For cities like Toronto, the garbage management process is multifaceted and problematic. Households, apartments, and condos have multi-coloured bins for recyclable plastic, metal, paper (blue), organic recyclables (green), and what is disposable (grey). The city collects from homes with curbside pickup and delivers the blue bin recyclables to warehouses where the stuff is sorted and stashed awaiting buyers who can turn the collected material into new products. The green bin recyclables are collected to turn into compost which the city uses for parks and other green spaces, and gives away to residents at community recycling events. The grey bin garbage goes to landfill sites with one even in neighbouring Michigan. That’s right. Toronto exports garbage to the United States and we pay an American landfill operator to take it. At one point Toronto was considering sending its non-recyclable garbage to an abandoned open-pit iron mine site some 600 kilometers (almost 400 miles) north of the city.

Proposals to incinerate garbage have always been opposed by Toronto politicians on the grounds that pollutants produced from burning impact air quality, add greenhouse gases to the atmosphere, and produce ash waste that can be filled with unknown quantities of toxic metals and chemicals. But in other urban centers where landfill options are limited, incineration is seen as a solution to the garbage problem.

Singapore is the latest city to see garbage in a “waste-to-energy” light. Because the city has very little real estate it can waste on waste, it has opened a new facility, the Innovation Centre for Environmental Technology, where research by a Japanese company, JFE Engineering, is developing direct melting gasification, a technology that burns garbage leaving only slag (which can be put into landfill), metal, and other potentially commercial end products.

Meanwhile in Duiven, The Netherlands, the Dutch waste to energy company, AVR, is building a waste-to-energy plant which includes large-scale carbon capture and utilization (CCUS) capability. After the waste is burned 60,000 tons of carbon dioxide (CO2) will be captured and liquefied for transport to the French company, Air Liquide, who will use the gas in Dutch greenhouse operations where vegetables, fruit, flowers, and other plants are grown. The capacity of the CCUS technology can only manage 15% of the total CO2 emissions produced, but AVR expects to find additional customers with a goal to eventually capture and reuse 800,000 tons annually. Other potential customers include manufacturers of building materials, concrete, plastics, and biofuels. The biofuels produced could even be used to heat the greenhouses through the Dutch winter.

But the ultimate waste-to-energy technology is one that produces zero emissions. Companies and inventors have come and gone claiming to have found the solution for economically turning waste into energy without contaminating byproducts. One such is ZEROS System, a Highlands, Texas-based company just to the east of Houston. Its website describes the Zero-emission Energy Recycling Oxidation System capable of disposing of waste and turning it into energy and useful products while producing no emissions. ZEROS, based on patents first issued in the 1980s, has been used once in remediating an oil field accident. But other than that has yet to have attracted a customer to implement its stackless technology. As you read the content of the website it sounds too good to be true. Finding corroborative evidence to support the site’s claims yields next to nothing. The last report on the technology looks at economic feasibility. It was written in 2011. And then there is a 2013 YouTube video.

The search for the zero or negative-zero emissions holy grail is still on. Maybe the new Singapore initiative or the work being done in The Netherlands will finally produce it. I’ll keep you posted.

The post Can Burning Trash Become a Net-Zero Emissions Source of Energy? appeared first on Techso Mogro.

Today global renewable energy capacity totals 1,274 Gigawatts. How does this compare to all the energy we consume? If U.S. consumption is an indicator renewable is just a small fraction of the total. For example, wind, solar and other non-hydro renewable energy sources generated 126 TWh of electricity in the United States in 2008, double the 64 TWh of output in 1990. The percentage share from non-hydro renewable sources  amounted to 3.1% up in 2008 from 2.1% in 1990. Hydroelectric production in contrast dropped from 8.9% to 6.2%.

Compare those numbers to coal, oil and natural gas. Coal-generated electricity in the U.S. dropped as a percentage from a 51.8% in 1990 to 48.2% in 2008. In total power produced, however, coal dramatically increased. Petroleum also dropped as a percentage from 3.6% to 1.1% with little increased capacity. But natural gas on the other hand increased dramatically both in the amount of power generated and as a percentage of total generating capacity, growing from 14.7% to 21.4% over the same period.

What are renewable energy sources? They include hydroelectric from water, wind turbines, solar arrays, tidal and wave power turbines, and geothermal. Some of these energy generation types are carbon neutral but other renewable sources have a significant carbon footprint. Most of these sources can be used to generate power continuously without depleting the energy source from which the electricity is derived. Hydroelectric, however, has some significant challenges.  A brief discussion of each follows.

Hydroelectric

Humanity has been converting falling and flowing water into energy for centuries. In fact water represents the single largest contributor to global renewable energy sources on the planet today. We classify the conversion of water power to electricity under the name hydroelectricity or hydro for short. Today hydro projects generate almost one quarter of the world’s electricity usually through sites where there are natural waterfalls or through the damming of rivers to create artificial drops.

The world is running out of usable new sites of this type. This is compounded by environmental concerns. Gradients are critical in establishing enough force for water to turn turbines connected to generators, but dams  are extremely disruptive to the wildlife in rivers, the population displaced by flooded lands,  and for people living downstream from the sites. In addition damming of rivers changes how they deposit silt. Many current dams are dealing with significant build ups of silt in their reservoirs leading to a decline in reservoir capacity. These are just some of the reasons that the 21st century will see hydroelectric power projects not at sites like Three Gorges Dam on the Yangtze River in China, but in smaller locales with less environmental consequences.

