As debate over building a new prison in Philadelphia continues to draw controversy, the city on Wednesday announced it had received a grant to research ways to shrink its prison population.

Philadelphia is one of 20 municipalities that will receive $150,000 from the MacArthur Foundation to study reducing its number of inmates. In 2016, up to 10 of the cities will be selected for a follow-up round of funding to implement the plans - up to $4 million over two years.

"Right now we're not quite sure where the bottlenecks are in the system, or if there are any," said Prison Commissioner Lou Giorla. "We want to look at our data and determine if there are any ways we can create efficiencies."

Prison overcrowding has long been a problem in Philadelphia, leading to numerous lawsuits against the city.

The city's prison system - which comprises six facilities in a complex along the Delaware River in the Northeast and a handful of satellite sites - currently houses about 8,000 inmates. About 75 percent of them are being held pretrial, according to Giorla. The numbers are down from a high of about 10,000 inmates but still more than the system was designed for.

At the House of Correction - the 140-year-old facility the city has considered replacing - the population is about 275 over the 1,250 maximum, meaning cells meant for two inmates have to hold three.

A bill in City Council would allow the city to purchase a property adjacent to the House of Correction that officials have said would be ideal for a new prison in the future.

Advocates have questioned the move. And Jim Kenney, who won the Democratic mayoral primary last week and is all but guaranteed to be the next mayor, has said he would not support a new prison.

City officials have said the study will focus on alternatives to incarceration for low-level offenders and increasing opportunities for those leaving prison.

"Some people just say you're going to let dangerous people out of jail. That's not the case," Giorla said. "We want to make sure the pretrial length of stay is not excessive, the adjudication process is fair and efficient, and individuals get found guilty or acquitted or move on to the next stage of life as soon as possible."