Biofuels would seem to be a natural renewable for a planet with a long-term history as a successful biosphere. Jon Herbert considers how human intervention might shape their future.

Trees. Since the last Ice Age gave way to the Wildwood some 10,000 years ago, timber has been a reliable native energy source for Britons. Locally grown wood is not a fossil fuel. It does not release ancient carbon to the atmosphere. In the modern power mix, bio-energy is an essential renewable.

Decisions to be taken in 2012 may help determine the future role of organic biomass — principally wood — in the UK's secure energy palette. While bioenergy plants will continue to operate on a large scale, their viability could rest on subsidy levels ministers decide to apportion. The indications are they will be more modest than for other renewable fuels.

Timber as a structural material also operates within a marketplace. Not everyone is happy with supply-demand effects that they see pushing lumber prices seriously upwards. There is concern too that growing demand for wood inevitably means further deforestation around the world, with major carbon implications. Transportation alone can add significantly to wood's carbon footprint. But that is not necessarily the end of the story for bioenergy. Innovation may see the photosynthetic energy of biomass harnessed by new technologies.

Biofuture

Bioenergy has an indispensable role in helping the UK to meet its 2020, 2030 and 2050 carbon reduction targets, according to the Department of Energy and Climate Change (DECC). It suggests biofuel accounting for up to half of the renewable energy needed to meet 2020 commitments. However, DECC acknowledges that this must be in line with biodiversity, land use and climate change policies. It also recognises the potentially competing uses of biomaterials — one global concern is marginalisation of land needed for food production.

The last official bioenergy sector study was the Government’s UK Biomass Strategy (2007). Current work, which will be reported on in Spring 2012, focuses on the availability of sustainable feedstocks up to and beyond 2020. It also looks at potential economic and carbon impacts of biomass in the energy sector. Different options for using biomass feedstocks — from electrical generation to heat and transport — are also considered in terms of parallel policy targets.

Meanwhile, the Committee on Climate Change (CCC) has looked closely at the role of bioenergy in meeting statutory carbon budgets and kindred targets in the light of land use, technical, economic and wider sustainable perspectives. It has advised the Government of resource availability, life-cycle emissions, sustainable standards and bioenergy applications across many sectors. The CCC believes developing bioenergy and Carbon Capture and Storage (CCS) technology in tandem is very important. It sees bioenergy accounting for 10% of total energy generation by mid-century, compared to 2% at present. More than 10% might begin to conflict with other environmental and social aims, it says.

The CCC makes five recommendations to government.

  1. Strong regulatory frameworks are needed to ensure emissions fall rather than rise — as could be the case with inappropriate land use — leading to tighter CO2 emission criteria for biomass power generation.

  2. CCS needs to be demonstrated as an effective technology that can be applied to biomass without delay.

  3. Government should delay raising bioenergy targets until current low supply issues are addressed. The alternative might be to risk unsustainable solutions.

  4. Offering new subsidies for large-scale biomass power plants, under the Renewable Obligation, would be costly and unsustainable. Instead, the focus should be on co-firing with coal and the conversion of existing coal plants, plus small-scale units fed by sustainable local biomass sources.

  5. Bioenergy is limited by supply and therefore should only be developed in tandem with other renewables.

Aviation is one area where biofuels could play a future role in emissions reduction. However, biofuels are only likely to play a niche role in surface transport systems. Meanwhile, old cooking oils, aerobic digestion plants utilising farm waste and wood chips from tree surgery waste are sensible smaller-scale bioenergy applications, says the CCC report.

Growing prices

Other wood users are concerned by what they regard as the distorting effects of subsidies operating in the UK since 2002. They see scant security gains because of high import levels and note that while wood burning only releases carbon stored during trees growth, nevertheless this would otherwise remain locked within living trees.

However, the competitive use of wood is forcing up prices. The Furniture Industry Research Association and Wood Panel Industries Federation are among those seeing this as a clear link jeopardising wood as a sustainable building and manufacturing material. Dedicated biomass power stations presently receive a subsidy of some £75 for every tonne of wood burned; co-firing plants between £25 and £50. UK harvested wood can cost £60 a tonne. Subsidies are designed to cover the high costs of building, or converting, stations but are seen as a disproportionate advantage to the power industry. Whether subsidy levels continue, and whether they also encourage more wood combustion, is for the Government to decide in 2012. At present, UK forests yield some 10 million tonnes of timber annually; demand by 2030 on present trends could rise to 50 or 80 million tonnes. That would mean an awful lot of trees to be planted very soon.

Yorkshire's burning

Plans by the Drax complex for two new biomass-fired plants in Yorkshire and Lincolnshire could swing on what the Government decides. In August, Energy Minister Charles Hendry announced the go-ahead for a 299MW biomass plant beside the existing 4000MW Drax power station at Selby, North Yorkshire, plus a similar capacity plant at South Killinghome, near Immingham. Each would produce enough power for 500,000 homes. The minister commented: “They will not only enhance our security of supply, but provide low-carbon electricity that reduces our carbon dioxide emissions.”

Pending a Government decision, Drax has described the investment case for its £2 billion plan as “highly challenging” and is “disappointed” that levels of subsidy so far proposed are lower than those for other renewables, such as wind.

The Government also gave the go-ahead early in the autumn for an Angelsey plant that could power 300,000 homes. After years of scrutiny, the Environment Agency Wales has issued an environmental permit. Wood pellets from local and sources imported via the port of Holyhead would be its fuel. Mr Hendry added: “We want a balanced energy platform and we want bio-mass to play a key role in this.”

Microwaving biofuel

Biofuels can come from other sources too, large amounts of waste food being one. 2012 should see a demonstration unit able to microwave at high power anything containing cellulose — including paper and card — to produce chemicals and biofuels on a domestic or industrial scale. It is estimated that a £1 million plant should be capable of microwaving some six tonnes of food waste an hour. The technology, which is being developed at the University of York, could address a world problem. African cassava production leaves 228 million tonnes of unused starch annually. Europe produces three million tonnes of coffee grounds. Farming has extensive biowaste. Brazil — where half an orange is used to make juice, leaving the rest to be microwaved — aims to put eight million tonnes of peel and pith to good use.

Rise of the green slime

Algae has long been a promising but challenging potential biofuel source which is hard to put to commercial use. The University of Bath, working with start-ups, is at the forefront of new developments that could see carefully modified strains doing more than simply functioning as biomass. The concept is to use wastewater, CO2 and other waste streams to yield biofuels as direct bi-products of digestion.

The idea of using algae or bacteria to combine light, carbon, water and nutrients in large quantities has been a grail every time oil prices have risen. The University of Swansea recognises the potential advantages of algae which theoretically can be seven times more productive than ordinary plants. US universities are also hot on the trial. Many of the problems are practical. Algae can be cultured extensively. But algae by its nature tends to block out light other than over a thin surface layer. Retrieving produced oils can also be a problem. And global algae cultivation is currently limited to circa 20,000 tonnes; millions would be needed as a commercial resource. Solving the intractable problems seems likely to pivot on engineering organisms which produce specific desirable molecules at low costs. Diesels, proteins and food oils?

Last reviewed 11 January 2012