How We Can Turn Plastic Waste Into Energy

(The Conversation) In the adventure classic Back to the Future, Emmett “Doc” Brown uses energy generated from rubbish to power his DeLorean time machine. But while a time machine may still be some way off, the prospect of using rubbish for fuel isn’t too far from reality. Plastics, in particular, contain mainly carbon and hydrogen, with similar energy content to conventional fuels such as diesel.

Plastics are among the most valuable waste materials – although with the way people discard them, you probably wouldn’t know it. It’s possible to convert all plastics directly into useful forms of energy and chemicals for industry, using a process called “cold plasma pyrolysis”.

Pyrolysis is a method of heating, which decomposes organic materials at temperatures between 400℃ and 650℃, in an environment with limited oxygen. Pyrolysis is normally used to generate energy in the form of heat, electricity or fuels, but it could be even more beneficial if cold plasma was incorporated into the process, to help recover other chemicals and materials.

Related: How to Detox From Plastics and Other Endocrine Disruptors

The case for cold plasma pyrolysis

Cold plasma pyrolysis makes it possible to convert waste plastics into hydrogen, methane and ethylene. Both hydrogen and methane can be used as clean fuels, since they only produce minimal amounts of harmful compounds such as soot, unburnt hydrocarbons and carbon dioxide (CO₂). And ethylene is the basic building block of most plastics used around the world today.

As it stands, 40% of waste plastic products in the US and 31% in the EU are sent to landfill. Plastic waste also makes up 10% to 13% of municipal solid waste. This wastage has huge detrimental impacts on oceans and other ecosystems.

Of course, burning plastics to generate energy is normally far better than wasting them. But burning does not recover materials for reuse, and if the conditions are not tightly controlled, it can have detrimental effects on the environment such as air pollution.

Related: Many Hand-me-down Plastic Toys Are Toxic for Kids

In a circular economy – where waste is recycled into new products, rather than being thrown away – technologies that give new life to waste plastics could transform the problem of mounting waste plastic. Rather than wasting plastics, cold plasma pyrolysis can be used to recover valuable materials, which can be sent directly back into industry.

How to recover waste plastic

In our recent study we tested the effectiveness of cold plasma pyrolysis using plastic bags, milk and bleach bottles collected by a local recycling facility in Newcastle, UK.

We found that 55 times more ethylene was recovered from [high density polyethylene (HDPE)] – which is used to produce everyday objects such as plastic bottles and piping – using cold plasma, compared to conventional pyrolysis. About 24% of plastic weight was converted from HDPE directly into valuable products.

Plasma technologies have been used to deal with hazardous waste in the past, but the process occurs at very high temperatures of more than 3,000°C, and therefore requires a complex and energy intensive cooling system. The process for cold plasma pyrolysis that we investigated operates at just 500℃ to 600℃ by combining conventional heating and cold plasma, which means the process requires relatively much less energy.

Related: Microplastics in Sea Salt – A Growing Concern

The cold plasma, which is used to break chemical bonds, initiate and excite reactions, is generated from two electrodes separated by one or two insulating barriers.

Cold plasma is unique because it mainly produces hot (highly energetic) electrons – these particles are great for breaking down the chemical bonds of plastics. Electricity for generating the cold plasma could be sourced from renewables, with the chemical products derived from the process used as a form of energy storage: where the energy is kept in a different form to be used later.

The advantages of using cold plasma over conventional pyrolysis is that the process can be tightly controlled, making it easier to crack the chemical bonds in HDPE that effectively turn heavy hydrocarbons from plastics into lighter ones. You can use the plasma to convert plastics into other materials; hydrogen and methane for energy, or ethylene and hydrocarbons for polymers or other chemical processes.

Best of all, the reaction time with cold plasma takes seconds, which makes the process rapid and potentially cheap. So, cold plasma pyrolysis could offer a range of business opportunities to turn something we currently waste into a valuable product.

The UK is currently struggling to meet a 50% household recycling target for 2020. But our research demonstrates a possible place for plastics in a circular economy. With cold plasma pyrolysis, it may yet be possible to realise the true value of plastic waste – and turn it into something clean and useful.The Conversation

Anh Phan, Lecturer in Chemical Engineering, Newcastle University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

There are better ways to foster solar innovation and save jobs than Trump’s tariffs

President Donald Trump’s decision to impose punitive duties on imported solar panels and related equipment is rankling most of the industry.

This was the final step of a process that began when two U.S. subsidiaries of foreign solar panel makers filed a rarely used kind of trade complaint with the International Trade Commission. Trump largely followed the course of action the independent U.S. agency had recommended to protect domestic manufacturers from unfair competition.

But far from protecting U.S. interests, the tariffs are bound to stifle the current solar boom, destroying American jobs and dragging down clean energy innovation. As economists who research climate and energy policies that can foster a greener North American economy, we argue the government should instead create targeted subsidies that support innovation and lower costs across the supply chain. This approach would do a better job of helping the U.S. industry fend off foreign competition without harming the industry itself.

