Decreasing fossil fuel resources and global warming have forced the world to look into alternatives to the current energy supply. While wind and solar technologies are regularly talked of, biomass seems to play a less prominent role in people’s thoughts, despite the fact that the biomass share of all renewables was 80 percent in 2008.
Although wind and solar technologies seem to be more prominent, they have serious drawbacks. In particular, they are intermittent, only producing energy when the wind blows and the sun shines. RWE estimates that each wind plant has to be matched with a conventional power plant as backup. By contrast, biomass can provide base load power like nuclear and coal power stations do currently.
Biomass can be sourced from forestry and energy crops but also from agricultural and forestry residues and organic wastes from households and industries. There is a controversial discussion going on as to whether there will be enough bio energy available as it competes with food crops.
There are many reports suggesting a wide range of availability. The World Biomass Association states that biomass can supply all energy needed by 2050 while a more conservative report by the UK Energy Research Centre suggests that up to one fifth of global energy could be provided by biomass without reducing food production. The main reasons for divergent results are differing assumptions about population, diet and land use. Other important factors include the speed at which new technologies are adopted in order to improve the productivity of food and energy crop production.
Environmental impact
Biomass availability and price development arise from a complex mix. While the western world produces a surplus of food which, to a large extent, is exported to the global market with subsidies, the farmers in developing countries cannot produce enough as they lack suffi-cient resources and face distorted market prices.
Though European agriculture still receives subsidies, farmers nevertheless have to deal with very volatile market prices due to weather conditions and speculation. Energy crops can be a good alternative for farmers as they secure a more stable income. This is partly the reason biogas is popular with farmers.
The public has the impression that energy crops will have a severe impact on the envi-ronment, which mainly results from single-crop farming of corn for biogas or the cutting of virgin forest for palm oil plantations. Governments have to watch these developments and set the right economic incentives and regulatory frameworks.
In the future, farming of food and energy crops will have to meet sustainability criteria similar to the standards introduced in the forestry industry. Sustainable land use and resource competition will be the key factors for the availability of bioenergy. High conversion efficiency will be essential.
Biomass cogeneration
The many alternative uses of biomass indicate that it should be applied in cogeneration tech-niques which produce both power and heat. Greater efficiency is the Holy Grail of renewable energy. Small-scale cogeneration plants have significant advantages over large-scale, centralised combustion-based biomass power plants in terms of higher efficiency and lower fuel risk. The most common technologies of biomass cogeneration are combustion plants with boiler and steam cycles or biogas plants. Biomass combustion with a steam cycle below 10MWe is not very efficient and has high specific costs.
Biogas cogeneration is currently very successful, in many cases using corn to boost the fermentation process, but some are objecting to single-crop farming of corn. Rising corn prices also question the economic viability of the process, especially if the heat cannot be used. The energy content of the feedstock is not used efficiently and potential methane leakages have a higher impact on global warning than CO2.
Recent developments of gasification technologies promise to overcome many shortcomings, though they are yet to reach the commercial stage. Heat-only gasifiers are already commercially available, but the producer gas (synthetic gas) of a gasifier requires very low tar levels if it is used in cogeneration with a gas engine.
The benefits of gasification include higher electrical efficiency than biomass combustion with steam cycles, as well as higher feedstock efficiency than biogas. Assuming basic biomass conditioning gasification technologies have a relatively high fuel flexibility and can use low-priced solid biomass feedstocks like wood waste, solid organic waste or energy crops growing on marginal lands.
The High Temperature Agent Gasification (HTAG) concept provides low tar levels and is designed for industrial heat sinks and distributed heat networks. It is an ideal substitution for fossil heat applications, replacing natural gas or diesel. In combination with an interesting business model, it offers a very competitive investment. With new, cutting-edge gasification technologies like HTAG, heat sink owners can transform their costly heat production into actual income.
Looking ahead
It will be a mix of renewables that eventually replaces the current dependency on fossil fuels, not a single technology. Biomass is one of the most dispersed energy resources and is avail-able almost everywhere. Bioenergy will remain the most important alternative to fossil fuel. Governments need to set the right framework to balance between food and energy usage and to overcome price distortions.
The bioenergy sector is worthy of more attention from private investors to unlock its full potential. It is more complex than solar and wind power, but it also rewards investors with good double digit return on investments – higher returns than usually seen for wind and solar.
Bioenergy is a multi-billion dollar market driven by rising power prices and renewable portfolio standards. Small scale biomass cogeneration (<5MWe) has significant advantages over large-scale, centralised combustion-based biomass power plants in terms of higher efficiency and lower fuel risk. It generates attractive, safe and stable returns, which are welcomed by any investor facing the current volatile markets.
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