Bottom Up’ System - Piggyback
This is a device which is added to an existing truck or trailer to scrub the ambient air, primarily of
particulates. The motion of the vehicle is the main source of air flow, although internal fans may be used
as well at very low speeds such as during congested driving.
One embodiment is a modified roof fairing on the cab of a truck, preferably a class 8 on-highway vehicle,
inside of which is a system for filtering particulates from an ambient airflow.
For simplicity, cost, and weight considerations, this is most likely a high capacity HEPA filter. In
addition, it has a pre-filter system to remove airborne debris and larger particles, as well as precipitation
and a draining system for same.
A cross-section of the roof fairing filtration system.
The figure below shows the roof fairing filtration model closed (left) and open (right).
There are other embodiments of this general concept than the one shown.
The system includes an actuator that opens an aperture that directs air flow through the filter. In a
preferred embodiment the flow is automated and calibrated based on a control algorithm which
incorporates various inputs including those from ambient pollution and vehicle speed sensors.
In a preferred embodiment this is an addition to an existing design for an electric truck. It is designed to
interfere as little as possible with the commercial operation of the truck. For example, the aperture
remains closed during high speed travel through areas with low pollutant concentrations. It opens in areas
of high concentration at low or medium speeds. The amount of flow is calibrated to maximize particulate
capture subject to certain constraints, e.g., the effect of increased air drag.
The cost of manufacturing and maintenance is borne proximately by the fleet or commercial user. The
increased cost of operation with this device is intended to be minimal. For example the increased energy
demand due to the weight of this device, or periods of increased air drag are projected to be minimal,
below the level of resolution of most commercial operations. In particular the control system, which will
shut the aperture at times of high speed/areas with low pollutant concentration such that the roof fairing is
indistinguishable from a typical one, ensures that increased energy consumption due to increased air drag
is not significant.
The benefits of particulate reduction from mobile sources - the impact on health and climate change - are
reaped by society as a whole. The bridge to transfer one to the other is marketing. Imagine the carrier or
large retail shipper whose ad campaign is “Every order you make with us ... cleans the air!”. Increased
business volume will pay for the cost of this system.
This ability to proactively clean the air, tied to electric trucks, will help accelerate their adoption.