power.

The report says the benefits during the life cycle of renewables are clear: their greenhouse gas (GHG) emissions are five to ten per cent of those from fossil fuels, and their environmental damage is three to 10 times lower than coal or natural gas.

However, the study points out that renewables have potential trade-offs, like increased land use, greater resource demands for construction materials and, most concerning, high demand for rare earth elements (REEs) and metals.

Weighing the trade-offs

These issues will need to be minimized as renewable generation grows.

“There is a risk that shifting the burden of curbing emissions to other parts of the economic chain may simply cause new environmental and social problems, such as heavy metal pollution, habitat destruction or resource depletion,” the study says.

Weighing the trade-offs will help countries avoid technological and infrastructural “lock-ins that will be difficult to change” as the world invests trillions of dollars to satisfy rising energy demands by 2050.

Two concerns explored by the study are the higher use of land and the amount of construction materials that renewables use compared to fossil fuels. However, the study says these problems can be managed at the planning stage.

For example, the land use impact of renewables is much lower when solar panels are installed in urban areas, and the impact of wind farms can be lessened by allowing agriculture around wind farms.

Edgar Hertwich, director of Yale’s Center for Industrial Ecology and the lead writer of the UNEP report, says that, despite renewable energy demands for iron, aluminum and copper, mining metals have a much less significant environmental impact than mining coal burned in power plants.

The study says the amount of construction materials needed to build all the renewable energy power plants required to avoid temperatures reaching two degrees Celsius, the goal from COP21, is one year of current global production of iron and two years of copper.

The devil is in the GHG details

Daniel Nugent, a prosecutor with the U.S. Federal Energy Regulatory Commission, says most people don’t think about the carbon footprint of renewable power.

“By identifying the life cycle stages of these technologies that are most responsible for emissions, we can lower their carbon footprint,” says Nugent. He adds that it is vital for countries to adopt renewables to fight climate change.

Nugent published an article in Energy Policy, “Assessing the lifecycle greenhouse gas emissions from solar PV and wind energy: A critical meta-survey,” where he examines more than 153 studies on the life cycle of CO2 emissions in wind and solar PV systems with the Vermont Law School’s Institute for Energy and the Environment.

His study found wind energy emits an average of 34.11 grams of CO2 per kilowatt-hour over its lifetime, with a range of 0.4 to 364 grams. For solar PV, the mean was 49.92 grams of CO2 per kilowatt-hour, with a range of one to 218 grams. In comparison, coal produces 938.93 grams of CO2 per kilowatt-hour, and natural gas sits at 553.38 grams of CO2 per kilowatt-hour when burned alone, according to the U.S. Energy Information Administration.

Nugent’s study accounts for CO2 from the extraction of the materials to manufacturing, transportation, construction and decommission.

“Whether the system is produced in Germany or China or Brazil can make a big difference,” Nugent says.

His study found that the energy source used to manufacture components is critical as 71 per cent of emissions happened during resource extraction and solar and wind component manufacturing. The same process in Germany, with ample nuclear and gas power, can have half the GHG emissions of the process in China, which relies on coal power.

Design also influences the CO2 emissions of renewables. For example, large wind turbines emit three times less than small turbines. As well, the lifetime emissions decrease substantially as the lifespan increases.

Down the black hole of REEs

A concern the UNEP study points out is that green technologies currently require a high use of REEs and special metals, such as neodymium, dysprosium, cadmium, tellurium, gallium, indium and selenium.

These are common materials, but they are extremely hard to find in big concentrations, which makes them economically hard to mine. The demand for these materials is growing as they are used in smart phones, electrical vehicles, sound equipment, computers and more.

Neodymium, an REE, is the main component of the magnets used to increase the reliability and generating capacity of wind turbines. A 3.5-megawatt turbine uses an average of 600 kilograms of REEs.

There is relatively little data to estimate how big the demand for these materials might become, says Thomas Gibon, one of the contributors to the UNEP report and a PhD candidate at the Norwegian University of Science and Technology.

Gibon explains that the shorter lifespan of wind and solar power plants and their intermittency mean more infrastructure will be required to satisfy energy demand, further stressing these precious resourses.

“A wind turbine may have a lifespan of 20–25 years," Gibon says, “so all the material investments you make last 20 years, and then you have to rebuild.”

The supply chain for REEs isn’t clearly identified, says Gibon. He adds that recycling could alleviate the strain, but “with the existing collection and recycling schemes we have now, recycling these materials is not really possible.”

“Unless we figure out how to recycle these materials at a large scale, this will be a problem in the future,” Gibon says. “But we don't have enough information to say how big a problem it will be. We don't have enough retiring renewable energy power plants yet to see how it will go.”

Forecasting REE demand

Alex King, director of the U.S. Department of Energy’s (DOE’s) Critical Materials Institute, says demand for REEs will go up as the world electrifies everything. He adds, though, that “this should be regarded as a concern, not a crisis...If new demand comes along, particularly for heavy REEs, we will have a scramble to fill that demand."

In 2011, the DOE projected that building all the green technology needed to stabilize CO2 emissions would increase demand for the REE dysprosium by 2,600 per cent by 2035. But the Massachusetts Institute of Technology estimates that dysprosium production will rise by only five per cent per year between 2011 and 2025.

The situation with neodymium isn’t as critical, yet it is still worrisome, adds Ryan Castilloux, founding director and market research analyst with Adamas Intelligence, an REE consultancy group with offices in Amsterdam and Subdury, Ont.

According to Castilloux, by the end of the decade, the availability of neodymium will become increasingly limited unless new sources come on stream.

“This will challenge the world’s ambitious targets for rapid uptake of renewable power sources and electrified transport,” Castilloux says.

Finding solutions to a risky and dirty supply chain

Mining REEs has great geopolitical risks. Around 90 per cent of REEs are mined in China, and in 2011 when China blocked exports to Japan, their price spiked 25 times the usual going rate, says King. In 2009, China introduced exporting quotas, which pushed world manufacturers to relocate to China. Today, more than 75 per cent of all neodymium magnets are made in China, according to the DOE.

To mitigate all the risks, King says the industry is focused in three areas: developing new mines, finding substitutes and creating recycling programs. Boulder Wind Power and the DOE are designing an offshore wind turbine dive train capable of producing three to 10 megawatts of power without dysprosium.

King bets that the use of REEs with decrease and the existing supply will be increasingly recycled to deal with the supply chain issue. This is because opening a mine with separation and processing facilities may cost $1 billion to serve a $2 billion to $3 billion market, according to the DOE.

China produces REEs as byproduct of iron mining. During the 2010 price spike, more than 400 mine sites were identified worldwide, and if demand rises, some of those mines could be developed.

However, sustainable mining can be costly, says King. “We are working on technologies to develop mines faster, cheaper and with less environmental impact.”

Mining REEs is a dirty business as the ore contains radioactive materials, and processing requires huge amounts of carcinogenic materials like sulphates, ammonia and hydrochloric acid. Processing one ton of REEs produces 2,000 tons of toxic waste.

Baotou, in northern China, is the world capital of REE mining, and it holds more than half of all the country’s production. Baotou produces 10 million tons/year of waste water, which is then pumped into a 10-square-kilometre tailing dam.

This article was originally published in the July 2016 edition of Oilweek.

[Webpage editors note: For the 47 page Summary for Policymakers of the UNEP study go to http://www.apren.pt/fotos/newsletter/conteudos/_green_energy_choices_the... , and the whole 456 page report is available at ]http://www.internationalinsurance.org/files/TC/PDF/-Green_energy_choices... ]