Wind

Harvesting the latent energy of the atmosphere has been one of humanities great technical achievements.  From windmills to sails we have been using the energy of wind to power machinery from the milling of grain to trans-oceanic expeditions on sailing ships. Farms in rural North America were often not connected to the electrical grid and used the wind as a power source for pumping well water, milling and other purposes. Today wind power is becoming a significant source of electrical power in many countries through the development of large wind farms featuring turbines that can be several hundred meters in height with propeller vanes as large as 60 meters.

The average individual wind turbine generates enough electricity to power 600 homes when the wind is blowing. Wind farms tend to have a cluster of turbines from as few as ten to hundreds. Once installed operational costs are practically non-existent. The real challenge is the reliability of wind as a power source. When it doesn’t blow no energy can be produced making wind less reliable than hydro and other renewable sources.

Wind turbines have been blames for the killing of migratory birds and bats. Many people fear having them installed near their homes because of medical and environmental concerns. Others don’t want a forest of these giant windmills dotting their shorelines or fields on purely aesthetic grounds. Yet despite consumer resistance wind power continues to grow globally with global capacity reaching 70,000 Megawatts in 2009. At the present rate of growth wind power may contribute as much as one-third of the world’s electrical generation capacity by the mid-21st century.

Solar

All the energy of the atmosphere comes from the warming effect of our sun including wind and the water cycle that gives us the ability to harness water. Even biomass derives its energy from the sun which is then converted into plant material. But when we talk about solar energy we are usually referring to the renewable energy generated through a number of technological inventions.

What makes solar energy so attractive is its abundance. The sun is always shining somewhere on the planet and when you look at the amount of energy that reaches the surface even on cloudy days the numbers dwarf our current energy generating capacity. In fact, the upper atmosphere of our planet receives the equivalent of 174 petawatts (PW) of incoming solar radiation of which 30% is reflected back into space with the rest getting absorbed by our atmosphere, oceans and land.  To put this in perspective in terms of our average requirement versus the amount of solar energy available, let’s look at Australia as an example. That continent receives 15,000 times the amount of energy it currently generates from all other sources through solar.

Although passive solar has been the traditional way humans have used the sun’s energy historically, it is the advent of photovolatics (PV) where research and development is focused today. What we call solar cells are used to convert sunlight directly into electricity. The manufacture of solar cells and photovoltaic panels is a growing industry. The  industry-wide challenge is to maximize the efficiency of these devices in their ability to convert the sun’s energy intro a reliable power source.

Ultimately the evolution of 21st century photo-exchange technologies should yield artificial photosynthesis and the almost unlimited energy that we will derive from solar as a result.

Tidal and Wave

We owe the moon a lot. The gravitational forces it exerts on the world’s oceans create an enormous amount of energy in the form of tides. In addition wind blowing over open ocean has enormous energy potential. What exactly is the total potential of tides and waves?

It is estimated at 2-3 million megawatts. The Bay of Fundy off the eastern coast of Canada, the western coast of the United States and Europe, the coast of Japan and coastal New Zealand are considered to be the best sites for harnessing energy derived from waves and tides.

At the beginning of the 21st century we are only beginning to experiment with the right kind of engineering designs to to harness wave energy effectively. Today there are only small commercial wave energy projects in place but the ability to harvest the latent energy potential should yield significant breakthroughs in the near future. The immediate benefit with small wave and tidal energy plants is the effective delivery of power to local and often isolated shoreline communities.

Geothermal

Geothermal energy is derived from two types of sources, one natural and the other helped along by human intervention. For example, natural geothermal can be found in New Zealand and Iceland, where below ground heat sinks represent an enormous energy resource. New Zealand generates approximately 10% of its electricity from geothermal sources. Iceland derives 23% of its electrical energy this way.   Other countries with existing geothermal programs include Italy and Japan. California has an active geothermal program as well. And the rest of the world is sitting up and taking notice.

Geothermal resources can be classified as high, moderate and low  temperature.

High temperature geothermal is usually located on the edge of continental plates (New Zealand and Iceland for example) where magma from the Earth’s mantle is close enough to the surface that the heat from the melted rock is reachable. Typical magma heat sources provide temperatures between 200- 350 degrees Celsius at accessible depths.

Moderate temperature geothermal is usually associated with fault lines. California, Italy and Japan have these types of deep faults. Geothermal sources of this type have temperatures at accessible depths of approximately 140 degrees Celsius. This type of resource is often found close to high temperature geothermal sources.

Far more common is low temperature geothermal. A typical low temperature geo-exchange system involves drilling a number of holes in the ground to depths between 90 and 110 meters where temperatures year-round are a consistent 13 degrees Celsius. Pipes inserted into the holes are used to pump water or other heat conducting fluids. The closed system is combined with a heat exchanger, providing air conditioning in the summer and heat in the winter. In Iceland 89% of homes use heat exchangers to provide warmth in the winter.

Geothermal is a clean energy resource and low temperature geo-exchange can be implemented widely with a reasonable cost recovery whether large scale or for single residential use. The 21st century should see a rapid expansion in use of this low emission energy resource.

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