Kazakhstan is a large steppe country located in Central Asia. It is surrounded by Turkmenistan, Uzbekistan, and Kyrgyzstan to the south, Russia to the north, China to the east, and is bounded to the west by the Caspian Sea. The country has a total land area of 2.7 million km2, sub-divided into fourteen administrative provinces (Fig. 1a), each governed from a local centre, usually the largest local city, which is called the capital of that province. Generally, the climate of Kazakhstan is extreme continental with average temperature between -4 and -19 ∘C in January and between +19 and +26 ∘C in July. The country is almost entirely covered by steppe and desert with brown and grey-brown soils; the northern area of Kazakhstan is the wettest region, where precipitation exceeds 300 mm yr-1 (Fig. 1b), mainly because of afternoon thunderstorms that occur in summer, while in the centre and south, precipitation is around 150–200 mm yr-1 (KIG, 2013). According to Kazakhstan's Agency of Statistics, the country has an estimated population of around 17.8 million (KAS, 2016) and 60 % of people live in cities (Nyussupova and Kalimurzina, 2016). The energy sector plays a major role in Kazakhstan's economic development. The country has abundant reserves of fossil fuel (oil, gas and coal) and proven gas reserves estimated at about 3.8 trillion m3 (EIA, 2017). Natural gas and clean energy technologies have the potential to contribute to reducing the country's carbon footprint (Kerimray et al., 2018); there are plans to build additional gas infrastructure that will bring natural gas to Kazakhstan's capital of Astana, and large cities in the North and Central Kazakhstan (MoE, 2018). Gas grid connectivity is expected to reach 56 % of the population by 2030, compared to 47.3 % currently (MoE, 2018). The potential oil resources in Kazakhstan are estimated to be over 30 billion barrels and Kazakhstan is a strongly export dominated economy with between 75 %–80 % of its total oil production exported overseas. In 2016, oil production was around 79.4 Mt against a consumption of 14.6 (EIA, 2017). Kazakhstan has also significant coal reserves, especially in central part of Kazakhstan. Its total recoverable coal reserves were estimated in 2015 at around 176.7 million short tons (EIA, 2017). Despite the abundance of oil and gas, the country's power generation has been dominated by coal. By the end of 2016, coal-fired thermal power in Kazakhstan comprised 75 % (15 GW) of the total installed capacity and contributed 80 % (82.4 TWh) of total generated electrical energy, mainly concentrated close to the coal fields in the North of Kazakhstan (Fig. 1c). The North and Central regions of Karaganda, Pavlodar, Akmola, Kostanay, Aktobe, East Kazakhstani provinces have a 220–500–1150 kV electric grid that is connected to Russia's electricity system (Fig. 1d) and these provinces have higher electricity consumption than in the West and South (Fig. 1e) (KEGOC, 2016). Coal is expected to play a dominant role in national energy balance at least for the next 30–40 years (Kazenergy, 2017). The domination of coal in Kazakhstan's current energy balance coupled with its aging plant and unequal spatial distribution networks (including electricity production) contributes both to regional energy price inequalities (Assembayeva et al., 2018) and to ongoing serious environmental damage (Kerimray et al., 2017). Coal power stations are responsible for almost 80 % of the country's carbon emissions (ICSD, 2016). The quality of Kazakhstani coal is relatively poor, with a high ash content of between 50 % to 65 % (EIA, 2017). Given current and projected future coal use in Kazakhstan, and the need to cut emissions, biomass co-firing in coal power stations is regarded as a promising option which could enable Kazakhstan to cut its carbon emissions and provide an improved sustainable energy supply.

Currently, there are three co-firing technologies widely used in power plants: direct co-firing, indirect co-firing, and parallel co-firing. In direct co-firing, biomass is directly fed into the furnace along with base fossil fuel (e.g. coal). Indirect co-firing installs a separate gasifier to convert the solid biomass into a fuel gas (syngas). Parallel co-firing involves the installation of a completely separate external biomass-fired boiler in order to produce steam used to generate electricity in the coal-fired power plant. Biomass co-firing does not require significant capital investment and has the advantage of being able to use existing fossil fuel power plants infrastructure (Roni et al., 2017). Biomass co-firing can replace between 20 %–50 % of coal and reduces carbon dioxide emission from the power plant; the amount of other pollutants released will depend on the characteristics of the biomass feedstock (Lempp, 2013).