A booming industry

The U.S. solar industry has enjoyed unprecedented growth in recent years, thanks to the rapidly declining cost to install solar systems and tax breaks for homeowners, businesses and utilities that have expanded demand but are being phased out. Prices have plunged to roughly US$1.50 per watt from around $6 in 2010 due to both innovation that made it less expensive to make panels anywhere and cheap imports.

In 2016, 87 percent of U.S. solar installations used foreign-produced panels, also known as modules, primarily from China.

The rapid decline in solar panel costs has been driven by policies in China and elsewhere intended to expand domestic manufacturing of these products.

The problem is not unique. Other countries dependent on cheap solar imports, including Germany and Canada, are also grappling with how to sustain the solar boom while protecting their own domestic manufacturers from unfair foreign competition.

The trade commission sent Trump its recommendations in the fall of 2017, giving him until Jan. 13 to accept or reject its guidance. Later, U.S. Trade Representative Robert Lighthizerasked the agency to draft a “supplemental” report, which effectively extended the president’s deadline for setting the tariffs.

The request, observers surmised, may have signaled concern about the this case’s potential to spiral into a broader trade dispute with China and other major U.S. trading partners.

That may explain why the duties imposed are not as steep as the maximum 35 percent ratethe U.S. International Trade Commission had recommended. The tariffs will begin at 30 percent and then taper down in 5 percent increments over four years, ending at 15 percent in 2022. And they won’t apply to the first 2.5 gigawatts worth of imported solar cells, which domestic manufacturers use to build panels made in the U.S.

Solar job growth

Solar job growth took off in 2010. By 2016, more than 260,000 Americans worked in the industry, up from fewer than 95,000 seven years earlier.

An uninterrupted solar boom would create even more jobs. The number of solar panel installers, for example, would more than double from 11,300 to 23,000 within 10 years at the current pace of growth, which would make it the fastest-growing profession, according to the Bureau of Labor Statistics. Another renewable energy mainstay, wind turbine technician, came in a close second.

Imposing tariffs on imported panels would cloud that outlook, largely becausemanufacturing accounts for less than 15 percent of U.S. solar jobs while installation amounts to more than half of them, according to the Solar Foundation’s annual census. If panels get more expensive, the cost to go solar will rise and demand will fall – along with the impetus to employ so many installers.

The Solar Energy Industries Association, a trade group that represents many companies in the industry, objected to the new duties, saying they could cost the industry 23,000 jobs in 2018.

Smarter subsidies

Despite the robust growth in wind and solar employment and its official support for an “all of the above” energy policy that combines fossil fuels, nuclear power, biofuels and renewable energy alternatives like wind and solar, the Trump administration has sought to slash support for alternative energy through the federal budget.

We agree that the government should encourage solar panel manufacturing within the nation’s borders. But there are better ways to support this important priority than by raising prices on imported equipment through punitive tariffs.

China’s edge in solar panel manufacturing – apart from low wages – is driven by scale and supply-chain development, spurred by cost inducements like low-interest loans, technology development assistance and cheap land. Other newly industrialized countries like South Korea and Taiwan have followed China’s lead by fostering their own solar manufacturing bases with targeted subsidies.

We believe the U.S. should follow suit. In addition to directing subsidies to reduce the costs of the solar supply chain, the government should also increase subsidies for private research and development for green innovation. Currently, federal financing for private solar R&D lags far behind levels seen in China and the European Union.

These subsidies could be funded by the tariffs the government was already collecting on solar panels imported from China and elsewhere before these new duties were considered.

If the U.S. government deems that additional restrictions are required, then it makes sense to follow a separate recommendation to freeze solar panel imports at 2016 market share levels. The government should then auction off the rights to import foreign solar panels to U.S. installers.

The government could spend the proceeds from these auctioned import licenses on domestic innovation and other efforts to cut supply chain costs for U.S. manufacturers of solar panels and related equipment.

While World Trade Organization rules limit the use of subsidies that explicitly promote a country’s exports in global markets, the ones we are proposing would likely be WTO-compliant.

This is because their aim is to make the U.S. solar industry more competitive within the domestic market, given the government’s earlier findings that cheap imported panels are being dumped – sold too cheaply – here.

Why make an exception

Like most economists, we believe that subsidies should be avoided except in special circumstances. Here are three reasons why this industry is an exception.

First, when one nation subsidizes solar panel production and exports those panels, it makes it cheaper to go solar in other countries, effectively cutting the cost of implementing climate policies abroad.

Second, when solar energy replaces fossil fuels in one place, the declining carbon emissions benefit people around the globe. Climate change, after all, affects the entire world.

Third, R&D investments made in any one economy eventually add to the global knowledge base. Improving solar technology will ultimately benefit the entire industry worldwide.

The Trump administration’s solar tariffs will yield none of these benefits. In fact, they could instigate a trade war over clean energy products with our trading partners globally.

That is why we believe that the smarter subsidies we are proposing are a better way to sustain the U.S. solar industry and protect jobs.