Anaerobic digestion — Anaerobic digestion is the breaking down of biological material by microorganisms under anaerobic conditions. A number of families of bacteria, working together, transform biological material into biogas. There are three main steps in this process:

• Decomposition (hydrolysis) of organic matter contained in manure
• Synthesis of acetic acid out of decomposed matter
• Methane gas formation from acetic acid through the action of bacteria called methanogenic archaea

The bacteria do not need a lot of energy to live and reproduce. For this reason — in contrast to composting — anaerobic digestion produces very little of excess energy in the form of heat. Best conditions for the bacteria are in a very moist substrate or slurry with a temperature around 30 to 35 °C (others work best at 50 to 55 °C).

Biogas — Biogas is a gas mixture that is generated when organic compounds, like livestock manure, is processed in the absence of oxygen (anaerobic digestion or fermentation). Biogas consists of roughly 2/3 combustible methane and about 1/3 carbon dioxide and other gases.

Cap and trade system — An economic approach used to control pollution by providing financial incentives for achieving reductions in the emissions of pollutants. Caps, or emissions targets, are placed on the amount of pollution that can be emitted by a company. The total amount a company can pollute cannot exceed that cap. If the company pollutes above the cap, they need to buy an offset or a credit to reduce their emissions. This creates a market for carbon offset trading.

Under a cap and trade market, the agriculture industry could be exempt from caps on agriculture or livestock emissions and could sell credits by either choosing to reduce GHG emissions or through adopting conservation practices that convert CO² into carbon and store it in farm soils and trees.

Other terms that relate to cap and trade include:

Additionality — Additionality refers to activities above and beyond business as usual (i.e., activities that would have otherwise occurred) that result in the reduction of GHG emissions or sequestration. Proportional Additionality is a different methodology that has been proposed, which considers additionality and the baseline simultaneously.

 

Allowances — Allowances are assigned or auctioned off to capped sector entities or given to an uncapped sector as a means of compensation for good acts or, possibly, to be used as an incentive to promote avoided emissions (as in the case of no-till fields that have already stored their carbon to saturation levels).

 

Carbon credit — Also known as a carbon offset. It describes a financial instrument representing a reduction in GHG emissions. Carbon credits are a key component of emissions trading schemes. They provide a way to reduce GHG emissions by capping total annual emissions and letting the market assign a monetary value to any shortfall through trading. Credits can be exchanged between businesses or bought and sold in national or international markets at the prevailing market price.

Permanence — A term that refers to the time over which sequestered carbon is removed from the carbon; if the reduction or sequestration is forever, then it is considered “permanent.” Typically it is assumed that emission reduction is permanent, and sequestered carbon is not.
Renewable Portfolio Standards (RPS) – Obligates utilities to generate and/or offer to customers a specific amount of electricity from renewable sources.

Renewable Energy Credit (REC) markets — An instrument that represents the positive environmental attributes of energy produced from favored renewable sources. Sometimes called a “green tag.” RECs can be sold into a voluntary market and represent another way that methane digesters producing electricity might command a premium price for their output.

Carbon footprint — A common term for a life cycle assessment, which quantifies the amount of energy used and GHGs emitted for a given product or activity, measured in units of carbon dioxide.

Cogeneration — Also known as combined heat and power (CHP) systems; generates electricity and thermal energy in a single, integrated system.

Enteric fermentation — Fermentation that takes place in the digestive systems of ruminant animals, producing methane gas. Enteric methane emissions are a significant source of GHGs.

Filter strips — Belts of vegetation — grass, shrubs and/or trees — maintained along streams or on the contours of insloping fields to trap sediment and agricultural chemicals before they enter waterways.

Greenhouse gas — Gases that trap heat in the atmosphere are often called greenhouse gases (GHGs). They reduce the loss of heat into space and therefore contribute to global temperatures through the greenhouse effect. GHGs include carbon dioxide, nitrous oxide, refrigerants and methane, among others. These GHGs are expressed in carbon dioxide equivalents (CO²e). Some GHGs occur naturally and are emitted to the atmosphere through natural processes and human activities; others are created and emitted through human activities including, for example, operating power plants and driving vehicles.

Life cycle assessment (LCA) — Quantifies the amount of energy used and GHGs emitted for a given product or activity, measured in units of carbon dioxide. Carbon footprint is a common term for LCA.

Methane — A GHG with 23 times the potency of carbon dioxide.

Nongovernmental organization (NGO) — A nonprofit, voluntary citizens group that is organized on a local, national or international level.

Rotational grazing — Rotational grazing is the practice of dividing up available pasture into multiple smaller areas, called paddocks, and then moving the animals from one paddock to the next after a number of days. By keeping the animals in this one small area, the trampled and grazed plants in other previously occupied parts of the field are given time to recover and re-establish themselves.

Strip farming/cropping — Strip farming is a method of farming used when a slope is too steep or too long, or when other types of farming may not prevent soil erosion. Strip farming alternates strips of closely sown crops such as hay, wheat or other small grains with strips of row crops, such as corn, soybeans, cotton or sugar beets. It is also known as strip cropping. Strip farming helps to stop soil erosion by creating natural dams for water, helping to preserve the strength of the soil.

Sustainability — The dairy industry defines sustainability as providing consumers with the nutritious dairy products they want in a way that makes the industry, people and the earth economically, environmentally and socially better — for now and for future generations.