Project Implementation

K. The Work plan

The project will be implemented in two phases. Phase I (Agronomy, years 1 & 2) centres on the selection of appropriate sweet sorghum varieties, planting and management regimes to ensure the appropriate quality and quantity of biomass will be available for ethanol heat and electricity production for Phase II. Phase II (demonstration and dissemination) will be carried out in year 3, after the mid-term assessment conducted at the end of year 2 . In Phase II sufficient sweet sorghum biomass (300 ha) will be produced for crushing and conversion to ethanol, heat and electricity utilising the Triangle Ltd's mill and equipment. Phase II will only be implemented after the successful completion of phase I, as assessed by the mid-term review. The systems analysis model will be developed in conjunction with both Phase I and II.

Phase One (1st and 2nd years)

Agronomic Trials

Agronomic trials at intermediate scales (10 ha at Triangle/Chiredzi, 3 ha at Harare Research Station) will be conducted to verify critical scale-up yield data.

1st YEAR

Trials will be carried out at the Chiredzi Lowveld Research Station, situated 20 km from the Triangle sugar mill, and in the heart of the local sugar estates. The research station will provide the correct environment to develop the monitoring methodology necessary to measure the water, nitrogen, sulphur, carbon and radiation balances in order to carry out a proper environmental audit. The station will also provide the required conditions to carry out the detailed growth analysis needed to optimise the integration of sweet sorghum with sugarcane.

Triangle / Chiredzi:

The 10ha trial will be subdivided into two 5 ha sub-trials of random block design. This will allow a short season variety (3 month growth season) and long season variety (4 to 5 month growth season variety) to be monitored under simulated commercial growth conditions. The data gained from these trials will allow precise agronomic scheduling of the 300 ha planting to be carried out the following year which will produce the sorghum feedstock for crushing (approx. 15 000 t) and ethanol production. In this way the initial trial will allow mature sorghum to be produced at a rate which will not exceed the mill/crushing capacity and which also has optimum sugar and fibre levels. In conjunction with the productivity data gained from this trial, crop growth parameters will be continuously monitored in order to quantify the resource requirements for optimum growth and to provide a basic environmental impact assessment. A number of promising varieties- high sugar, fibre and total biomass, will be assessed, as economic viability is strongly correlated with these biomass quality factors.


A second smaller (3ha) trial will also be planted outside Harare. This trial will provide an experimental control under different climatic and soil conditions. The validation of the yield prediction methodology is essential for robust and accurate predictions of sorghum growth under different climatic conditions, both nationally and internationally. This trial will be located at the SIRDC agronomic research station north of Harare. The growth of sweet sorghum is not well understood under the prevailing conditions of the Highveld where Harare is situated, which has a colder dry season, but higher mean rainfall. This region is the primary agricultural region of Zimbabwe and representative of high elevation (highland) agricultural regions in Southern Africa.

2nd YEAR

The work program will closely follow that of the first year. However, the southern Zimbabwean trial will be planted on the sugar estates utilising fallow land recently removed from sugarcane production. Thus, the expertise and knowledge gained during the first trials can be applied on the fallow sugarcane land, in particular, testing of varieties with the best characteristics, including drought and disease tolerance. In order to maintain viability, where hybrid varieties are selected, it will be necessary to re-cross from the primary parent lines. A further important factor to test is the effect on productivity of utilising residual nitrogen in the sugarcane fields, and thus, possibly removing the need to add fertilisers to the sorghum crop. The nitrogen dynamics data is also necessary to obtain nitrogen fluxes in order to estimate the potential impacts, positive and negative, on the environment. {Gosse et al. 1992}

This intermediary step between agronomic trials and the full 300 ha trial is necessary, in order to adapt the small scale trial methodology to the soil and management conditions found in fallow sugarcane land. It will also allow the bulking up of seeds of the most promising varieties, which is essential for the full scale trial (300 ha). The output from the small scale trial will be run through the sugarcane laboratories and testing procedures of Triangle Ltd to check the suitability of the feedstocks for the mill.

Data Gathering and analysis

This activity will occur in parallel with the 1st and 2nd year trials. It will be directed at ensuring that the sweet sorghum growth characteristics allow sufficient production of biomass and that the biomass is of sufficient quality to minimise the risks outlined in section M. It will enable the construction of a good quality crop water balance to provide valid predictions of economic returns from any future proposed plans for full scale implementation. Other important factors which will be monitored include, sugar, fibre and moisture fractions, nutrient and energy balances as well as the duration of high sugar levels in the standing crop. The duration of sugar levels is important for integrating sorghum with sugarcane as well as for logistical analysis for harvesting and conversion rates. This data gathering activity is designed to provide the data requirements of the Systems Analysis/Decision Support system component of the work programme.

