http://www.cleanenergy.org/2009/03/18/biopower-overview/

SACE | Southern Alliance for Clean Energy

Biopower Overview

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pine.jpgBiopower is the use of agricultural and forest materials for steam, heat, and electric generation. Biopower is produced when organic material is burned to make steam to push a generator. This material, called biomass, is most often the byproducts left over from the forest, food, and fiber industries.

The kind of biopower facilities that burn biomass to make steam for a generator are most common. However, a few biopower facilities convert biomass into a gas, which is then fired in a turbine to generate electricity. Other facilities are optimized to produce steam for both heating and electric generation, and these are called CHP or combined heat and power. Further advancements in CHP allow the steam energy to be converted to refrigeration, and these are called absorption chillers. These less common kinds of biopower facilities are more efficient, thus more environmentally preferable.

Biopower is the largest source of renewable energy in the world, other than hydroelectricity. According to U.S. Department of Energy’s office of Energy Efficiency and Renewable Energy (EERE), as of May 2005 there was over 7,800 megawatts of biomass power capacity in 350 locations in the United States. This operating capacity generates approximately 44 billion kilowatt-hours per year, an amount equivalent to the electricity used by 4.5 million average U. S. homes. Here in the SACE territory (FL, GA, NC, SC, TN), we estimate biopower capacity to be 4,388 megawatts (installed or announced facilities).

These figures only hint at the overall potential for renewable energy from biomass. SACE estimates maximum feasible biopower generation potential at 95,630 GWh in the 13 state Southern region.

The Southeast is the region with greatest growth potential for biopower. Because of our long growing season and favorable climate, the Southeastern states are sometimes called the “Saudi Arabia of Biomass.” In fact, the summer of 2008 saw significant proposals by electric utilities and others to build new biopower plants, to convert old coal-fired plants to burn biomass, or to upgrade coal-fired plants to burn small percentages of biomass in a process called co-firing.

This is because biopower can be implemented relatively more quickly than large-scale wind power and solar energy. And when coal is selling at prices over $100 per ton, the economic pressure to convert to biomass is considerable.

What kind of biomass do these biopower plants consume? Currently, biopower plants in the Southeast consume mostly waste materials. This includes logging debris, wood waste from sawmills, urban tree trimmings, old pallets, and used railroad ties. For many years paper mills have been generating heat and power from black liquor, a lignin-rich liquid byproduct of paper-making. Sugar refineries have been making heat and power from the residue of sugar cane, called bagasse. Agricultural byproducts like rice hulls and cotton waste are also familiar biopower feedstocks.

Biopower developers are hoping to move into newer biomass feedstocks, like poultry litter, short-rotation woody crops (i.e., hybrid poplar or willow), or even specially grown bioenergy crops like miscanthus (a giant grass) or arundo donax (a giant reed).

A different type of biopower can be found in the conversion of animal waste into methane for energy recovery. Hog farms and cow dairies install a device called an anaerobic digester, which uses biological processes to convert the manure into methane gas, which can then be cleaned and burned for heat or electricity.


What are the Obstacles or Challenges?

Progress is already being made to make biopower more cost-competitive in the market as well as more efficiently produced in large-scale applications. Bioenergy can become a solid competitor in the marketplace due to the advancement of energy conversion technologies and federal and state incentives. To help give these technologies a jumpstart, Federal and State governments need to adopt sound renewable energy policies, such as renewable energy standards, net metering and interconnection standards, so that biopower can be easily incorporated into utilities’ overall energy mix.


What are the Benefits of Biopower?

* Reduces Pollution

  • Unlike coal, biopower emits no mercury.
  • Biopower emits less sulfur dioxide pollution than coal. Sulfur dioxide is a leading cause of haze and particulate matter that can damage the lungs and cause heart attacks.
  • Burning biomass can be carbon neutral. The carbon dioxide, a global warming gas, released into the atmosphere when creating biopower is burned and absorbed by growing plants, which are later processed into energy.
  • In the case of biopower from hog farm and cow dairy lagoons, because methane is such a powerful greenhouse gas (GHG), the destruction of this gas is critical to fighting climate change. One ton of methane produces the same GHG effect as 23 tons of CO2.

* Improves local economy and small businesses/technology

  • Biopower helps displace coal, an energy source which causes the Southeastern region $8 to $16 billion per year in economic leakage.
  • Biopower feedstock comes from woodlands and agricultural farmland, which supports more jobs and revitalizes rural economies.
  • The agricultural products used for biopower do not compete with existing crops because most of the biopower development comes from using agricultural waste products. Further, dedicated bioenergy crops (i.e. switchgrass) are typically grown on less fertile land, saving the best land for food crops.

Biopower production and development will also create a new diversified market of jobs for utility and power plant vendors, owners/operators, agricultural equipment vendors, and the technology development industry.