Kazakhstan has various biomass resources including forest wood and agricultural residues. While the spatial distribution and potential of solar and wind energy has been previously demonstrated (UNDP, 2015, 2018; Terehovics et al., 2017; Ahmad et al., 2017) to date there has not been any analysis of bioenergy feedstocks for potential use in energy generation in Kazakhstan. Here we present the available biomass resources (crop residues, the production of livestock residues and forest residues) and then evaluate for the first time the total amount and the spatial distribution of the crop residue availability for energy generation. This type of assessment is needed by policy makers and local governments in their efforts to establish medium- and long-term planning for the development of biomass and biogas resources, and for enterprises and planners to arrange for the development and implementation of projects related to biomass resources.

To promote the development of renewable energy in Kazakhstan, the government issued the National Green 2050 Economy Concept in 2013 (no. 577 of 30 May 2013), followed by the Law on Green Economy in 2016 (no. 506-V of 28 April 2016) and the Renewable Energy Action Plan for 2012–2030 (Directive no. 068 of 24 February 2017). Kazakhstan has set the target of raising the share of renewable resources in electricity production from 3 % by 2020 to 50 % by 2050 (Karatayev and Clarke, 2016). These targets and government strategies encourage the uptake and commercialisation of biogas, biomass-derived liquid fuels and biomass generated electricity sectors (Karatayev et al., 2017). The National Parliament has approved a Law on the Regulation of Production of Energy from Biomass Resources no. 351-IV and National Tariffs for Energy Produced from Biomass Resources (Directive no. 645 of 12 June 2014). In 2016, the Ministry of Industry and New Technologies proposed four projects of biofuel production in North and South Kazakhstan (Fig. 3c and d). However, the development of a modern bioenergy sector in the country is still limited due to a number of specific barriers that resource-rich countries currently face (Karatayev et al., 2016). The current availability of fossil fuels coupled with insufficient political will have hindered the development of the renewable energy sector in Kazakhstan (Karatayev et al., 2016). Artificially low electricity prices, subsidised up to 60 % by the government, continues to be one of the main drivers of energy policy in Kazakhstan. In order to enable development of the bioenergy industry in Kazakhstan we recommend:

Biomass co-firing technologies should be included in national energy targets, programmes and legislation especially given that existing power plants can be easily adapted. The European Union countries adopted the 2020 Energy and Climate Directive (Directive 2009/29/EC) setting three key targets including a 20 % cut in greenhouse gas emissions (from 1990 levels), 20 % of EU energy from renewables and 20 % improvement in energy efficiency. The Directive on Renewable Energy (2001/77/EC) provides the framework for electricity production from biomass and the Biomass Action Plan (2005/628/EC) states that electricity can be generated and co-fired from all types of biomass, by mixing it with coal or natural gas, or to run freestanding power stations. At a national level, the UK adopted the National Bioenergy Strategy that aims to promote generation of heat and electricity from biomass resources. Additionally, the UK developed the Energy Crop Scheme that provide farmers with grants for establishing energy crops such as short rotation coppice and miscanthus. Currently, all major coal-fired power plants in UK have adopted biomass co-firing. On average, these plants fire 5 %–10 % biomass by energy basis. Most plants began their co-firing experience with co-milling trials and then moved on to establish direct injection systems for commercial production. A variety of feedstock has been utilized in UK's coal combusting plants, including: agriculture residues, energy crops and forestry residues. This provides a good model for Kazakhstan to emulate.

Here we have demonstrated how ArcGIS combined with theoretical energy potential offers decision-makers information on the availability and type of biomass options for Kazakhstan. Biomass co-firing is an attractive option for reducing carbon emissions as it can use existing power plant infrastructure. In this paper, we have identified the main residues available in Kazakhstan for bioenergy production as well as their geographical distribution. The bioenergy potential is estimated about 485.36 MJ (or 16.582 Mt of coal equivalent), which account for about 30 % of total current energy consumption of the country. Wheat residues constitute the major part of Kazakhstan's bioenergy potential, accounting for 44 % of the total bioenergy potential. The results also reveal an imbalance in the spatial distribution of bioenergy resources, driven by climate and topography. The northern and southern provinces of Kazakhstan have the highest bioenergy potential from wheat residues, while the dryland central provinces have the least potential. Aridity, salinization and land degradation ensures that the western provinces are inappropriate for bioenergy production from biomass. The top three provinces with the highest crop biomass energy resources are Akmola, Kostanay, and North Kazakhstani provinces, located in the north of Kazakhstan. Considering the fact that main country's coal-fired power plants are located close to the biomass source regions in the Northern part of Kazakhstan, it is feasible to apply biomass co-firing technologies in this region of Kazakhstan. To ensure the viability of such an initiative some additional work is now required to estimate the: (i) technical energy potential from livestock and forest residues; (ii) logistics of the resource supply chain including geographical accessibility, transportation cost and certain radius of the thermal plants; (iii) carbon emission reduction potential under different scenarios on development of bioenergy and policy actions in Kazakhstan; (iv) biomass energy subsidies and costs.