We are subject to various federal, state and local environmental and health and safety laws and regulations in the United States and at our non-U.S. locations, including those relating to the generation, storage, handling and disposal of hazardous substances, regulated materials and wastes. Certain of these laws and regulations also impose joint and several liability, without regard to fault, for investigation and cleanup costs on current and former owners and operators of real property and persons who have disposed of or released hazardous substances into the environment. Our operations involve the use of hazardous substances and other regulated materials such as petroleum fuel for emergency generators, as well as batteries, cleaning solutions, refrigerants and other materials. At some of our locations, hazardous substances or regulated materials are known to be present in soil or groundwater, and there may be additional unknown hazardous substances, or regulated materials present at sites that we own, operate or lease. At some of our locations, there are land use restrictions in place relating to earlier environmental cleanups that do not materially limit our use of the sites. To the extent any hazardous substances or any other substance or material must be investigated, cleaned up or removed from our property, we may be responsible under applicable laws, permits or leases for the investigation, removal or cleanup of such substances or materials, the cost of which could be substantial.
We purchase significant amounts of electricity from generating facilities and utility companies. These facilities and utility companies are subject to environmental laws, regulations, permit requirements and policy decisions that could be subject to material change, which could result in increases in our electricity suppliers' compliance costs that may be passed through to us. Regulations promulgated by the U.S. EPA or state agencies, or by regulators in other countries, could limit air emissions from fossil fuel-fired power plants, restrict discharges of cooling water, limit the availability of potable water and otherwise impose new operational restraints on power plants that could increase costs of electricity. Regulatory programs intended to promote increased generation of electricity from renewable sources may also increase our costs of procuring electricity. In addition, we are directly subject to environmental, health and safety laws regulating air emissions, storm water management and other environmental matters arising in our business. For example, our emergency generators are subject to state, federal and country-specific regulations governing air pollutants, which could limit the operation of those generators or require the installation of new pollution control technologies. While environmental regulations do not normally impose material costs upon our operations, unexpected events, equipment malfunctions, human error and changes in law or regulations, among other factors, can lead to additional capital requirements, limitations upon our operations and unexpected increased costs.
Regulation of greenhouse gas ("GHG") emissions could increase our costs of doing business, for example by increasing the cost of electricity produced by more GHG-intensive means (e.g., generated from fossil fuels), which could require the management or reduction of GHG emissions (e.g., carbon dioxide capture), or by imposing taxes or fees upon electricity or GHG emissions. In recent years, there has been interest in the U.S. and in countries where we operate abroad in regulating GHG emissions and otherwise addressing risks related to climate change. For example, in the U.S., regulations and legislation have been proposed or enacted during the Biden Administration that limit or otherwise seeks to discourage carbon dioxide emissions and the use of fossil fuels. The change in the U.S. presidential administration may lead to a different regulatory agenda, particularly regarding efforts to limit GHG emissions. Other countries in which we operate may also impose requirements and restrictions on GHG emissions.
Governmental regulations also have the potential to increase our costs of obtaining electricity. Certain U.S. states in which we operate have issued or are considering and may enact environmental regulations that could materially affect our facilities and electricity costs. For example, California limits GHG emissions from new and existing conventional power plants by imposing regulatory caps and by auctioning the rights to emission allowances. Multiple other states have issued regulations (or are considering regulations) to implement carbon cap and trade programs, carbon pricing programs and other mechanisms designed to limit GHG emissions.
To date, regulations aimed at reducing GHG emissions have not had a material adverse effect on our electricity costs, but potential new regulatory requirements and the market-driven nature of some of the programs could have a material adverse effect on electricity costs in the future. Global environmental regulations are expected to continue to change and evolve and may impose upon us new or unexpected costs. Concern about climate change and sustainability in various jurisdictions may result in more stringent laws and regulatory requirements regarding emissions of carbon dioxide or other GHGs. Restrictions on carbon dioxide or other GHG emissions could result in significant increases in operating or capital costs, including higher energy costs generally, and increased costs from carbon taxes, emission cap and trade programs and renewable portfolio standards that are imposed upon our electricity suppliers. These higher energy costs, and the cost of complying across our global platform or of failing to comply with these and any other climate change regulations, may have an adverse effect on our business and our results of operations. The course of future legislation and regulation in the U.S. and abroad remains difficult to predict and the potential increased costs associated with national or supra-national GHG regulation and other government policies cannot be estimated at this time.