Professor Kirk Semple, Matt Riding (LEC) and colleagues from LEC, CEH and The James Hutton Institute

Dr Ben Herbert and Lois Ricketts (Stopford Projects Ltd)

Land Conditioning Products from

Bio-energy Generation

Developing a suite of novel soil conditioners and plant fertilisers from ash and digestate waste

streams originating from biomass energy generation.

1. Project Rationale

Sustainable forms of energy generation using

biomass such as gasification and anaerobic digestion

(AD) are rapidly growing, and forecast to generate

15% of the UK's energy demand by 2020. AD alone

has the potential to deliver over 40 TWh of

renewable energy, equivalent to over 10% of the

UK's domestic gas demand. As such, waste from

energy generation, including ashes and digestate,

are produced in large volumes and are likely to grow.

The dominant disposal route for ash from

gasification plants is to ash lagoons and landfill;

whilst digestates, derived from AD, are typically

disposed of to land at no cost. However, in the face

of rising pressures on environmental resources,

rising landfill taxes and accompanying waste-

minimisation legislation, alternative options for

waste reuse are increasingly being sought.

3. The Technology

Anaerobic digestion (AD) converts organic waste

materials into biogas and digestate. Biogas, consisting

of methane (60%) and carbon dioxide (40%) can be

used to generate heat and power, or purified and

injected into the gas network. Digestate can be used

as an organic fertiliser and soil conditioner. The AD

process is entirely natural and is carried out by micro-

organisms already present in the waste streams,

which thrive in an oxygen-free environment.

Consequently, the process takes place in large, air-

tight vessels which are designed to maximise biogas

generation and recovery.

Gasification is an emerging thermal conversion

technology that is being used to generate energy from

carbonaceous materials. The process operates under

sub-stoichiometric oxygen conditions, using a

carbonaceous feedstock, to produce low energy

synthesis gas (syn gas), comprising of hydrogen,

carbon monoxide, and a process ash. This gas can

then be used as a fuel to generate electricity or as a

precursor for chemical synthesis and fuel production.

1000

10000

100000

1000000Nitrogen

Water

Soluble

Phosphor

us as P2O5

Water

Soluble

Potassium

as K2O

Calcium

Magnesiu

m

Sulphur

Ash a Ash b Ash c Ash d Ash e

0.1

1

10

100

1000

10000

100000

1000000

Aluminium

Arsenic

Boron

Cadmium

Chlorine

Copper

Iron

Manganese

Molybdenum

Nickel

Selenium

Silicon

Sodium

Zinc

7. The Vision

Widespread adoption of this

technology could result in a

sustainable substitute for

conventional chemical fertilizers, in

turn significantly reducing the

carbon footprint of the agrochemical

industry. Furthermore, utilising the

growing waste stream of biomass

by-products to promote the growth

of crops, including energy crops, will

close the production loop for

biomass to energy generation

enabling a cradle to cradle approach.

5. Micro- and Macro-Nutrients

Previous studies have demonstrated that biomass-ash and digestate can be

useful nutrient sources for crop plants in nutrient limited conditions. Although

virtually nitrogen free, ash is rich in many micro- and macro-nutrients. These are

profiled for ash from a variety of sources in the star plots (left). Contrastingly,

anaerobic digestate is a rich source of trace metals and nitrogen, as well as

relatively stable forms of C, which may improve soil structure and enhance C-

sequestration within soil. Further work profiling the nutrient content of

digestate is currently being conducted.

It is hypothesised that a combination of ash and digestate may be regarded as

comprehensive nutrient provider and soil conditioner.

Micro-nutrient Variability (mg/kg)Macro-nutrient Variability (mg/kg)

6. Partnering with

Business

The project is engaging with strategic

industry partners, and operating both

academically and commercially

throughout the energy from biomass

and agrochemical space. This enables:

• Effective understanding of the

market

• Meeting the requirements of the

end user

• Accelerate product development

• Incorporation of policy and

regulation into scientific research

2. Key Aims

The objective of this project is to radically change the way in which biomass energy

producers can support a circular economy, through utilising bio-energy waste streams to

develop soil conditioners and plant fertilisers, facilitating new ways to mesh commercial

ideas with positive environmental benefits. This will be achieved through four aims:

1) Assess the environmental impacts of applying a waste derived product to land

2) Optimize a novel soil conditioning material derived from bio-energy waste (ash and

digestate)

3) Develop a land conditioning product with a significantly reduced environmental

impact to that of conventional mineral based fertilisers.

4) Close the nutrient cycle and ensure food security

A) Technical AssessmentLiterature Datasets

Chemical Composition

Physico-Chemical Analysis

Environmental Samples

Crops Trials

Product manufacture

B) Environmental AssessmentCarbon Sequestration

Nutrient Cycling

Bioavailability

Toxicity

Biodiversity

Biogeochemistry

Carbon/Water Foot Printing

C) Health AssessmentEmissions

Exposure

Food Chain Transfer

Ecosystem Impact

Human Health

Waste TypesAnaerobic Digestate

Biomass Ash

Waste CompositionChemical Composition

Metals, Nutrients, Elemental

Bioavailability & Speciation

Physical Characterisation

Waste ArisingsMarket

Quantities

Disposal Costs

Forecasting

FormulationChemical/Physical Composition

analysis

Technology TrialsGlasshouse Performance Trials

Crop Health and Yield

Product Efficiency

Soil Condition

Performance Benchmarking

Technology Optimisation

RegulationField Trials

Product Registration

Technology ApplicationMarket

Quantities

Forecasting

PolicyRenewable Energy Directive

Landfill Directive

Government Incentives

Waste Incineration Directive

Resource Recovery

RegulationResource Recovery from waste

Waste Re-use

Waste to Product

Waste to Land

Public PerceptionConsumers

Supermarkets

Supply Chains

Attitude to Waste

“Nimbyism”

Soil ConditionersFormulations/Compositions

Performance

Cost

ApplicationsCrop Type

Soil Type

Application Period

RegulationProduct Registration

Efficiency Trials

MarketMarket Size

Value

Forecasting

4. Project Development

424400

4656000

0.00E+00

5.00E+05

1.00E+06

1.50E+06

2.00E+06

2.50E+06

3.00E+06

3.50E+06

4.00E+06

4.50E+06

5.00E+06

Thermal Treatment Anaerobic Digestion

By-product Source

To

nn

es

ye

ar

-1

20

112

0

20

40

60

80

100

120

Thermal Treatment Anaerobic Digestion

Nu

mb

er

of

Pla

nts

Plant Type

A Whole Systems Approach

Legal, Environmental and Social Considerations

Scoping Research DevelopmentNumber Bio-energy

Plants

Quantity of Waste

Generated by Plant Type

Macro- and micro-nutrient content of ash derived from bioenergy plants representative of a number of different feedstocks

and plant types.

http://www.lec.lancs.ac.uk/news_and_events/events