Solutions

What are the methods used to convert agriculture and forest feedstocks into electricity? There are five major types of biopower systems:

  • Direct-Fired Systems – Direct-fired systems burn biopower feedstocks directly to heat a boiler, producing steam. The steam is captured by a turbine and then converted into electricity by a generator. The steam can also be used for any manufacturing process or direct heating system. These facilities are known as combined heat and power facilities (CHP). For instance, wood waste is often used to produce both electricity and steam at paper mills. Direct-fired systems are the most common method used to produce electricity from agriculture and forest materials.
  • Co-Firing – Co-Firing uses biopower feedstocks in high-efficiency coal–fired boilers as a means of reducing overall emissions of the coal-fired power plant essentially by reducing the amount of coal burned. Using biomass in a coal-fired boiler with coal is one of the easiest and cheapest ways to reduce emissions because agriculture and forest materials burn cleaner than coal and can be burned using the existing power plant.
  • Pyrolysis – Pyrolysis is a process in which biopower feedstocks are heated in the absence of oxygen, which causes the feedstocks to decompose into gases, liquids, and solids. Most of the products created from this process can be used as fuels for energy production or can be used for the production of various materials and chemicals.
  • Gasification – Gasification is a process in which biopower feedstocks are heated in the absence of oxygen (or minimal oxygen) with controlled moisture or steam to produce a syngas. This syngas (or biogas) is then used as a fuel for a combined cycle power generation plant. A combined cycle power generation plant is highly efficient. Existing natural gas-burning equipment can be modified to use syngas or biogas, including electrical generators, heaters and vehicles.
  • Anaerobic Digestion – Anaerobic digestion is a natural or artificially occurring process in which organic material is decomposed by bacteria in the absence of oxygen. This process produces methane along with other gases such as carbon dioxide. Commonly, methane is produced in landfills where anaerobic digestion occurs naturally. However, progress has been made in developing methane through anaerobic digestion of manure, mainly cattle and pig waste. Anaerobic digestion transforms manure into methane, leaving behind marketable compost, fiber, and nutrient-rich water. Anaerobic digesters can reduce odor from manure by more than 90% and can help reduce water pollution from large animal farms. Additionally, most forms of biopower systems do not require water for the electricity production process. Existing natural gas-burning equipment can be modified to use methane (or biogas), including electrical generators, heaters and vehicles.

What SACE is doing?

  • Tracking development of new and expanded biopower production facilities, to assess the impact on the available biomass resource base.
  • Promoting a Federal Renewable Energy Standard (RES) with definitions of biomass that will allow the industry to grow without compromising the environment.
  • Organizing dialogues among stakeholders to define the issues, seeking consensus around appropriate responses.

What You Can Do:

  • For information on biopower in the North Carolina’s Renewable Portfolio Standard
  • Get involved in the RPS rulemaking process in Florida and the REES rulemaking process in North Carolina.
  • Support sustainable biopower development projects, such as Georgia Power’s recent proposal to convert Plant Mitchell in Albany, GA from coal facility to a biomass facility.

Sustainability of Bioenergy

Overview

The potential for bioenergy in the Southeastern states is massive. Some have called the region “the Saudi Arabia of biomass.” Biomass, such as wood, has been utilized for centuries to heat homes and supply electricity. Much of this continues to happen today, but on a small scale. But fossil fuels, such as coal, nuclear and natural gas, have been utilized as the primarily sources in our region.

In general, it can be implemented sooner than large-scale wind power and solar energy. This is why we are seeing electric utilities voluntarily starting large biopower projects. These commercial developments show us that bioenergy is needed now more than ever before, to help counter our changing climate, rising fossil fuel pollution, increasing prices of coal and petroleum, and the weakening regional economy.

However, just because biofuels and biopower are renewable energy does not mean that they are always sustainable. Taking a lesson from corn ethanol’s rapid growth and unintended consequences, sustainable biofuels and biopower must be developed with forethought and consideration of the environment and future generations. We at SACE are working with many partners in the public and private sectors to ensure that these important industries are built with sustainability in mind.


Negative Impacts

Some of the current concerns about the sustainability of biofuels question the impacts on soil quality and erosion, water consumption and pollution, greenhouse gas emissions, air quality, wildlife and biodiversity, food and feed production and prices, as well as land-use changes.

Similar concerns are being examined with production of electricity from biomass (biopower). However, because the predominant biopower resource is biomass from trees and forests, one of the greatest concerns is the competition for feedstocks: As these industries grow, we have the potential for several industries to compete for the same feedstock. Wood-based biofuels biorefineries may find themselves competing with power plants for the same wood waste. The existing paper, pulp, fiber, and wood products industries are concerned that bioenergy may increase the price of their feedstocks. In these cases, SACE is concerned that too much demand for wood concentrated in one geographic area may result in depletion of the biomass resource, or damage to the soil, or lapses in the Best Management Practices that protect our water quality and quantity in forested regions.


Solutions

How do we ensure sustainability in bioenergy?

We at SACE are partnering with industry and collaborating with researchers and other organizations to develop and promote measures for sustainable biofuels and biopower. Here are some practices and policies that will help us achieve sustainability:
California’s Low Carbon Fuel Standard for biofuels
The Roundtable on Sustainable Biofuels’ Draft Principles and Criteria
Sustainable Harvesting Guidelines
Best Management Practices
Definition of Biomass
Renewable Fuels Standard (RFS)
Renewable Portfolio Standard (RPS)

What SACE is doing?

  • Tracking development of new and expanded biofuels and bipower production facilities, to assess the impact on the available biomass resource base
  • Organizing discussions of issues surrounding sustainability
  • Organizing dialogues among stakeholders to define the issues, seek consensus around appropriate responses.
  • Promoting Federal Renewable Portfolio Standard (RPS) with definitions of biomass that will allow the industry to grow without compromising the environment.
  • Increasing awareness of Low Carbon Fuel Standards