An overwhelming majority of scientists around the world agree that climate change is occurring and that it is at least in part due to human activity. Carbon dioxide (CO2) is the largest contributor, simply because so much of it is emitted from so many sources. The United States emits over 5.5 billion tons of CO2 each year. New York State is responsible for roughly 245 million tons of that, nearly all of which is produced by fossil-fuel combustion (e.g., power plants, vehicles).
In 2006, NYSERDA initiated its climate change research program under EMEP. Joint research planning with the New York Academy of Sciences and stakeholders identified near-term and long-term research goals for New York in the area of climate change, including evaluating the potential of energy efficiency and renewable energy to reduce greenhouse gas emissions in New York State; climate change policy research and analysis; assessing climate change impacts and adaptation strategies in New York State; and determining the feasibility of geological carbon storage—or "sequestration"—within the state.
Controlling Carbon Dioxide
To slow down climate change, CO2 emissions must be controlled. Experts have identified several options to help reduce these emissions, including increasing energy efficiency and energy conservation; switching to non-carbon-based fuels such as solar or wind power, nuclear power, or hydrogen power; and sequestering, or storing, CO2 underground. However, there is no single strategy that will result in the necessary reduction of CO2 emissions. 
New York State is taking steps to confront the problem, including the Regional Greenhouse Gas Initiative and New York's "15 by 15" plan to reduce electricity consumption 15 percent by the year 2015. Emissions need to be cut so drastically that all options must be considered, including carbon capture and sequestration. Princeton University's Carbon Mitigation Initiative (CMI) has created the "stabilization wedge" concept to explain the issue more clearly. CMI's two-page primer describes the concept; note, however, that due to increasing carbon emissions, eight wedges will now be needed, not seven.
Carbon Capture and Storage
With carbon capture and sequestration (CCS), sources currently emitting CO2 to the atmosphere instead capture the CO2 inject it into underground rock formations, where it then remains underground instead of contributing to climate change. To ensure that as much CO2 as possible can be injected into a particular formation and that the CO2 won't interfere with usable groundwater and other resources, the rocks should be at least 2500 feet below the surface. For explanations of how CCS works and why the CO2 stays underground, see the International Energy Agency's publications titled Storing CO2 Underground and Geologic Storage of Carbon Dioxide: Staying Safely Underground.
The idea of storing CO2 in rocks is not far-fetched. Carbon dioxide, natural gas, and oil exist naturally in rocks and have been there for millions of years. Oil and natural gas production for fuel uses similar technologies that would be needed for sequestration. Natural gas produced for fuel is routinely re-injected into the ground to be stored until it is needed, and CO2 is often injected into oil fields to increase production. Carbon sequestration is essentially oil and gas geology in reverse!
Because sequestration is a fairly new undertaking, it is not without uncertainties. Unlike natural gas storage, which is engineered so the gas can be easily re-extracted, CO2 will be stored indefinitely. It will also be injected much deeper than most natural gas storage reservoirs. To ensure that storage will be safe and long term, detailed geological research will be necessary prior to siting. The CO2 will need to be monitored during and after injection. In the United States, neither state nor federal regulations are currently in place for safe transport and injection of CO2. Still, small-scale tests have been successful in the U.S., and larger, commercial operations around the world have successfully injected millions of tons of CO2 with no sign of leakage.
Capturing CO2 emissions and storing the gas in underground geological formations could significantly reduce the amount of CO2 released to the atmosphere. 
Because geology varies widely throughout New York State, however, detailed geological research needs to be conducted to determine which rocks are capable of storing CO2. NYSERDA recognizes the importance of carbon sequestration and has several relevant projects underway. These projects are currently funded through the EMEP Program. Additionally, through NYSERDA and the New York State Museum (NYSM), New York has recently become a member state of the U.S. Department of Energy's Midwest Regional Carbon Sequestration Partnership (MRCSP), one of seven regional partnerships tasked with studying CCS options throughout the country.
Underground CO2 Storage Possibilities in New York State
Saline Formations
In New York State, the most likely rock formations to be targeted for CO2 storage are saline formations-deep, porous rocks containing very salty water (often six times saltier than seawater). The water contained in these formations is much too salty to be potable, so injecting CO2 into these formations will not affect drinking water supplies. The NYSM produced a preliminary map of the likely areas in New York where CO2 could be stored in saline formations. These rocks are deep enough and are the right type for CO2 storage, but much more detailed geological research is needed.
Gas and Oil Fields
CO2 could also be stored in mature natural gas and oil fields that are reaching or have reached the end of their productive life. Injecting CO2 into these reservoirs could push out more gas or oil that would otherwise remain underground. This process is called enhanced oil (or gas) recovery (EOR/EGR). In addition to storing CO2, EOR and EGR result in an economic gain. The southwestern portion of New York State contains numerous gas fields where EGR could be practical. (The few oil fields that exist in New York are too few and too shallow for EOR to be practical for large-scale storage.)
Shale Sequestration
Sometimes natural gas is produced from a certain type of rock called organic shale. Injecting CO2 into these shales may enhance any existing gas production (another form of EGR), while also storing CO2. This process is still in the early stages of research, but if proven to work, a large area of New York State could be opened up to CO2 storage in shales.
Capacity Estimates
It is difficult to estimate the amount of CO2 that a formation could hold. It requires extensive geological research and modeling. Because New York State is only beginning to study CCS, capacity estimates have not yet been calculated. Preliminary measurements of some New York formations are promising, however. The blue areas in this magnified photo of a New York sandstone are spaces that CO2 could fill.
Other Sequestration Opportunities
Underground sequestration may not be the only way to indefinitely store captured CO2. Terrestrial sequestration can also reduce emissions. This means increasing the amount of carbon that plants and soils naturally store. For example, trees planted to reforest abandoned mines would use CO2 as they grow, and changing agricultural practices to include no-till farming would keep CO2 in the soil that would otherwise be released when the land is tilled. In the near future, NYSERDA will be studying the terrestrial sequestration options in New York State.
In addition, NYSERDA currently manages several projects investigating alternative methods of sequestration in the early stages of development. These include CO2 capture by algae, which could then be processed to create a liquid biofuel; converting CO2 to a solid, stable mineral; and storing CO2 beneath the ocean floor.
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