Integration and Systems Analysis

A systems analysis modelling approach is central to assessing the replicability of complex bioenergy systems at separate sites. Factors such as soils, climate, technologies and plant size are critical to successful economics and are highly variable. The inter-relationship between these factors are mathematically described in the AIP allowing rapid assessments of alternative bioenergy production sites. These issues are discussed more fully in section G and Attachment 6.

Key agronomic factors important in the development of a viable sorghum energy system will be analysed in conjunction with the data gathering activity of Phase 1. Potential impacts of variability in specific parameters will be assessed, for example, sensitivity analysis on the effect of fibre percentage of sorghum stems will be carried out. The model development has been carried out in Visual Basic, in order to provide a user friendly Windows based interface.

Model development and testing will be continued in Phase 2.

Phase Two (3rd year)

Phase two will only be carried out if Phase one is successfully completed. The decision to implement Phase two will be made as part of the mid-term review process.

3rd YEAR


300 ha of fallow land to be planted with first short then long season varieties in order to optimise biomass quality at crushing. Data from the 1st and 2nd year trials will provide a precise planting scheduling. Sweet sorghum biomass produced from these large scale trials will then be fed into the 110" roller mill for crushing and juice extraction (see data sheet). A separate juice feeding pipe to the fermentation plant will be constructed from the clarifying plant. This is necessary as the sorghum juice does not go through the sugar extraction (vacuum pan) process, and so can be fed directly to the fermentation plan after sterilisation. Full scale batch fermentation will be carried out followed by distillation. If sufficient juice is available, it will also be blended with sugarcane molasses in order to test the feasibility of this process. Tests carried out earlier by Triangle's fermentation plant laboratories have shown that sweet sorghum juice is compatible with the batch fermentation process carried out at Triangle with fermentability equivalent to B-molasses.

The sorghum bagasse will be sent to the moving grate furnaces and combusted in order to raise process steam. If sufficient steam is available, it will also be sent to one of the six turbo generators in order to test electricity generation. All stages will be carefully monitored.

{Internal Triangle report; see also Scurlock et al. 1991, for a full description of ethanol production at Triangle Ltd.}

Integration and Systems Analysis including Data Analysis and Optimisation.

Building on the work carried out in phase I, agronomic variables will be combined with the agro-industrial sectors in order to allow modelling and systems analysis of the entire process chain from crop growth through to final energy production. A five year weather data set from the Chiredzi research station will be used to carry out sensitivity analysis to climatic factors and economics. By the end of phase II, the AIP will provide a reliable model of the sorghum energy chain based on Triangle Ltd., accessible through a user-friendly Windows-based interface.


The project outputs will be summarised in a final project report which will be printed and freely disseminated.

Project reporting will be carried out according to CFC guidelines.

A Technical exchange programme with the sugar industries of Kenya, Malawi, Mozambique, Tanzania and Zambia will allow regular visits to the project to be made and training on the data gathering and modelling aspects of the project will be provided.

A one week workshop will be carried out after the successful demonstration of ethanol, heat and electricity production from sweet sorghum. The workshop will provide practical, hands-on, experience, addressing agronomy, integration, logistics and technology, utilising the systems analysis model (AIP) as a decision support system and a good technical background to the production of energy from sorghum. Technicians / agronomists from Africa, Asia, and Latin America will be invited to participate on a full cost basis to ensure that all regions are well represented.

The Systems Analysis Model (PC based) will be disseminated with the final report.


On successful demonstration and completion of the project, Triangle Ltd remain committed to the continued utilisation of sweet sorghum for ethanol production as long as market conditions remain favourable for normal profit. Continued improvements in breeding and quality of the sorghum will result in significant decreases in production costs. Furthermore, modern conversion technologies currently under development promise substantial improvements in the efficiency of energy production and utilisation of by-products with further reductions in costs.



1998 1999
























Agronomic Trials & Biomass Production Triangle Year 1 Trial 2nd Year Trials 3rd Year Trials

Year 1 Trial

Year 2 Trials
Data Gathering


Integrational & resource requirements

Production and Period of Industrial Utilisation

Data Analysis & Optimisation Harvesting & Transport Test To Mill
Juice Extraction





For Fermentation


CHP & Ethanol

Integration & Systems Analysis Data Input

Basic Agronomic


(Sorghum & Sugarcane)

Industrial processing and conversion


Development of Industrial conversion modules

Dissemination Workshop

Planning & Implementation




3rd 4th 5th & Final
Project Management 1st 12 month 


Mid-term Review 2nd 12 month 




Phase I
Phase II

L. Project inputs

Project inputs are presented according to major expenditure types used in Section N. However, inputs are also related to specific project activities within each expenditure type.

PERSONNEL: SIRDC- Researcher at Hatfield Centre, Harare, (12 months for 3 years) @ $ 1 000 per month; salary costs for data analysis and evaluation. The researcher will be in overall scientific control of the 1st and 2nd year trials, and will act as advisor to 3rd year trial.

