East Donegal planners continued discussion Thursday on a proposed ordinance regulating alternative energy systems in the township.

The board — thinned by summer vacations — lacked enough members for a quorum and took no action on any items discussed at the meeting.

It also gave no indication of when it would have a draft ordinance ready for public comment, or when it would send a proposal to the supervisors.

Township Manager Jeffrey Butler said the discussion was part of an ongoing agenda aimed at adopting regulations for solar panels, windmills, hydronic heaters and manure digesters, all of which are designed to produce energy for various uses.

Butler said the popularity of alternative energy systems — and a lack of any township regulations addressing them — prompted concerns from township officials.

The board discussed solar energy systems last month. Thursday's discussion focused primarily on wind energy.

Butler said the proposed ordinance splits alternative energy systems, including windmills, into two categories — accessory use and primary use.

He said an accessory use covers on-lot systems that produce energy specifically for a structure on that lot.

The accessory use of alternative energy systems would be permitted by right in residential and agricultural zoning districts, however, there would be varying restrictions placed on the systems.

For example, Butler said, residential windmills would have to meet setback, or property-line requirements and their maximum heights would be regulated based on lot size.

Turbine noise also would be regulated under the proposed ordinance, as would the distance of rotating blades to the ground.

Butler said some residential windmills can easily tower over trees and houses.

"They can be sizable," he said.

Primary-use windmills include commercial units capable of producing enough energy to allow electricity to leave the site to be used at other facilities or to be sold on the energy market.

Butler said these types of units compare to the turbines installed recently along the Susquehanna River in Manor Township.

Planner Thomas Johnstin asked if any windmills would require approval from the Federal Aviation Administration because of the presence of the Maytown Airport in the township.

Butler said the FAA becomes involved when tall structures directly impact airport operations.

He said the township's current height ordinances are more stringent than the FAA requirements.

The maximum building height allowed in East Donegal Township is 40-45 feet, depending on the zoning area.

Township resident Jesse Wagner said any ordinance the township adopts should give special attention to windmills with unique designs.

One nontraditional design Wagner cited was a spiral staircase-shaped windmill on a property along Pinkerton Road.

The board also had a brief discussion about hydronic heating units and manure digesters.

Butler said hydronic heaters "have the most impact" of any alternative energy system.

Hydronic heaters, which can cost more than $10,000, heat homes using underground water pipes connected to a shed-like furnace that burns wood, coal or other combustible material.

Planner Cynthia LaBuda said that while the township would not limit the types of units permitted for use in the township, steps would be taken to know exactly what types of units are in use by requiring a zoning permit for the heaters.

Supervisor Dennis Drager said a hydronic heater in use on a farm near him is far enough away that all he occasionally smells is a hint of smoke similar to a chimney.

However, he said, "People will burn anything in those from household trash to a dead dog or cat." Drager said if someone burns a tire in the furnace, "you will know it."

Butler said those are the reasons such systems would face additional scrutiny in a residential neighborhood.

He said hydronic heaters, which need to be fed with wood or other approved combustibles on a daily basis, already meet tough state and federal regulations and would also face stringent setback requirements under the proposed ordinance.

The last energy system discussed by the planners — manure digesters — only relates to agricultural zoned properties. But the board said industrial zones could be included if the energy produced from the digesters had a direct impact on commercial industrial applications.

Butler said manure digesters, which break down farm manure waste into methane for burning, are also regulated by tough state and federal regulations.

The township's proposed ordinance would keep digesters 200 feet from any property line and 300 feet from any residential property. It also would address noise, odor and vibrations.

Manure digesters would require a special exception from the zoning hearing board, Butler said.

Because digester operations would require transport of manure to and from a site, Butler said the township's current generic ordinance — which only covers numbers of trips — would need to be upgraded to make sure that township roads would be able to handle any increases in heavy truck traffic.