Though not a regularly-used term, sustainable infrastructure refers to anything built or used in a way that contributes to the overall sustainability of natural resources. In most cases, this is related to energy consumption and water use, two of the most high profile conservation areas. Though there is no firm definition on what constitutes sustainable infrastructure, efficiency over previous generations of technology and construction is a must.
Despite the typical emphasis with this term on transportation, this is just one of the areas were sustainable infrastructure can make a difference. Sustainable architecture can help reduce the energy consumption of buildings by using, among other things, energy-efficient windows and better environmental systems. Some even include more recent innovations such as solar energy panels or green roofs.
Regarding water usage, sustainable infrastructure often means assuring that the water supply is safe, consistent, and in good shape. Leaks and contaminants getting into a water supply can severely limit a system's efficiency and lead to a great deal of wasted resources. To combat this problem, many water utilities invest a significant portion of revenue in an ongoing capital improvement plan and purification. Together, these help promote sustainable practices.
Reservoirs may be another factor in sustainable infrastructure. These vast stores of water allow arid regions to tap into a very consistent supply. Though there may be times when a reservoir drops to dangerously low levels, this is usually an extreme situation caused only by severe drought. Reservoirs also have their critics, however. Many feel that trapping water upstream cuts off lifelines to those living downstream.
Regarding energy consumption, sustainable infrastructure means putting the pieces in place that can help reduce the dependence on fossil fuel, a non-renewable energy source. This may include developing mass transportation alternatives such as light rail, subways, and bus routes. It may also mean providing electrical hookups for car rechargings, hydrogen refilling stations, and other such equipment for alternative fuels.
In terms of energy creation, especially electricity, sustainable infrastructure means using methods that are not heavily reliant upon fossil fuel. This includes building infrastructure such as wind farms, nuclear power plants and even hydroelectric plants that do not rely on these resources. While these may have their own problems and critics, they are at least considered sustainable in the long term. Plants using coal and natural gas as their main sources of energy are not sustainable over many years because the consumption of those resources far outpaces the ability of those resources to replenish themselves.
In the long run, the main goal of sustainable infrastructure is to promote sustainable living amongst the entire population. One such community doing just that is Ashton Hayes, a town of approximately 1,000 people in England that aims to eventually be carbon neutral. According to the plan they have developed, they hope to return to hydroelectric power and plant 16,000 trees, among other things.