Agronomist (based at Chiredzi Research Station, Lowveld), 6 months per year @ $370 per month. The agronomist will oversee the agronomic trials and seed bulking.

KCL- Analyst/modeller 1st and 2nd year (6 months per year) + 3rd year 8 months to include workshop preparation- salary costs for systems analysis, modelling and programming.


KCL- 2 trips (2 months duration each), ticket ($1200) + subsistence and accommodation ($ 65 per day for 60 days per trip) for data gathering and monitoring of trials.

SB (ISO)- 3 trips (1 x 8 days + 2 x 2 weeks to PEA), for project supervision ticket ($1200) + subsistence and accommodation ($ 65 per day).

CONTRACTS & SERVICES: Required for sweet sorghum production trials and analysis.

See work programme.

SIRDC- Will carry out the first and second year trials at the Lowveld Research Station and at the SIRDC Research Station, Harare. Will employ contract labour to plant and maintain the trials and carry out daily monitoring. This budget includes costs for labour, irrigation water, electricity, fertilizers, land preparation, weeding and pest control.

A vehicle will also be hired by the SIRDC researcher in order to allow flexible travelling between the Lowveld Research Station and the SIRDC research station in Harare. A second pick-up type vehicle will be necessary during the last two months of the 1st and 2nd year trials to ferry the sampled biomass between the field and the laboratory. Vehicles will be rented at government rental rates.

Triangle Ltd- In conjunction with SIRDC, Triangle Ltd. will carry out a 300ha agronomic trial of sweet sorghum on fallow sugarcane land. In addition, Triangle will carry out harvesting, transportation, crushing, fermentation and combustion of sweet sorghum storks and bagasse at the Triangle sugar mill. Modifications to the mill facilities will also be required in order to re-route the extracted sorghum juice through a clarification and concentration step directly to the batch fermenters or storage tanks, requiring extra pipework and pumps. These costs will also be met by Triangle Ltd.


The equipment is essential for the monitoring of crop growth and water efficiency parameters and is unavailable for rental in Zimbabwe. It will be continuously used during the 1st, 2nd and 3rd year trials. Water management is a key factor to optimising sorghum growth. Data derived on water, growth and sugar status will quantify resource use and therefore economic agronomic parameters. Water use will be analysed through the use of plant and soil water monitoring equipment. Plant water status and dynamics will be measured using a leaf water potential metre and a field porometer. Soil water monitoring will be done through a combination of neutron probes and classical bulk density analysis. A drying oven is essential for both the soil and plant moisture analysis. A dedicated oven will then be required at the Lowveld research site to ensure oven space is available during monitoring. The three computers (including printers and software) will all be sited in Zimbabwe: i) at the Lowveld Research station (site of year 1 and 2 trials, ii) SIRDC research centre, Harare; site of year 1 and 2 trials, and iii) Triangle Ltd, year 2 and 3. They are required for field data compilation and analysis and for logistical analysis using the AIP model.


Workshop costs: Participants: - 30

Southern Africa - 20

Other Africa - 6

Latin America - 2

Asia - 2

MANAGEMENT: The Supervisory body (ISO) will visit the project in Zimbabwe for two one week periods. The first visit will be to participate in the mid-term review, while the second visit will be to participate in the final assessment of the project.


SIRDC will be responsible for day to day management of the project.

M. Risk

Whilst there are no critical risks foreseen, potential risks affecting economic returns (as outlined in section H) and environmental impacts are outline below. As seen from table 2 (section H), a financial loss would result in the unlikely and simultaneous event of drought (therefore requiring irrigation), use of a low water use efficient variety, and low overall ethanol. However, assuming that the first and second year trials are successful, this will clearly warrant the continuation of the project into the third year.

Uncertainties relate to:

Crop failure could occur due to weeds, diseases, pests and environmental variables such as unexpected low temperatures at planting. The potential economic impact of drought is assessed in section H by analysing the effect of any irrigation costs required to maintain a yield of 50 t/ha. We address this risk by carrying out detailed research into these variables in the small agronomic trials held in years 1 and 2.

Careful logistical planning will ensure rapid transport and conversion after harvesting. The potential inputs of sweet sorghum biomass are well below the specified milling capacity and hence this area is not foreseen as a bottleneck in energy production.

Little risk is foreseen, although technical parameters concerning "pithiness" of sorghum bagasse versus sugarcane bagasse will be addressed. Two types of industrial juice extraction technologies (crushing and/or diffusion) will be assessed for extraction and energy efficiencies in this project, further minimising the risk of failure at this stage.

Laboratory tests at Triangle have shown that the extracted sorghum juice is compatible with the Triangle batch fermentation process, which is a robust fermentation technology which has now been operating for more than 10 years.

Insufficient yields of fibre will result in the need to burn coal to provide sufficient energy for crushing, concentration and distillation; however, this appears unlikely.

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