Reducing Urban Charcoal Externalities through Solar Technology: Experimental Evidence from Enterprises

Last registered on April 22, 2025

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Pre-Trial

Trial Information

General Information

Title

Reducing Urban Charcoal Externalities through Solar Technology: Experimental Evidence from Enterprises

RCT ID

AEARCTR-0015816

Initial registration date

April 16, 2025

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published

April 22, 2025, 9:54 AM EDT

First published corresponds to when the trial was first made public on the Registry after being reviewed.

Locations

Country

Tanzania, United Republic of

Region

Dar es Salaam

Primary Investigator

Name

Yonas Alem

Affiliation

University of Gothenburg

Contact Primary Investigator

Other Primary Investigator(s)

Additional Trial Information

Status

On going

Start date

2025-04-14

End date

2025-12-31

Keywords

Environment & Energy, Finance & Microfinance, Firms & Productivity

Additional Keywords

JEL code(s)

G21, H32, O13, O33, Q23, Q42, Q51

Secondary IDs

Prior work

This trial is based on or builds upon one or more prior RCTs.

Abstract

Charcoal is the key fuel used for cooking by households, enterprises, and other institutions in Africa. Charcoal consumption has serious environmental, climate, and health negative externalities. Previous experimental studies investigating biomass fuel use, including charcoal, exclusively focused on households. Understanding the biomass energy consumption of enterprises and the scope for transition to a cleaner energy source is critical because enterprises consume more than half of the biomass fuel in developing countries. In this project, we investigate the charcoal use behavior of enterprises, more importantly, restaurants and pubs, which consume substantial amounts of charcoal for cooking and boiling water. We collaborate with a reputable solar company and distribute high-cost 200-liter capacity solar water heaters (SWHs) that replace charcoal water boilers on credit with two repayment contracts (payback daily and payback weekly). We identify the impact of SWHs on charcoal consumption, CO2 emission, and enterprise profitability. We also study the credit repayment behavior of enterprises.

External Link(s)

Previous trial the current trial builds on.

Registration Citation

Citation

Alem, Yonas. 2025. "Reducing Urban Charcoal Externalities through Solar Technology: Experimental Evidence from Enterprises." AEA RCT Registry. April 22. https://doi.org/10.1257/rct.15816-1.0

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Experimental Details

Interventions

Intervention(s)

The intervention randomly provides solar water heaters to a sub-sample of the restaurants on credit under two repayment contracts (payback weekly and monthly).

Intervention (Hidden)

Intervention Start Date

2025-04-21

Intervention End Date

2025-05-31

Primary Outcomes

Primary Outcomes (end points)

The first outcome variable is restaurant uptake of solar water heaters and whether it varies by credit repayment scheme (contract). The second key outcome variable is charcoal consumption and restaurants' corresponding carbon dioxide (CO2) emissions.

Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)

The secondary outcome variable of interest is the energy cost to enterprises for water boiling, which is measured by the quantity of each fuel used for water boiling times the unit cost.

Secondary Outcomes (explanation)

Experimental Design

We randomize 210 enterprises into one of the two treatment groups and a control group. We will provide the control group with full information on the solar water heater (SWH) technology, including the different components, how it works, durability, care, and estimated cost savings from replacing charcoal water boilers with SWHs. We will offer the control group (70 restaurants) the SWHs at the market price (about USD 680) paid upfront. We will provide the first treatment group (70 restaurants) the same information as the control group regarding the SWH technology and will offer the SWHs 20\% the cost of the SWH (USD 680) upfront and the remaining 80\% including the interest in six months payable daily in about 180 small installments. We will offer the second treatment group (70 restaurants) the same information as the control group regarding the SWH technology. We will offer the SWHs 20\% of the cost of the SWH (USD 680) upfront and the remaining 80\%, including the interest payable in six months in 25 weekly payments. Ensol Tanzania Ltd, the solar dealer company we collaborate with, will use the local online cash transfer platform (M-Pesa) to collect the repayment from enterprises. We will collect panel data from the treatment and control groups before and after the interventions to maximize statistical power. The key hypotheses we aim to test are if uptake differs by the type of contract and whether uptake of the SWHs has an impact on the outcome variables of interest.

Experimental Design Details

Randomization Method

We use a Stata randomization generator.

Randomization Unit

The randomization units are restaurants.

Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters

35 clusters.

Sample size: planned number of observations

For a previous information nudge experiment, we collected baseline data from 1203 restaurants located in 130 clusters (streets) in Dar es Salaam, Tanzania. Streets are the lowest administrative unit in Tanzania. For the current trial, we used the Stata random generator and selected 210 restaurants (70 for treatment 1, 70 for treatment 2, and 70 for the control) spreading in 35 clusters.

Sample size (or number of clusters) by treatment arms

Treatment 1 = 70 enterprises, Treatment 2 = 70 enterprises, and Control = 70 enterprises. We will collect two to three rounds of data before intervention and two to three rounds after intervention, which will give 840 - 1260 observations.

Minimum detectable effect size for main outcomes (accounting for sample design and clustering)

Supporting Documents and Materials

IRB